Introduction: Leather Rocket Backflow Incense Burner
I discovered the concept of backflow incense cones and burners recently after I had been commissioned to make a cone incense burner – which led to this white lotus flower project made with leather. I really love the concept of those incense burners which design is made to play around with the flow of smoke. It is a reddit post about a ceramic rocket burner that led me on the way to the design that we will be making in this tutorial.
After some initial research, I decided to try to replicate the rocket from the animated movie Wallace & Gromit: A grand day out as it reminded me of my childhood. Furthermore, the roundish design of the rocket with its big door on the side was quite ideal for what I had in mind.
Here is a list of international suppliers to help you procure the necessary tools and materials.
- North America:
None of the links are affiliated and all the companies are reputable and non-monopolistic.
Step 1: Requirements
- Mallet or hammer
- Stitching awl
- X-acto knife
- 3.5m hole punch
- 2 needles
- Wooden edge slicker or a piece of clean cotton rag
- Applicators for the dyes (I use Q-tips for the edges and pieces of cotton rags for the rest)
- An old brush to apply the glue and the Tokonole
Bill of Materials
- 4 oz veg tanned leather
- A piece of metal screen
- Water based dyes (white and red)
- Leather cement
- Leather conditioning product
- Tokonole (optional)
- Thread (866 linen thread au chinois in that case)
Step 2: Printing and Cutting the Pattern
Print the pattern on A4 paper and cut-out the pieces of the project.
Make sure that the pattern is not resized by checking your print settings. You can check if it was printed properly by measuring the test box on the pattern to ensure that its sides are 5cm long.
Tip: Print on thick paper to make it easier to trace the shape on the leather. 200g/cm2 and above is ideal (as long as your printer can handle it).
Step 3: Tracing the Pattern Pieces Onto the Leather
Use the awl to trace the outline of the different pieces of the pattern on the leather and mark the location of the stitching holes.
Some parts of the pattern have to be duplicated. Here is the detail of how many pieces you should trace for each:
- Part A x3
- Part B (without marking to position the window) x4
- Part B (with marking to position the window) x1
- Part C x1
- Part D x1
- Part E x1
- Part F x1
- Part G x1
- Part H x6
- Part I x1
- Part J x1
- Part K x1
Tip: The solid lines indicate cutting. The dashed lines are indications to help with positioning the pieces that will be glued on top.
Step 4: Cutting-out the Pieces That Will Form the Rocket
The leather pieces
Use an X-acto knife to cut-out all the pieces of the rocket.
Make sure to keep the inside piece of parts C (which will be the window) and E (which will be the door).
The metal screen
With a pair of scissors, cut a circle with a diameter=10cm in your metal screen.
This piece will be the surface onto which the incense cone will be placed to burn (thus the use of metal so that it can withstand the heat).
Step 5: Double-layering the Fins, the Door and the Knob
We are going to double some pieces to make them thicker.
The pieces in question are the 3 fins (parts A), the knob of the door (part G) and the door itself (inside cut-out of part E).
In order to do so, roughly trace the outline of your pieces on the rough side of your piece of leather. This will help us know where to apply the leather cement.
Then, apply leather cement to the rough side of the cutout pieces as well as to the areas that you have marked on the rough side of the piece of leather.
Glue the cutout pieces on your main piece of leather.
Tip: You can use some kind of roller (I used a coffee cup) to apply pressure and insure a strong bond between the two layers of leather.
Finally use your X-acto knife to cutout the double-sided pieces, using the edges of the first layer as a guide.
Step 6: Dyeing the Leather
Only the window (inside cut-out of part C) has to be dyed white. All the other pieces will be dyed red.
Get some dye on your applicator (a cotton rag in my case) and apply it to the different parts. I like to make a first pass using vertical motions, a second one with horizontal motions and a third with circular motions to insure that the dye is evenly distributed and avoid leaving marks.
Don’t forget to dye the edges. I usually use a Q-tip that I dip in the dye and roll over the edges in order to do so.
It is not really necessary to dye the backside as it will not be visible when the door of the rocket is closed.
Step 7: Burnishing the Edges
Use the method of your choice to burnish the edges. Burnishing basically consists in creating friction over the fibers of the edges to make them stick together, creating a clean and slick edge.
You can start by using sandpaper to smooth out any irregularities. Since I am using second-grade leather, in my case it is unnecessary to do so as it would only fray the edges even more.
The method that I am using consists in applying a coat of Tokonole to the edge with my brush, and then rub the edge slicker swiftly against the edge in order to develop the necessary friction. I start with the narrowest grove and make my way to the widest one.
Another method would be to apply water instead of Tokonole and to rub a little cotton rag to obtain the necessary friction.
Step 8: Assembling the Window, the Door and the Fins
To install the window, start by scratching-out the area where it is destined to be glued on part B (this is to ensure that the cement can penetrate the top grain and provide a good bound).
Then, insert the white cut-out of the window back into its circling frame (parts C).
Apply contact cement to the backside of the window, as well as to the receiving area on part B. Position the window carefully and apply pressure to glue it in place.
Use you awl to perforate the stitching holes, using the marks left earlier as a guide.
Stitch the window to the panel using a regular saddle stitch.
If you are using polyester thread, finish your stitch by melting the two thread endings on the backside. I am using linen thread here so instead I made a knot and apply a little bit of glue to secure it.
Tip: As a rule of thumb when saddle stitching, I measure a length of thread equal to the distance that I have to stitch + a very fair margin and multiply it by 3.
Use the same procedure to attach the knob (part G) to the door (inside cutout of part E).
Stitch it as you would a button on a shirt.
To stitch the fins, first perforate the stitching holes with your awl. Then start stitching using a regular saddle stitch.
