Have you ever wanted to build a tandoor oven from scratch? Likely not... but still, stay with me and I'll show you how I built one from the earth itself - in the form of raw clay. I'll dive into the process, including designing, sketching, building, assembling, and using, and maybe you'll learn something along the way!
Hopefully this article can serve as a comprehensive guide for all those looking for info on how to design and build a good tandoor from the bare bones, as I feel the info available online is lacking. Even if you choose not to go through the pottery aspect of it, check my tips at the end for how to use a tandoor.
What is a tandoor anyways? Traditionally the word is used to refer to a cylindrical clay oven that has been used by civilizations for thousands of years. Charcoal burns at the bottom, and the radiant heat rising from it cooks meat or vegetables threaded on steel skewers placed inside the cooking chamber. Fat and marinade dripping from the meat falls into the belly of the beast, causing a smoking effect that gives a delicious, unique flavor to the food that cannot be achieved by baking in a regular oven. Bread dough can also be slapped directly onto the hot clay walls, where it puffs and cooks almost instantly to make the delectable and well known Naan bread. It is thanks to the tandoor that we can enjoy tandoori chicken — chicken marinated in yogurt and an eclectic mix of spices — a well loved classic of Indian cuisine.
One day while biting into a flavorful chunk of chicken at the local Indian buffet I had the thought: Hey, I want a tandoor so I can make this at home! And I, always looking for ways to avoid spending more money than necessary (and an unquenchable thirst for challenges), immediately thought: I should build one!
And so, a month later, here we are.
Be warned! This is a VERY LONG article. But after all, it was a LONG process. Read just what is relevant to you.
So then, let's get started.
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Step 1: Caveats for Those Who Actually Attempt This!!
Look, you can choose to go the easy route and make a similar tandoor with flowerpots and found objects. They work too, and I took inspiration from them. In fact, there are a few here on Instructables which I recommend, just search up "DIY tandoor".
However, I chose to take the idea to the next level and design and build all the parts by hand, starting with the most basic, fundamental ingredient: clay! The final result is more visually pleasing, satisfying, rewarding, long lasting, and I learned so much in the process, gaining skills I'll be able to apply later on in other projects.
It was the very last project I made in high school, and I'm glad to say I went out with a bang!
If you also want to make your own tandoor from scratch, understand that you will need access to a pottery wheel, kilns, basic tools, and must have at least a few years of experience making pottery. This is NOT an easy project and is not recommended for those just getting into ceramics. I used the studio in my school, which Ms. Amie Larson graciously let me abuse. If you're reading this, thank you Auntie Amie!
As for inputs, expect to spend several dozen hours on this and $200 in supplies (which is actually quite modest for a tandoor).
Having said that, let's move forward :D
Step 2: Materials
This project should cost around $200, which is quite modest for a home tandoor, which retails for several hundreds of US dollars. You will need:
For the Yumungous (Extra Large) Bat:
- 2' x 2' x 3/4" Plywood
- Water resistant finish (such as Minwax's Helmsman Spar Urethane)
For the Tandoor:
- at least 200 lbs (four boxes) of Raku / Heavily grogged clay (see note *)
- Underglaze of choice, I chose to make an indigo color by mixing royal blue and bright red.
- Vermiculite (one 4 cubic feet bag)
For the base:
- 4 single cinder blocks
- 4 12"x 12" brick pavers
- Extra long steel skewers (see note **)
- Bread hook and paddle, used to peel naan off the walls
- Naan Pillow or gadhi, used to stick naan on the walls
- I bought one that was too big to fit in the opening and ended up making a smaller one out of a kitchen towel which worked just as well if not better
- Good charcoal and brown paper bags or newspaper for kindling
- Tarp to protect against rain
- Some food to cook in it!
* Raku clay is a type of clay that is heavily grogged, which helps it withstand heat shock better. It is normally used in a process (called raku firing) where it is taken straight out of a hot kiln and dunked into a trashcan full of sawdust, occasionally sprayed with water too. I figured that if it can survive such an intense shock, it should hold up fine through a slow heat-up with coals. Spoiler alert: turns out, this is true!
