How do you shellac old furniture?

How do you shellac old furniture?

Shellac, which was used before 1930, is found under varnish or painted surfaces. 

You cannot use lacquer because it contains too many organic solvents that are poisonous in their dispersed form after using even small amounts. 

So you must either sand off old shellac enough to get down to bare wood. (using steel wool or sandpaper – steel wool works faster, of course), then use BONA Wood Cleaner (not water-based) to remove any oil (e.g. hand oils) and dirt particles, clean the surface with TSP (sold as walls cleaner in hardware stores) which is trisodium phosphate.

NOTE: Do not allow any liquid to soak into the wood; you do this by either applying thinly and wiping off quickly or using a spray bottle (do not inhale fumes); let stand at least 30 minutes for compounds like shellac. 

Apply thinner after cleaning again with lintless cloth/towel that will not leave fibers behind on warmish surface; wipe off excess, then wait for it to evaporate (15 minutes or more; you want tacky surface); this is called “blocking.” You can wait overnight if the finish will tolerate it.

If you don’t know what shellac type was used

If you don’t know what shellac type was used, generally, you mix one part of powder with three parts alcohol by volume – 3 oz. of shellac to 1 quart of denatured alcohol (methyl hydrate) or ethanol (ethanol = acetone-free vodka). 

Mix thoroughly with your stirring rod, using a metal container, so as not to introduce impurities into the finished product. 

Shake well before using because particles tend to settle on the bottom – especially important when working outdoors in a high humidity environment where some batches may be more viscous than usual due to moisture content in the air combined with the warmer temperature inside the container.

The can should have instructions on how to thin but generally, you add about 1 oz. of shellac to 1 quart of denatured alcohol or ethanol (methyl hydrate) or ethanol (ethanol = acetone-free vodka). 

If using pure methyl hydrate, mix by volume rather than weight. Shake well before using because particles tend to settle at the bottom – especially important when working outdoors in a high humidity environment where some batches may be more viscous than usual due to moisture content in the air combined with the warmer temperature inside the container. 

NOTE: For simplicity’s sake, let’s assume you are making 1 quart at a time instead of much smaller quantities which will require constant mixing and waste product. 

This is because it is not practical for most home users who only want to refinish one antique tabletop. Also, mixing 4 oz at a time is okay but not practical for larger quantities; in that case, you must adjust the amounts accordingly by multiplying or dividing (e.g., if I wanted 16 quarts, I would divide 16 by 4).

Generally speaking, when brushing shellac onto bare wood (no previous finish), you do NOT thin it beyond “spooning” consistency. (this could be considered about 10% or 1/10th in volume thinner or even less); this is because shellac dries very quickly, and brushes need to be scraped within seconds after application, due to the high sugar content in pure shellac (a resin secreted by lac bug – better quality = thicker resin). 

It makes sense to add a few drops of Floetrol or a similar paint conditioner per quart to prevent the brush from snarling, and to make application easier. 

It also inhibits the tendency for lighter coats to dry faster than thicker ones since they will take longer to dry. 

This can be a problem if you are not used to applying shellac because it dries quickly. Especially in warm weather, which means less time for brushing back and forth without leaving visible marks (sanding is required). Whereas old-timers I have talked with who do this work all year round say, “It’s impossible unless you learn how.”

You should start brushing on one side of the tabletop only so you get an idea where the legs go; this is done by using either scrap wood on the underside or just flipping the top over. Once you get to the other side, you will have a better idea of where the center is because the legs should be symmetrical on either side of the center hole.

You want about 3 medium coats, but it will depend on wood being used – best starting with lighter coats so as not to create drips while building up darker colors. If you are not sure how much shellac to use, practice mixing one can at a time until you get it right. 

You cannot re-use leftover mixed shellac since it becomes contaminated with dust/lint that gets absorbed into the mixture. Which makes it too thick after a while, especially if stored for later use in warm weather months (if kept cool in the basement or garage, this is less of an issue). 

If it gets too thick, add a little denatured alcohol, (fingernail polish remover) and stir.

Once you get the hang of using shellac, you will be able to apply anywhere, from 1-3 coats per day, depending on how much sanding is required between coats. 

Also, weather conditions can play a big role in making drying times longer when the moisture content in the air is high (humidity). Shellac does not dry by evaporation like lacquer. So humidity has no bearing, which means it dries slower than lacquer under the same conditions. 

It can take up to 3 days for initial coatings to cure/harden enough so that sanding is possible without gumming up the sandpaper and long periods where glue cannot be used. 

Once initial coatings are sanded. It should only take a few hours to dry/harden enough for subsequent coats of shellac, and then another day or two after that before applying lacquer. (lacquer must be applied within 24 hrs. Otherwise, wait at least a week).

Shellac does not sag like some lacquers, especially if thinner is used. But either drips or runs can happen if you apply too fast, so do not try to speed up application time by brushing back and forth unless you get good at it. 

If runs start happening, immediately stop and let it dry, which could take 15-30 mins but no more, as it will cause uneven drying. Which results in orange peel texture when sanded smooth (start over again with fresh shellac).

Shellac is your only choice when using dimensional lumber (plywood) because there are no suitable primers available for use with softwoods. 

