Introduction: Food-Safe Wood Finish With Shellac (+ Bee's Wax / Walnut Oil)
This Instructable will take you through the steps of making and applying a true shellac finish from flakes (not the stuff in the spray can or jar that you'll find at the hardware store, although the same steps may apply). Shellac flakes are dissolved in alcohol, then the mixture is applied to a piece of wood, the alcohol evaporates, and the shellac stays behind and seals the piece.
I needed to find a finish that was totally food-safe, quick to apply, low VOC, and easy to maintain.
While I understand most wood finishes are considered food-safe after they've cured, shellac is more or less edible. It's used in candy, pharmaceuticals, and is sprayed onto apples to make them shiny. Mmmmm ;) I don't really want to mess around with finishes that require a respirator, because I do a lot of the finishing at home in my workshop-kitchen space, and I don't want to take any chances on what may or may not be food safe because the pieces are being used day in, day out, by two restaurants in San Francisco. My health is one thing, but the health of strangers is another, so I gotta play it safe.
The client requested a "bronze finish" and gave me a sample of wood to match. The sample was walnut, but it had a reddish / gold tone that I wasn't familiar with. After wondering wtf this piece of teak-ish looking walnut was, a few old timers confirmed that the sample was indeed walnut, and I went from there.
I did some research and learned that shellac can be used as a sealer, which helps the wood from going really dark, particularly on the end grain. I made some samples using garnet shellac, and the results were really close to the sample they gave me. So I ran with it.
Since then I've been using it on all of the restaurant pieces that I make. They maintain the finish with a daily or weekly application of a wax/oil paste (Step 5) that I provide. They wash and dry them by hand, and after a year of daily use the pieces still look great.
What I like about garnet shellac is that it adds a richness to darker wood, where a straight oil finish tends to look dull. On lighter wood, like oak, it becomes a personal preference.
These links have very detailed information on shellac, particularly the second link, no need to cover it here too:
What is Shellac?:
Shellac is the resinous excretion of a female bug in Southeast Asia. It is cooked, filtered, reduced, and cooled into flakes and comes in three colors (ruby or garnet, amber, and blonde). You're most likely to find shellac premixed with alcohol in liquid form. To get the flakes you'll need to order online or make the trip to your local woodworking store (MacBeath Hardwood should stock it if you're in the Bay Area).
Shellac flakes have a longer shelf life, you have total control of the cut, and you know exactly what's in it.
Materials and Supplies:
- De-waxed Shellac Flakes
- Denatured Alcohol
- Plastic or Glass Container with Lid
- Stir Stick Thing
- Cloth Towel
- Brush / Cloth / Applicator
- #0000 Steel Wool / 400-600 Grit Sandpaper
Step 1: The Cut
Shellac can be used in different concentrations. More flakes dissolved in less alcohol will give you a higher cut. This will make each coat richer in color, but it can also be harder to work with.
3 lb. Shellac Flakes : 1 gallon Alcohol = 3 lb. cut
2 lb. Shellac Flakes : 1 gallon Alcohol = 2 lb. cut.
1 lb. Shellac Flakes : 1 gallon Alcohol = 1 lb. cut
For a brushing application, I've been using somewhere around a 1 or 1-1/2 lb. cut. It's easier to apply multiple thin coats rather than 1 thick and runny coat. I'm not usually measuring, just adding some flakes to the alcohol, stirring, and letting it dissolve. If it looks clear, I'll add more flakes. If it's hard to work with and too syrupy, add more alcohol.
Because I'm working with smaller quantities and don't need to mix up that much, I quarter the 1lb. recipe above. Add the alcohol first, then the flakes so they don't clump (Pro Tip from The Furniture Bible by Christophe Pourny)
- Add about 16 oz. denatured alcohol
- Add 1/4 lb. (4oz.) Garnet Shellac Flakes
- Stir in a few hours
- Stir a few hours later
It's recommended that you wait 24 hours for the flakes to completely dissolve, but even after half an hour, if you've been stirring every ten minutes, you can start applying it. Just be careful because 1 coat after half an hour won't look the same as 1 coat after 24 hours the next day. As it's fully dissolved, it should be be richer in color. This isn't a problem unless you're trying to make a bunch of pieces that match.
The alcohol will evaporate, so make sure to put a lid on the container when you're finished working with it. Plastic salsa / to-go containers work well, and so do glass jam jars and things like that. Shelf life of the shellac alcohol mix should be a few months. Storage of the dry flakes should be a few years.
Clean the brush in mineral spirits or acetone. Denatured alcohol should clean up any shellac that has dried.
Step 2: Preparing the Wood
While the shellac flakes are dissolving, you can get the wood ready.
Raise the grain:
Depending on the type of wood, you may want to 'raise the grain' by getting the piece damp, letting it dry, and then sanding with 220 again. This can also be done after the first coat of shellac using 400 grit sandpaper.
Remove the dust:
If you have an air compressor, blow the piece off to remove the dust. If not, use a clean cloth. You can run with the grain, but sometimes that snags something and rips a splinter out, so I try to rub in tight circles. This depends a lot on the wood.