** Regular skewers will not suffice for this, because the skewers are so short they will just fall in. I purchased eight 39" skewers, the hook and paddle, and a naan pillow for $100 on this website:
Step 3: Tools
Once again: you will need access to a pottery studio and kilns. If you choose to make the XL bat, you'll also need woodworking tools. At the bare minimum, you will need access to:
For the Extra Large Bat:
- Band saw
- Jig saw
- Painter's pyramids or a stand made of scrap wood and nails (will need metal snips for that, you'll see later on)
For the Tandoor:
- Pottery wheel with removable splash pan (it will get in the way most of the time)
- Several large plastic bats ( >12" in diameter)
- Throwing tools such as: Bucket, Wire cutter, wooden tools, needle tool, plastic, metal, and wooden ribs or kidneys, sponges, trimming tools
- Long rulers, meterstick
- Clay extruder (you can make the coils by hand but it's less precise)
- Clay slab roller (you can roll the sheets with a rolling pin but it's less precise)
- Kiln. The kiln I used was 29" in diameter and more than 20" tall. It was a very tight fit.*
- Helpers!! The large pot definitely needed two people to lift, and it took a total of six people to maneuver it into the kiln (two to hold the lid, four to transport the pot)
For the set up:
- Garden shovel
* Alas, I am not blessed with access to an absolute unit walk-in kiln!
Step 4: Design
Most of the DIY designs I had seen involved an inner pot, the main cooking chamber; an outer pot (some used a steel drum or large flowerpot); and insulation in between to keep the inner chamber hot for longer and make it more fuel efficient. Ultimately, I took inspiration from many designs I found, but I also came up with several points of improvement.
After a lot of sketching, I settled on this design for several reasons:
- The inner pot is built in two parts, which, not only is easier to make, but it also creates a ledge inside for skewers to rest so that they do not jab directly into the coals.
- The charcoal chamber and bottom of the big pot have several holes in them to allow oxygen to flow to the coals, an essential for proper combustion. Additionally, there is a 2" lip on the bottom of the charcoal chamber, which should once again lift the coals up, giving them more access to airflow.
- The unusual "donut lid" covering the section between the pots is actually very important - it prevents the lightweight vermiculite insulation from flying away in the wind or getting foreign material or water into them, ruining them.
Step 5: Wheel Throwing Basics
Again, to even consider trying to do this, you'll need some experience making pottery on a wheel. Here, I'll briefly go over the basics of the process for those who are interested.
- A chunk of clay is weighed out and wedged. In this kneading process, the air bubbles are removed from the clay.
- I prefer to throw pottery on a bat, a round, flat disk of plastic that attaches to the wheel head. First, you slam down the clay upon the center of the bat. Then, you use your finger to form a seal between the clay and the bat. Then, the clay is wet and pushed firmly down to ensure a good seal.
- In this next process, called centering, the moistened clay is forced upwards, called coning up, then pushed down 1 to 3 times until the clay is almost perfectly rotationally symmetric. This step is often overlooked but is so critical to ensuring success. It's also one of the toughest steps to master.
- Next, the clay is opened up. An indent is made in the center with your thumb and the walls are pulled out to the desired diameter. I also check the thickness of the base with a needle at this point.
- Now, we begin throwing, which means squeezing the wall as it rotates and lifting up slowly to compress and extend the cylinder. This must be done carefully as to not pull the piece off center. The goal is to reach the desired thickness and height in only a couple pulls, as to not overwork the clay.
- In the refinement step, you can use curved rib tools to shape the form to whatever curve you like, you can smooth the surface with rubber ribs, form the rim, and tons of other surface decorations too. You can get creative here!
- Lastly, the piece is cut off the bat with a wire, once it's dry enough to hold its form.
Most of this Instructable will use standard wheel throwing terminology like what was mentioned here, so it's good to get that out of the way early.
I will assume this much is understood.
But before we throw, we must make a YUGE bat!
Step 6: Phase I: Outer Pot - Cutting Out a Yumongous (Extra Large) Bat
The biggest bats we had in the studio were 16" in diameter, and my vessel was going to approach a 20" wide base, so I needed to get a bigger bat.
Or I could get crafty and make a bigger bat! So obviously I did.
The bat was made of an eighth of a sheet of 3/4" thick cheapo plywood. As as start, I marked off an approximately 20" wide circle with a sort of ad hoc compass - I took a 10" long piece of scrap wood, jammed a pencil into a hole drilled in one end, and hammered a nail into the other end and used it to draw the circle.
Ultimately the final bat would not follow this circle exactly but it was useful to get a sort of rough guide for the next step.
I cut about 2" outside of this line with a jig saw to get the rough circle shape cut out of the eighth sheet of plywood.
Then, I made an impromptu circle cutting jig on the band saw by putting a nail in a plywood board and clamping it to the band saw. Life Hack! Take a look at the sketch to see the basic concept. I drilled a very small hole in the center of the roughly cut circle and slowly turned it around the pivot nail to cut out a decent circle in maybe 10 minutes. It was not perfect, slow, and had a weird flat point, but it would be sufficient for my needs.
