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Make friends with this beautiful and versatile finish
I was recently asked to judge a carpentry show. One of the best pieces was a beautifully constructed grandfather clock. Unfortunately, a quick brushing of the polyurethane spoiled the look of the watch. The creator of the watch said he chose polyurethane for protection. But how durable should a coating on a grandfather clock be? Why put a finish originally designed for floors on a beautiful clock? What a difference shellac would have made. Don’t get me wrong, polyurethane is a great choice for high-wear surfaces like a desk or kitchen table top. However, I find that people use poly by default simply because it is readily available and durable. But is durability the only thing that matters? There are many other considerations that make shellac a great choice for adding beauty and protection to your projects.
Many carpenters have left frustrated after trying shellac. It’s a unique finish and there are some basic ground rules to follow. The tips in this story cover the basics that will get you on the right track.
THE MANY ADVANTAGES OF SHELLAC
- Non-toxic: Shellac is the safest finish you can use. It is an FDA approved natural organic material for coating apples, candy and pharmaceuticals. When mixed with pure grain alcohol, shellac is completely free of toxic chemicals.
- Repairable – A damaged or worn shellac finish is easy to restore or repair.
- Rubs well: shellac is harder than most finishes, including polyurethane. The hardness gives excellent rubbing qualities.
- Excellent Moisture Barrier – If you want to keep wood movement to a minimum, shellac can’t be beat.
- Quick drying – This means fewer problems with dust settling on a wet film. You can usually coat in under an hour for a quick build.
- Universal Sealant: Dewaxed shellac can be used as a sealant coating under almost any finish.
- Less sanding – Shellac does not require sanding between coats to make one coat stick to the other.
Should you buy waxed or dewaxed shellac? Wax occurs naturally in shellac. If shellac will be the only finish, then shelalc with wax works well. Wax decreases resistance when stuffing or brushing on shellac. If shellac is used as a primer or primer for other finishes, choose the dewaxed version to avoid adhesion problems, especially with polyurethane. Dewaxed shellac also has greater transparency and is more resistant to heat and water. You can de-wax your shellac by letting the wax settle and pouring in the clear waxed part.
The next decision a shellac buyer makes is color. A good rule of thumb is to use darker colors on darker woods and lighter colors on lighter ones.
Shellac is a natural product obtained from the excretions of the lac beetle. Shellac is available in colors ranging from dark reddish brown to a golden amber color depending on the time of harvest and the degree of processing.
There are five commonly available grades of shellac, from the least refined to the most refined: Seedlac, Buttonlac, Garnet, Orange and Super blonde. Seed-Lac is simply collected from the trees, washed and dried. It still contains leaves, sticks and parts of insects. Buttonlac has been filtered out a bit. It has a rich dark brown color. Garnet is a bit lighter and has more red than Buttonlac. Orange shellac is probably the quality most familiar to consumers. Super Blonde shellac is the finest. It has most of the color and all the wax removed. All dry shellacs must be filtered through a fine filter after mixing.
THE RIGHT MIX
Using shellac that is mixed too thick is mistake No. 1 that people do. Always dilute shellac to a cut of 1-2 pounds before use. Old-time carpenters used pure ethanol, or “spirits,” to mix their shellac. Pure ethanol is still sold in liquor stores in some states as “Everclear” ($ 20 per liter). Make sure it’s 190 proof stuff. When mixed with dry shellac flakes, Everclear produces a completely natural, non-toxic finish (safer than any water-based finish). When the liquor store cashier wonders where the hell am I going with a 190 proof case of Everclear. I’m just saying I’ll crash!
Denatured alcohol is the most common solvent for shellac. It costs a lot less than Everclear. It is essentially ethanol contaminated with another chemical to poison or “denature” the ethanol. This saves you from paying an alcohol tax.
Special alcohols that do not contain water (200 degrees) are also available. These alcohols are mixed to dissolve the shellac a little faster and dry a little slower, so it has more time to level out.
MILL YOUR BOWS
Shellac flakes take some time to dissolve. When my shop is fresh, I had to wait more than 2 days. Too often I failed to plan ahead and was forced to wait for my shellac to dissolve before the work could proceed. You can greatly reduce the time it takes to mix shellac by grinding the flakes. A simple blade grinder does the trick.
Warm temperatures also speed up the process. If your shop is cold, find a warm place to mix the shellac. I am known for putting a can in my car on a sunny day. In an hour or less, the earth flakes are completely dissolved.
SMOOTH THE FINISH
The brushed shellac can “window glass”, leaving the edges thick and thick. It can also “orange peel” when sprayed. This happens more often with a heavy mix; so keeping shellac thin (1-2lb. trimmed) is your best defense. If problems persist, try some “Shellac-Wet”. Just a few drops in a liter of shellac will greatly improve flow and leveling. Do not use this additive if you plan to coat shellac with a different finish as it may cause adhesion problems.
READY TO USE
Zinsser’s “Amber” shellac is a ready-to-use orange shellac and their “Clear” shellac is a blonde shellac. Both of these products contain wax and are mixed to a 3-pound cut which should be diluted into a 1-2-pound cut before use. “SealCoat is a 2-pound cut of waxed blonde shellac. SealCoat is a universal sealant that adds just the right amount of warmth and color under a water-based finish.
Mixed shellac has a shelf life of 6 months. Zinnser found a way to extend the shelf life of premixed shellac to 3 years. Always look for the date of manufacture on the can before buying. All three products are also available in practical spray cans.
QUICK MIX SHELLAC
For quick repair jobs, or for those times when you haven’t mixed enough shellac there is “Gold Dust”. It’s basically pulverized shellac. The powder is designed for repair jobs where quick, no-wait mixing of small batches can be beneficial.
CHECK YOUR HAIR
Most carpenters are used to buying finishes with the desired sheen (glossy, semi-gloss, satin or flat) directly from the shelf. With shellac you have a choice: high gloss. Traditionally, the luster of shellac was changed by rubbing it. Shellac is easy to scrub to achieve a smooth glass finish with the desired sheen. However, carved or heavily patterned surfaces can be difficult to erase. Thankfully, you can add a flattening agent like Shellac Flat to adjust the shine. Shellac Flat is made with amorphous silica and alcohol.
MIX SMALL LOTS
I make shellac in small batches, so it doesn’t go bad before I can consume it. The shelf life of mixed shellac is about 6 months. After that it will not dry properly.
I use a small scale (available at grocery stores) to weigh the flakes. To mix half a liter of 1-pound cut shellac, dissolve 2 ounces. shellac flakes in 16 oz. of alcohol. For a 2 lbs. cut, double the flakes. After the shellac has completely dissolved, strain it through gauze or a fine mesh filter to remove impurities.
Shellac is easy to color. Whether you’re looking for a deep, soft brown or a garish cadmium yellow, shellac can handle it. Just add an alcohol-based dye. For pure colors, super blonde shellac works best.
USE THE RIGHT BRUSH
Using the right brush is essential if you want your relationship with shellac to start off on the right foot. An inexpensive oval brush, such as the Biestt-Liebco # 12 shown here, is perfect for applying shellac to trim jobs and patterned edges. The natural porcelain bristles easily envelop the contours without leaving large drips. Golden Taklon is a fantastic synthetic material used on brushes such as the Athena 7100 series. The bristles are wonderfully fine and soft giving you a precise edge and control.
A high-quality badger hairbrush with a chisel edge is a great brush for applying shellac to a large, flat surface such as a table.
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