Only two of the sides have to be stitched for now, as the third one will be used to attach the fins to the panels of the rocket.
Step 9: Preparing the Pieces for the Final Assembly
Perforate all the remaining holes marked earlier with your awl.
Do the same on the bottom piece K and punch the exhaust holes with the 3.5mm hole punch.
Step 10: Stitching the Top Panels to the Center Band
Start by stitching all the top panels (the 6 parts B & D) to the central band's topmost stitching line using a saddle stitch.
Feel free to arrange the window and the door differently. I thought that it would look better having them spaced consistently (2 empty panels in between) but you can absolutely choose to do it otherwise.
Secure the end of your stitch on the rough side. Back-stitch through two holes and insure that both your threads end up on the rough side.
Tip: If you are stitching with polyester thread, secure the thread-ends by melting them with a lighter and smear the melted blob on the rough side of the leather. If you are using linen thread like I am, you can end on a triple knot and apply a little bit of glue on the knot to secure it even more.
Step 11: Stitching the Bottom Pannels to the Center Band
When the top panels are stitched, move on to the bottom ones (the 6 parts H) and repeat the same operation using the bottom-most stitching line of the central band and the top-most stitching line of the panels to join them together.
Step 12: Stitching the Panels Together
Now to join the panels together, start your stitching line at the top to start joining the two left-most adjacent B panels. With a “reverse” cross stitch, make your way down all the way to the bottom of the H panels.
A reverse cross-stitch consists of following the normal procedure for a cross stitch (see the video that I linked in the required skills section), except that instead of doing the X pattern on the visible side of the leather, it is done on the inside leaving a stitch looking like this = on the visible side.
Tip: For a cross stitch like this, I measure a length of thread equal to the distance that I have to stitch + a very fair margin and multiply it by 5.
Every other panels pair, you will have to stitch a fin in between the two panels. In order to do that, use the same stitching technique except that you will pass the thread in the hole of the fin before reaching the other panel. You should start threading in the fin thusly 10 holes away from the last one at the bottom of the H panel.
At the end of this step, you will be left with only one edge open. Don’t stitch it closed it just yet.
Step 13: Stitching the exhaust
Now we need to add the exhaust piece. Stitch it all around using the same stitching method as you used to join edges together.
Then start stitching up the edge and stop your stitch line halfway up the rocket side. This way we can hide the knot under the central band and leave an opening to insert the metal screen because closing the rocket.
Step 14: Setting-up the Metal Screen Inside the Rocket
Insert the screen vertically through the remaining open edge and rotate it inside to secure it horizontally in the middle of the rocket.
Tip: I inserted a barbecue skewer through an exhaust hole to help positioning it by applying a little pressure from underneath when it was necessary.
Step 15: Closing the Rocket
You then want to stitch the top of the rocket just like we stitched the exhaust and continue stitching down the edge to eventually close the rocket completely.
Once again you can hide the knot under the central band and apply a bit of glue if the end-bits of the band are a little loose to make it look like a discontinued look.
Step 16: Applying Conditionner
Finish your rocket by applying leather conditioner on the entire piece and wait for it to be absorbed and dry to the touch.
Congratulations, you’re done!
Step 17: Operating the Incense Burner
Ideally you will want to use those special back-flow incense cones (they differ from regular incense cones because they have a cavity running down the middle which allows the smoke to flow backward because of...some kind black magic probably. Or physics. Nobody knows.
However if the panels were stitched very tight the smoke won't have anywhere else to escape but through the exhaust at the bottom so it should function as well with a regular incense cone albeit less effectively.
Back to the main topic. To operate the rocket:
- Remove the door.
- Light up your incense cone outside of the rocket.
- Insert the cone inside of the rocket. If your fingers are not especially thin you might want to use a pair of scissors to carefully pick up and lay the cone in the middle of the metal mesh inside.
- Put the door back in place.
Step 18: Post-scriptum: Making-of the Pattern
I thought that I would be a good idea to write a few words about the design process as I think that it could be useful for other leather workers out there. Indeed, my initial problem was the following: how was I going to design a functional leather pattern starting from a reference image of the animated movie’s rocket?
After some more research and trial and error, this is what worked for me. I hope that some of you will find this process useful for their own project.
1. Designing the rocket on Blender
The first step was to create a 3D model of the rocket, using an image of reference as a guide. After trying different programs (Sketchup & autoCAD), I found that the workflow and the tools offered by Blender were by far the easiest for me to assimilate and work with.
I designed two different versions: one as close as possible to the original rocket which was built around 12 faces, and another one for which I halved the faces. I anticipated that the 12 faces version would be a nightmare to stitch, as well as be problematic regarding the size of the door (indeed, one of the requirement was that the door should be big enough to insert the incense cone through it).
The following Youtube videos were very useful to learn the skills required to complete this step:
- Create paper models with Blender
- First steps | 3D Modeling with Blender for Cosplay
2. Printing and assembling paper models
Next I wanted to try out the models “IRL” to get a sense of the dimensions and of what would be the assembly process, all this without using precious leather as of yet.
In order to do this, I used the life saving “Export paper model” add-on in Blender.
On the model, I defined which edges should be separated and ended up two clicks later with a PDF representing resulting the paper model ready to be printed.
Following the numerical help automatically generated on the paper model, I then assembled the two versions of the paper rocket.
The result was thus: if the rocket made up of 12 sides was indeed more visually pleasing, it would not be practical from an assembly standpoint. So I decided to go with the 6 sides version.
3. Designing the pattern
At that point, going from paper model to proper pattern was very easy. I exported the paper model in SVG and imported it in Inkscape.
There I removed all the unnecessary parts that were used to assemble the paper models and used the offset tool to create the stitching lines.
A few manual adjustments later and the job was done!
First Prize in the