Step 7: Finishing the XL Bat
Bats can be made of non porous materials like sealed plastic, or porous ones like plaster, which have the added benefit that they naturally dry out the base of the clay piece for easy separation later on. However, although wood can absorb water, it also rots very easily, unlike plaster, so I decided to seal the bat with two coats of Minwax Helmsman Spar Urethane, a finish for sealing outdoor furniture, which is regularly exposed to the elements. This should provide a good enough layer of protection to prevent rot within the first few uses — not that I expect to use it again but hey!
I first set up a frame to lift the disk off the table for drying. This was done by screwing together pieces of scrap wood in an H shape, then putting four nails into the corners, and snipping off the heads with metal snips to get four very tiny points.
I then used a foam brush to put finish all over it. The benefit of this makeshift frame is that I can brush on both sides of the bat and let it dry on the pins with no fear of it sticking to the table. After drying overnight I went back and did a second coat, finishing sanded lightly while wearing a mask outdoors, and it was done!
Step 8: Attaching the XL Bat to the Wheelhead
Correctly attaching the bat is CRUCIAL to preventing bad accidents involving projectile wooden disks.
First, a flat suction disk is thrown on the wheel. Supposedly the ridges provide points for vacuum seals to be made. I don't know how true this is, but tradition says to do it, so ¯\_(ツ)_/¯
Then, the bat is slammed down onto the clay. When it's partially attached, right now, you can spin the wheel slowly and center the bat by pushing inward when the bat juts out until it's symmetric enough.
Use a hammer or your fists to hit the bat down as firmly as you can, just don't destroy your bones! The true final seal happens next anyways.
Look under the bat and use the wood tool while the wheel is spinning very slowly (turn by hand) to form a solid, continuous, curved seal between the wheel head and the bat. This is essential so that the bat is totally secured and has no place where it could spontaneously detach.
Step 9: A Fair Warning!
Another caveat! The extra large bat can be dangerous if used improperly.
If you accidentally floor the pedal, you'll have a rapidly rotating wooden wheel that could fly off at any moment, especially if the disk is dry or poorly attached, and could easily jettison your 30 pound pot straight at you.
When using the bat, you have to go very GENTLY and SLOWLY on the pedal, and you must constantly check the suction disk. If it's totally dry, there is no connection between the bat and wheel, and you MUST remove the bat and throw a new suction disk. You'll see what I mean later on.
Additionally, I did scrape my knees on the side of the giant spinning bat, which left some scratches. If it had been going faster, it could have been a nasty gash. Be warned and proceed with caution!
Step 10: Throwing the Base
As I am not the incredible hulk, there was NO WAY I was going to be able to center and throw 60 pounds of clay (20 pounds is hard enough) so I decided to build up in parts using the coiling technique.
A base is first made. I made this flat disk by centering and flattening about 10 pounds of clay into a uniform disk.
Looking back, I should have made the base a full inch thick. I only made it 1/2" thick at first and ended up going back in and attaching a flat sheet to add thickness, which could have been avoided by starting off thicker.
A quick note, all discarded clay I dropped into a container to be recycled and reused by soaking and then drying on a plaster slab later on.
Step 11: The Coiling Procedure: Extruding
Since I built using the coiling technique, I used an extruder to make the coils. To use this machine, which pleasantly reminds me of the play-doh tools kids use to squirt out spaghetti, a die is placed in the base, in my case a piece of plastic with a hole in it about an inch in diameter. When clay is loaded into the chamber and the lever is pulled down, the clay is forced through this hole and it comes out as a thick, round cylinder.
And yes, I am aware it looks like a doggy turd.
Moving on to more important matters... I then used my palms to squash the cylinder into a more flattened oblong shape, like a strip. This shape would better form the walls of the pot.
Step 12: The Coiling Procedure: Attaching
If there's one thing you learned from school art classes, it was probably the iconic "scratch and slip!" or "scratch and attach!" slogan. Even years later, this mantra holds true.
As a glue to bond clay, we use "slip". To make this, I blended chunks of the clay with some water in a blender until I got a smooth paste, and that's slip! It looks suspiciously like a luscious, smooth ice cream milkshake but I do NOT recommend you eat it.
Using a ridged metal rib, I made deep scratches on both surfaces: the rim of the pot and the edge of the coil to be attached.
Then, I spread a nice layer of slip into the mating surface of the pot.
Next, I pressed the coil onto the rim of the pot all the way around. At this point, the coil is not fully integrated; we'll discuss that in the next step so be patient.