If you have to prime plywood with something else, let the wood sit at least a week before applying shellac otherwise it will soak in and not adhere properly, which means you may have to sand it smooth anyway. Shellac sticks to just about everything, so go lightly on wiping down with Naptha or denatured alcohol unless it is extremely dirty then wipe several times with a damp cloth. Then dry thoroughly before applying the first coat of shellac.

On older tables, I prefer doing a half table at a time for test purposes – leave legs off until after the initial coat dries completely. Since they are often filled with dirt and need to be cleaned before the first coat of shellac is applied. 

I also do not use a wire brush on table legs if the wood is soft because wires will dig into the wood leaving grooves that end up looking worse than a few minor dents after the first coat of shellac has been applied, which covers them up. So it’s best just to pound out those dents with a rubber mallet, fill holes with thinned-out shellac, wait for this to dry, then sand smooth.

Tabletops usually have one or more pieces of veneer on top, but some may have more than one layer. This means you cannot sand through these layers as they are very thin, and plywood underneath will chip/break off when being removed by hand.

If the veneer is in bad shape it can be removed by heating the corner of the scraper with a propane torch, then peeling off the veneer. – This works well on older tables but not so much on newer ones since many are glued into place with waterproof glue, which makes veneer difficult to remove, especially if many coats of shellac have been applied.

Veneers that will probably come off without too much trouble:

– mystique/veneer that has large open pores and is somewhat brittle or “chalky” and easily scratched or dented (can be sanded smooth)

– no matter what table you have, veneers along the outer edge near legs tend to come to lose easier than those on top of a table that is under heavy load. So edge veneers come off frequently when putting on a new finish.

– typical satin finishes can be sanded to a semi-gloss which is the same type of veneer or “veneer blend” used in most newer tables

Veneers that will probably have to be removed using a heat gun then replaced with another, more suitable veneer:

– thick paint/lacquer coatings (strip off old shellac coats first)

– solid color stains over bare wood especially dark ones since they block light even after shellac has been applied and darkened. This makes it difficult for anything else to show through – if this happens, use chemicals such as oven cleaner, lye, or ammonia to remove paint/stain, then sand smooth and apply shellac again.

Veneers that will probably need to be removed:

– if the veneer is falling off, you can try heating the corner of the putty knife with a propane torch and gently working it underneath, glued on a piece of veneer, then prying off piece bit by bit, until the entire veneer has been removed. – be careful not to burn plywood if this happens.

– clear coatings such as lacquer which is what finishers use on new tables make shellac look cloudy plus it feels very slick when rubbed with your fingers. So applying more layers of shellac over this is next to impossible without removing the clear coat first. Shellac sticks to just about everything except clear coat.

– touch up paint, such as anything made by Purdy or Armstrong, are often oil-based enamels or lacquers that will not stick to shellac at all. I usually find out when trying to remove them with Naptha, which will bubble up around spots where the touch-up paint is present since it repels Naptha.

The trick is learning how to distinguish between different types of veneer and knowing if they can be sanded smooth after being stripped off. Or must be replaced with something else. – 

Unfortunately, there are no hard rules for this because one table’s veneer can easily differ from the next one, even if it’s the same make/model. So you might have to cut into veneers with a razor blade to determine exactly what they are made of – if plywood underneath is exposed, this will show you that veneer cannot be sanded or shellacked.

– oak, mahogany, and other red/orange woods are fairly easy to work with since they can usually be sanded smooth after being stripped but some darker hardwoods such as purpleheart may need replacement veneer cut to size for them to come out looking decent.

– veneer will rarely layer evenly on horizontal surfaces because it’s difficult for most to apply it without bubbles appearing here and there due to the thickness of coats so possibly the only way around this is to apply thin layers, waiting for each one to dry then sand lightly between coats.

– edge banding is another option if you don’t mind paying for it – many furniture stores sell pieces with veneer glued directly on plywood edges, so all you have to do is snap them apart then glue them on a new edge.

– if the entire tabletop needs replacement due to being water damaged or just plain old surface, look into getting salvage wood from someplace that specializes in reclaiming lumber – sometimes even floorboards are nailed together which can be separated by heating nails. Also, look into ordering real hardwood flooring (solid wood, not laminate) since it is usually cheaper than most solid wood counters and bar tops, plus most of it is salvaged from old homes/buildings before they were torn down.

– shellac coats will sometimes be “shot” with wood filler before a topcoat of whatever finish is applied.

– after applying the first few coats of shellac, you can lightly sand down/buff in between coats if filled this way. This helps get rid of stray dust particles, which could later cause an un-even sheen.

– spraying lacquer or anything other than shellac underneath veneer might prevent your table from properly adhering to substrate, especially if its old surface plus any primer should be oil-based otherwise it will dry too fast and not properly stick to the substrate.

Everyone’s finish is different, so some experimentation might be required, before finding a specific technique that works best with your setup.  

Some use compressed air while others use a blow dryer – the main thing is to let the finish dry and always work in a room with good airflow since most finishes emit icky chemicals that can make “you” sick if you inhale them.

We hope this article helps you restore that beautiful antique table you own back to life.

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