If you're in a hurry, you can get by without removing every last bit of dust. I do a quick wipe down and the rest of the dust just kind of disappears into the first coat.
Step 3: Brush It On
About your work space:
Ideally the work space is dust-free and not too hot or too cold or too breezy. The worktop and the floor is going to get dripped on, so put something down to make clean up easier.
No real concerns, but if you're working on boxes like this, or anything you need to hold by
hand, your fingers will inevitably be covered in shellac after a while. It's not too hard to clean up with some scrubbing, but you might wear gloves. Obviously it smells like denatured alcohol, but that doesn't bother me too much.
I'm getting good results with cheap chip brushes, but I'm just throwing them away when I'm finished, so not the best way... I don't really like the foam brushes, but they'll work. I find that they start to break apart after a while and leave pieces of fuzz in the finish. Sometimes the chip brushes drop bristles, but it's easy to pick them up. Harder to pick up the fuzz.
Dipping the brush in alcohol to the handle and then ringing it out should make it easier to clean, but I keep forgetting to do this.
You can also use a sponge, cotton cloth, or french polishing pad to apply shellac. On these boxes and similar sized bowls, I'm using a 1-1/2" wide brush. For larger surfaces, use a wider brush.
Brush it on:
- Dip the bristles 3/4 of the way in shellac, wipe off the majority on the rim of the jar, do the other side the same way, then brush it on - going with the grain.
- Overlap the brush strokes.
- Work quickly!
- The first coat should soak right in.
- Don't let the shellac build up on any part of the piece. Move it around with the brush and keep the first coat even.
- For the boxes I found it easiest to do the bottom of the inside first, then the top rim, then the inside walls, then flip it over, do the outside walls and the base, flip it over again to check for runs on the inside, brush them around, and finally lean it against the wall and lightly brush over the places where my fingers were.
- Tipping the piece up against something is a good idea because it will want to stick on big, flat surfaces.
- Watch carefully for runs a few minutes after you put the piece away! Brush in the run and flip it over if that happens.
Let the first coat dry:
- You'll be amazed at how quickly the first coat will dry. In 5-10 minutes it should be ready for the next coat. If it's still tacky, wait longer.
- The last picture here is after 1 coat. You can see that there are some lighter spots, and the finish is uneven.
- This is a process, and you'll almost surely need more than 1 coat to get a uniform finish.
Did you raise the grain?
- If the piece feels fuzzy, when it used to be smooth, you raised the grain. Congratulations! Lightly sand it down with 400 grit, blow or wipe off the dust, apply another coat. Repeat.
- After each coat, you can sand lightly with 400 grit or sand with a bit more pressure with #0000 steel wool to give the next coat something to bite into.
- I don't want to sand between each coat because it takes so much time when I'm doing so many pieces, so I've been applying 3-5+ coats of shellac and moving on. I haven't had any issues with the coats adhering to each other...
- After the piece has the tone, color, and buildup that you want, it's time to move on. Skip the next step if you like what you see and want to keep the glossy finish.
Step 4: Satin Finish
To get a more natural, satin finish - knock down the gloss with #0000 steel wool. 400 or 600 grit sandpaper will also work, just don't use too much pressure, and if it gets gummed up, use fresh sandpaper.
Be careful because with enough pressure and time you can burnish down through the coatings of shellac. If the piece is going to get a lot of exposure to moisture or water, you might just skip this step to maximize the shellac buildup.
Steel wool gets really messy, not just wood dust, but wood dust and metal dust. Plan and clean up accordingly.
Step 5: Making Oil/Wax Paste Finish
This paste wax is a variation on "A recipe for one sweet finish" by Jim and John Lakiotes for a food-safe salad bowl finish via Fine Woodworking.
I like walnut oil because it will partially polymerize. Over time it will harden, where mineral oil always stays oily. Because the paste wax is being buffed on and buffed off, it probably doesn't matter that much, but walnut oil also smells nice and isn't petroleum based.
5 parts Walnut Oil : 1 part Beeswax
- Warm oil on medium heat in a pan
- Stir in bee's wax until melted
- Pour into glass or wood container (NOT plastic!)
- Refrigerate or allow to cool at room temp
Apply the paste wax/oil with a cotton cloth and let it soak in. Buff it off with another cloth and maintain the finish as often as necessary (varies depending on use). This is the maintenance layer.
Step 6: Finished Piece and Other Uses
Shellac also has other applications too, like coating twine, chord, and cloth handlebar wrap on bicycles.
I wrapped the handle on my coffee machine with twine. It always unraveled until I put a few coats of shellac on it.
Same idea with the Japanese marking knife.
The wrap on the kettle was always coming loose until I put a few coats of shellac on it.
Those aren't my handlebars, but you can also use it to coat cloth handlebar tape on your bike. Over time it will wear away, but when that happens you can just apply another coat.
I hope this instructable inspires you to work with shellac!