A good trick I came up with if the coil was not long enough to go all the way around was to add on and join smaller coil sections by slipping and scoring those onto the ends. By making a V shape on each end, I increased the surface area for attachment and could make some solid joints.
Step 13: The Coiling Procedure: Throwing
To fully integrate the coil, first I used a wood tool to make deep diagonal smears between the pot and the coil. I did this once in one direction, then again in the other direction all the way around on both the inside and outside.
Then, I roughly smoothed the joint by spinning the pot with my hand and smoothing with a wooden rib.
Now that the coil is fully attached, it can be treated as part of the body, and so, I lightly wet the rim and spun the wheel slowly so that I could throw with it. By pressing gently and slowly, I could compress, make thinner, and make taller this section of clay.
This process was repeated about 8 times to build up to a 20" height. This was a time consuming process that took me about many days to get through, ~15 hours total.
Step 14: A Lengthy Selection of Tips
Apologies in advance for the wall of text, but:
- I cut the rim off every few layers with a wire to provide a flat surface for the next few layers. It's good to occasionally re center, adjust, and trim the rim of the piece to make it as centered as possible, because errors can propagate up as you add more layers, worsening if left unattended.
- Don't bother to try throwing the rim too much, just lightly compress and lift. If you make it too thin it can collapse or break. I made the rim around 1/2" thick.
- Only attach coils to a rim that is at a similar stage of moistness. Although a connection between a wet, soft coil and a leather hard rim might "look good" at the greenware stage, upon firing it will be revealed that the joint was a total failure and it will separate instantly. This normally means I wait around an hour after attaching each coil or blast with a heat gun so the freshly thrown rim firms up closer to the fresh-out-of-the-bag consistency of the extruded coils.
- Wait until the base of the pot is sufficiently firm and not too pliable before adding more coils. A floppy base is likely to warp or worse! collapse!! So be patient and wait for the right moment, or heat gun it.
- Every day, check the suction disk underneath the bat! If it is rock hard and chips away with a tool, there is NO CONNECTION there anymore and you MUST remove the bat, throw a new suction disk, and re attach the bat. I'm sure we're in agreement that it would not be fun to have a huge pot on a massive wooden disk hurled at us at high speed.
- Watch your knees! It turns out, the spinning wooden bat will easily scratch your knees. I definitely didn't learn this from personal experience. Of course not.
- Please don't floor the pedal. Please. Even with a low speed, the rim will be zooming past you. With such a large rotational inertia, it'll just take some time to get the big pot up to speed, so be patient. :)
Step 15: Do Not Fear the PADDLE
A great tool that is often overlooked is a wooden paddle.
When the profile of the pot is wonky, squinky, and not pleasing, you can wet a piece of wooden board and gently slap the parts that jut out all the way around, paddling until the shape becomes corrected.
Make use of the paddle to improve your shape as you build up the layers.
Step 16: Oops - Thickening the Bottom
Everybody makes mistakes!
I originally made the bottom too thin (1/2") and wasn't sure it would hold up, so for insurance I rolled out a 1/2" slab and slip and scored it on. This made the new bottom 1 full inch thick.
I then smoothed out the joint edge with a rib and used another rib to press down and fully integrate it.
Step 17: Oxygen Holes
Charcoal burns through a combustion reaction, which requires carbon from charcoal and oxygen to work. This means it's necessary to include some air holes in the base to allow new air to flow up into the charcoal chamber, or else the fire will die quickly.
The method to do this while the pot was still on the bat but leather hard was to use a small round circle cookie cutter, hammer it down to the bat with a mallet, then twist and pull up to take out the cookie cutter, which, if all worked out, would have the plug of clay stuck in it, which could be easily popped out.
This process was very satisfying!
It was repeated multiple times to get 12 evenly-ish spaced holes. It is not important to be totally precise here since you won't see them from the top anyways
Step 18: Adding a Rim
Once the pot was up to the right height, it was time to add a rim, which in my opinion provides a much more finished and classy look and crucial support for the donut lid.
In the end, the rim also ended up being essential as a place to hold on and lift the pot into the kiln.
The rim was added in sections by rolling out 1/2" slabs on the clay roller and cutting curved sections about 3" wide. You can use a rolling pin if you like.
The sections were simply slip and scored together and onto the rim. Unfortunately, some of the rim pieces were not well connected, meaning some visible cracks were visible on the rim once fired. Do a good job of making sure everything is well blended.
It is also important to reinforce the joint from underneath. Simply scratch and attach a coil under the joint and use wood tools to smooth the coil into a continuous curve joining to both the wall of the pot and ledge of the rim. While not obviously visible, this bead of clay adds immense strength to the rim and prevents people from accidentally breaking off the ledge when picking it up by the rim.
Step 19: Trimming
Now, the pot was let to stand in the open air for a few hours to air dry slightly.
To begin trimming, the clay must be leather hard meaning it is not wet, but also not rock solid. You might compare the firmness of the clay at this stage to a block of aged gouda: pliable but structurally solid, sliceable, not crumbly, although perhaps not as delicious.
The pot was set spinning while various ribbon tools were held to the surface to trim off ribbons of clay, much like a vegetable peeler peeling away thin layers to reveal a smoother surface.
Then, I used rubber ribs to slightly smooth the new exposed surface.
Step 20: Handles
I decided to add handles both for practical lifting purposes and a e s t h e t i c s.
I extruded coils and bent them to handle shapes. Then, I measured and marked four spots equidistant* from each other around one circumference of the pot, about 2/3 of the way up the pot. I wanted the four handles to be more or less symmetric.
Then, I repeated the age old technique and scratch and attached all four handles. I also went back in and attached reinforcing coils around each joint, smoothing the coil to a continuous curve with a wood tool for extra strength.
*well, equidistant enough apparently
Step 21: Surface Decoration - Painting on Underglaze
To jazz up this otherwise simple shape I chose to add some flourish with some surface decoration.
I wasn't going to fire the pot up to temperatures high enough to melt glaze, so glaze was not an option. Instead, I resorted to using under glaze, which is just colored slip. It would provide a nice contrast to the off white clay body once fired.
A thin layer was painted on in strips onto the surface while I spun the pot by hand. Several coats were required to reach opacity.
For the bottom section, I chose to attempt (and not really succeed at) an ombré look by going fully opaque on the top and trying to lighten up and fade into nothing on the bottom. It's not really noticeable but hey, it doesn't really look bad per se!
The slip eventually dries to the same consistency as the clay body, since they are both in fact raw clay, just of different colors. This means you can carve into it and make cool designs.
Once dry, I used a trimming tool to cut away the rough edges and make the band of color much cleaner. Sadly, the pot was quite lopsided, which made trimming it to the line like trying to wrestle somebody on the roof of a moving train car.
Nonetheless, from far away it looks clean enough.
Step 22: Surface Decoration - Sgrafitto and Chattering
For the upper band I employed a technique known as sgraffito, in which I used a mini ribbon tool to carve out the surface, revealing a simple geometric herringbone pattern below. Simple and classy.
For the bottom band, I used my personal favorite surface decoration technique: chattering. To chatter, the pot is set into rotation while I press an L shaped tool, actually a bent sharpened hacksaw blade, into the side. The tool bounces on the surface, cutting out a pattern of small short lines.
Chattering looks easy but the combination of pressure, angle of tool, clay dryness, speed of wheel, and profile and sharpness of the tool all contribute towards the final outcome. Getting the pattern you want takes a lot of practice, but the end result is a beautiful and fast ornamentation.
Step 23: Detaching the Pot
Detaching the pot was hard.
Because the pot was hard.
I tried using a wire cutter, but the clay was just too firm so I defaulted on the brute force technique: hammer flat knives / spatulas underneath the pot in many places until I could lift it up enough to separate the pot from the bat.
Turn off the wheel when you're doing this and try to avoid cutting up into the bottom layer of the pot, which introduces crack and weak points.
There may have been a better way to do this but this was the best I could do.
Step 24: Phase II: Inner Pot - Intro to Section Throwing
The inner pot is actually the most important part of the whole device, as it is where naan is slapped and the cooking takes place. The walls must be substantial enough to hold heat, around 3/4" thick.
The inner pot is made in two parts: the bottom which holds the fuel and the top which forms the main body of the cooking chamber.
For those not familiar with section throwing, to achieve great heights and large vessels, instead of centering enormous amounts of clay, potters can throw sections and slip and score them together. This technique was used to make the inner pot.
Step 25: Measuring and Designing
The large pot was first measured so that dimensions could be formulated. I chose to have the inner pot protrude a few inches above the rim of the outer pot so I could get just a little more volume inside.
I also chose to have the inner pot be around 4-5" away from the rim of the outer pot at all times to give ample room for the insulation. This meant I ended up with a cooking chamber about 10-12" in diameter, which is small, but enough to cook maybe 4 naan at a time and three tandoori skewers at once.
Step 26: The Charcoal Chamber
The charcoal chamber holds the charcoal*.
I added a section on top and pulled very small walls to make this double lip, in which the upper part of the inner chamber would sit. The inner rim also provides a ledge from the skewers, so that they don't go directly into the coals.
*who would have guessed..
Step 27: More Oxygen Holes
I poked oxygen holes in the base to work like a grill grate, providing points from which oxygen can flow into the coals, allowing the combustion reaction to continue.
I just used the small cookie cutters as well as hole cutting tools to make sporadic holes.
Step 28: Foot of the Charcoal Chamber
To lift the assembly up an inch or two off the base and allow for better air flow, I added a foot ring.
To prop up the charcoal chamber to do this without destroying the double rim, I pressed three chunks of scrap clay into a bat that would fit into the space between the double rims. This held up the chamber upside down, allowing me to scratch and attach the foot ring.
As you'll see later on though, there were several issues with my technique that caused problems down the road.
Step 29: The Upper Cylinder
The upper cylinder is basically a slightly bulging cylinder. Throw it bottomless.
I made this just like you'd expect, throwing multiple sections and attaching them together to get to the right shape.
Once again, I aimed for walls 1/2 to 3/4 inch thick to retain heat.
The paddle returns! I used the paddle once again to help correct the shape. The inside should be as smooth as possible so naan can easily adhere without falling off.
To add some class, and support for the lid, I attached a thin coil on the rim and smoothed it into a nice lip.
Step 30: Adding Skewer Rests
A bonus feature I chose to include was notches in the rim, which serve as places where a skewer can rest without all sliding down to the same point.
To make them, I first used this cool division tool, a plastic sheet with lines in it, to mark 12 points equally spaced around the rim.
Then, I used a right angle shaped piece of wood and pressed it into the rim to make a nice notch.
Not only do the notches provide functional use, but they look cool too!
Step 31: Trimming and Adjusting
I then moved on to making the parts fit.
I trimmed and smoothed the space in between the double rim of the charcoal chamber as well as the bottom rim of the upper pot until they fit quite well together.
As you can see, the bottom piece supports the upper perfectly!
Step 32: Phase III - Lids: Upper Lid
The uppermost lid was very simple.
A disk is thrown just larger than the opening of the upper pot. It is allowed to become leather hard, then cut off.
A ring of underglaze is painted on, dried, trimmed clean, then carved into a herringbone pattern with a mini ribbon tool to match the design on the pot.
A fun ergonomic handle was added out of extruded clay coils. After considering multiple shapes, this rounded triangle seemed appropriate, and felt good in the hand.
It was scratch and attached, and the joint reinforced with a coil as per usual.
Step 33: Throwing the Donut Lid
This "donut lid" was one of the hardest parts of the whole build.
From the sketches, you can see that it's sort of a section of a very wide, shallow cone.
I began by throwing a bottomless plate rim sort of shape, which sagged a lot. It was very frustrating to deal with.
I had to add blocks of clay below the rim to support it as it dried firmer.
Once dry enough to hold its shape I cut it off, and promptly realized it was too small on the outside.
Step 34: Extending the Donut Lid - Rolling Out Slabs
To remedy the size issue, I rolled out some clay 1/2" and cut into curved shapes.
Step 35: Extending the Donut Lid - Attaching Slabs + Reinforcing
Then, to extend the edge to make it wide enough, I set the lid right side up on the (reattached) yuge bat, supported by door stop shaped chunks of scrap clay.
I then scratch and attached those extension pieces all the way around, just like the rim was done.
Next, I added a coil on the joint and smoothed it out to reinforce.
Reinforcing is important!
Once the top was smooth, I propped the lid up on the scrap clay and attempted to smooth out the joint from underneath, which is tough, but as long as it's good enough it's fine. It won't be visible anyways, it just needs to be structurally connected as to not break off.
Step 36: Decorating the Donut Lid
To decorate the donut lid, I repeated the process of painting rings by brushing on underglaze while the wheel was spinning, and trimming the bands clean.
I then chattered the bands like I did on the big pot.
Step 37: Underglaze Inlaying My Signature
This method of putting my "signature" on the pot is a nice touch!
I chose to inscribe my logo with my artist name, the Left Handed Limaçon, on one side, as well as my name and the year of production on the other side so in the future I can look back and remember.
To inlay easily, I used waxed mishima.
- To do this, the area is painted with a thin layer of brushing wax. It dries in 5 minutes.
- Then, the design is carved into the area with a mini ribbon tool
- Next, the crumbs are sucked out with a vacuum or blown away as to not interfere
- Black underglaze is painted into the cracks
- The excess is naturally repelled by the wax!
- A damp sponge easily wipes away the excess which has beaded up on the surface
- Any not fully filled spots can be touched up with a brush
Step 38: Handles
Lastly, I added handles in the same manner as I did for the handles on the big pot.
Step 39: Test Fit Parts
Now, I test fit all parts to check that they fit together.
Success! On to firing!
Step 40: Firing
After doing some research, I decided it was best to fire the pieces to a temperature just lower than normal bisque, because it would leave the clay more porous and more resistant to heat, but high enough to still have a little strength. We went with cone 06 (about 1000°C / 1832°F).
This huge oven, the electric kiln, heats up and cools down over the course of days to bring the pieces up to temp.
Putting the big pot in the kiln was NOT easy.
We ended up going with two people holding the lid up while four people held just underneath the rim, where the clay was strongest, and just barely managed to lower it in. I am so thankful for all those who helped!
The rest of the pieces were fired in batches.
After a few days, the pieces would be cool enough to take out. After firing, they become an off white color and ring with a tone if hit. They are stronger too.
Step 41: Issues Reveal Theselves
Since I attached all three sections of the charcoal chamber at different stages of hardness, the joints, which looked fine in the greenware stage, failed!
It separated into four pieces easily.
I still managed to use it, however. Read on to find out how.
Step 42: Phase IV: Assembly - Setting Up the Base
I first chose a suitable location for the tandoor. My backyard has a sort of patio area full of pavers, and I chose to place the tandoor 1 foot away from one corner so that it would be close enough to have easy access to it, but also not invading the patio.
First, I dug up a 2ft x 2ft patch of grass and roughly leveled it. I placed four 12" x 12" red pavers in to serve as the stable base, which would support the tandoor and stop it from sinking into the earth. To get the pavers level, it was necessary to lift them up sometimes and toss in or remove dirt to make them sit without wobbling.
Then, I placed four single concrete cinder blocks in the center of each paver. These lift the pot off the ground, allowing air to enter through the air holes below. They won't get hot, and only have to provide structural support. In the future I would look for a better looking solution, as I'll admit the concrete cubes are not very nice to look at. Some people even place the assembly on wheels, but that's a whole project for another time!
Finally, I lifted the large outside pot onto the four blocks, and adjusted until it was mostly centered and the blocks did not block any of the air holes in the base.
Step 43: Assembly of the Pieces
Now to assemble the whole thing!
Now that the outside pot is in place and adjusted as to not rock about, the charcoal chamber is placed in the center of the base. As I mentioned before, my charcoal chamber suffered some truly tragic breakage during firing, so in that case, I placed in all four pieces of the charcoal chamber.
Here's the good news: turns out, even when separated into four parts, when arranged correctly, the piece is fully functional and supports all the weight.
Moving on, the cooking chamber was inserted right on top of the charcoal chamber so that it doesn't rock when moved. After checking that the assembly was basically centered, an entire 4 cubic feet bag of vermiculite was poured into the space between the outer wall and inner wall. If all works right (and it did) no vermiculite spills into the inside as it is a perfect seal. Success!
The vermiculite came just about 2 inches below the rim of the outer pot. A little more would be nice to close that gap but it's good enough for now. Most of the pot is now insulated.
Lastly, slap that big ol' donut lid right on the top to cover the vermiculite layer, protecting it from flying away, degrading in water, or getting contaminated.
1 month after beginning, you are finally ready to cook!
Step 44: Lighting Up
So, you may be asking yourself: "How do you use a tandoor?"
Since this article's goal is to focus on the designing, building, and assembly, I will direct you to my other article, a recipe for tandoori chicken and naan, which includes an in depth explanation of preheating, operating, and maintaining the cooking device:
I'll still include a brief summary of the process here though.
It turns out, it's not that difficult at all! I had decent success the first time, even though I was coming up to bat with a fat zero hours of experience.
I like to set a layer of crumpled brown paper in the charcoal chamber, toss two handfuls of good quality charcoal briquettes (not the garbage non lighting off brand charcoal) atop it, then light the paper with a match. The flames engulf the briquettes, lighting them.
There will likely be smoke from the smouldering paper for 20 minutes, but after that, it should dissipate.
Step 45: Preheating
I cover the top with the lid most of the way to contain heat.
The tandoor has to preheat for a full hour, there's no getting around this!
Clay heats very slowly, but once it's hot it stays hot for a long time, hours after the charcoal has died.
I use a nifty laser thermometer gun (best $13 I ever spent) to check the temp of the inner wall. When it's reached at least 250°C (480°F) it's good to go.
Throughout the process, in 15 minute or so intervals, I refill with no more than 5 briquettes at a time.
Once I got impatient and dumped a huge pile in there.
The clay suffered some tragic but luckily not structurally serious injuries.. so be patient! Better slow and steady than boom all at once!
As a safety feature, thanks to the double walled design the outside wall will never become more than lukewarm even after cooking for hours.
Step 46: Using the Tandoor for Naan
N A A N T I M E !
Naan, everybody's favorite leavened Indian bread, is a classic tandoori staple. Instead of being baked in an oven, they are cooked in a unique manner that gives them a distinct flavor and texture that you can't get from a regular household oven.
The dough is made like any other bread dough, with high gluten flour, yeast, water, salt, oil, and maybe some milk or yogurt. After rising for an hour, it's time to bake.
A "gadhi" or pillow is made first. I bought one online.
Next, the dough is cut into small balls, and stretched with the fingers to make a very thin, oblong, almond shaped sheet. The dough sheet is placed upon the gadhi.
Then, wearing a long sleeved hoodie and cloth gloves for protection, I hold onto the gadhi and carefully use it to slap the dough directly onto the inside walls of the tandoor. It's HOT in there, and kind of feels like shoving your hand into a hot oven, but for a few seconds, it's bearable and not at all painful.
The naan cooks in about 2 minutes. By then it will be puffed up, bubbly, and golden brown. The naan is detached by peeling it off the walls onto a long hook with a paddle. These tools are essential to get the naan off without accidentally dropping it into the belly of the beast, never to be seen again.
There is something so satisfying and unforgettable about the smell of fresh bread drifting through the air. It just makes you inexplicably happy!
Step 47: Using the Tandoor for Kebabs
K E B A B T I M E !
This is the easiest way to cook in a tandoor.
For the classic tandoori chicken, the meat is first allowed to soak up delicious flavors with a marinade made of salt, yogurt, oil, green chili, ginger, garlic, red chili, turmeric, coriander, and garam masala for several hours. It is then impaled upon long skewers and placed into the hot tandoor for 15 or so minutes until cooked and nicely charred. Beautiful.
You can check out my full recipe with tips on the other article I wrote, which is linked in the "Lighting Up" step of this article!
The chicken is cooked and covered in an delicious golden brown crust with savory burnt tips in 15 minutes or so. I check the internal temperature with a thermometer just to be sure. Serve with basmati rice and naan.
Step 48: Why Cook in a Tandoor?
What distinguishes tandoori cuisine from other cooking methods? Simply put — it's all science!
The screaming hot clay walls emanate radiant heat, just as the charcoal does, which contributes to delicious maillard browning on the outside of the skewered meat, creating tasty charred bits like a broiler might do.
By closing the lid, I create a mostly closed chamber of air that becomes extremely hot by convection currents which cook the meat through by slowly heating it up. This mechanism works exactly like an oven, hence why a Tandoor is often called a cylindrical clay oven.
The added benefit of the tandoor is that because of the design, the dripping juice and marinade falls directly onto the coals, where it burns instantly, creating smoke inside the chamber that penetrates the meat and gives the food a distinctly charred tandoori flavor.
As for the naan, there is first and foremost the fact that you're cooking on clay. Hot clay draws out moisture to create an unbeatable crispy crust. The side that's exposed to the hot air puffs up instantly because of the heat and then crisps up to become pleasantly crunchy.
A tandoor, like a pizza oven, also has the ability to reach temperatures much hotter than a home oven, which is responsible for a super fast cook time of 2-3 minutes.
Honestly, it's beautiful!
Step 49: Final Thoughts
It might have made more sense to write a book instead of an Instructables article considering the length of this, and maybe I will later on. (FORTY-NINE STEPS?!?!) And yet, I'm proud to post it here, where anybody on the internet can come and hopefully learn something from my process. There is not much free info online on what makes a good tandoor, how to design one, or how to build one from scratch, and hopefully I can fill that void with this article.
Although I spent a full month of "work" on this beast and a few hundred dollars, I regret none of it. The dozens of hours never felt like work, because I got to become an engineer, a designer, an artist, a potter, and a scientist. I stretched my abilities to the max making the biggest pot ever made in my school's studio, and tried my hand at becoming a tandoori cook by slapping hot naan. There were mistakes, but all fixable ones from which I learned so much.
This is why I love to make so much.
I'm proud that I was able to create a decent looking and fully functional tandoor to furnish the backyard, and can't wait to continue to host cookouts and bring people together by providing tasty chicken and fresh bread to my friends and family for years to come.
To find out about the next step, how to operate and use the tandoor to make the classic tandoori chicken & naan, head over to my other article which goes in depth on that subject. It's linked in the "lighting up" step of this article.
So, to all my tandoor builders, best of luck,
and to all else, thanks for stopping by!
of The Left Handed Limaçon
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