While writing this I realized that most of this applies to any spray equipment and that these are not techniques that I use on valuable antique pieces. When restoring antiques it’s best to restore the old finish using that same finishing techniques originally used, with some later factory pieces these ideas could be used.
This candle stand is a reproduction of a country made stand that I restored for a customer several months ago. I made the copy out of what I had in the shop at the time. The top is white pine, the turned column is aspen and the three legs are cherry. The finish was done totally with aerosol cans and wax using the techniques discussed below. All the spraying was done on one day and it was rubbed out and waxed the next day, it was rubbed and waxed again several weeks later.
Using aerosol can finishes is not idiot proof, it is a skill, there are things you need to learn and practice to get a good finish. I taught my self to use spray equipment and aerosol cans, I am also always in a hurry, much of what I do is not necessarily correct or conventional. I am always trying to get it done faster without sacrificing the final quality. I rarely spend more than a few hours finishing a piece spread over one day. This is what I do for a living, the more I get done the more I make. I don’t know if anybody else does what I do and I’m not recommending that you do, this is just what I do with new work or where appropriate.
1. Aerosol cans are not adjustable, you can control the film build up by adjusting the distance between the can and the surface to be sprayed and the speed at which you move the can. This is an area that will benefit from practice.
2. #1 above is only partly true you can get different size tips for spray cans the different tips release varying amount of finish. Having spare tips also allows you to use a new tip for each session if necessary.
3. For lacquers and shellac there are 2 types of spray coats that are useful. The first is what I call a spit coat. This is when you hold the can further away from the surface than normal and move it faster than normal. When you do this you get small droplets of finish that hit the surface and almost dry on contact, it leaves an almost but not quite pebbly surface. When using a spit coat with gloss finish you will get a slightly semigloss finish. There are 2 uses for this technique which I will cover below. The second type of coat is what I call a full wet coat, this is when the can is held at the normal distance and moved at the normal speed to get a continuous smooth wet coat of finish on the surface. Too close or too slow and you get runs and sags too far away or too fast you get a spit coat.
4. Runs are not the end of the world, let them dry, carefully scrape them level with a single edge razor blade and one more coat of finish and you are good to go.
5. Back to spit coats, the first use of spit coats is to build a finish on vertical surfaces quickly. By spit coating vertical surfaces you can very quickly build a film without runs or sags, you can apply several spit coats one after another in one session because they are dry almost on contact. Using this technique when spraying a chair I will start spraying the inside of the legs and undercarriage then move to the back, sides and front, by the time I’m done with the front I can go right back to the undercarriage and spray a second coat and so on. Because lacquer and shellac burn in to the previous coats, after you have built the film with spit coats you can level and smooth the surface with one or two full wet coats which will also bring up the gloss. I almost never sand between coats unless I screw up the finish and need to repair it, most screw ups can be repaired with a razor blade and another coat.
The second way I use spit coating is when I want to re-coat an old finish. Many times when you spray a full wet coat of shellac or lacquer on top of an old finish it will cause the old finish to alligator or distort in some way. Because, when spit coating much of the thinner in the finish evaporates before it hits the surface, you are applying a dryer finish and it does not effect the old finish as much if at all. Once the old finish is sealed using spit coats you can spray as normal. This technique needs to be used with great caution or you will be stripping the piece and starting over.
6. Build your film with gloss finish, if you want a semigloss finish, apply one or two coat of semigloss at the end. This I believe yields a deeper richer looking finish than a finish built up totally with semigloss.
7. I use lacquer toners in aerosol cans, there are at least 40 colors available. There are two kind of toners, dye toners and pigment toners. Dye toners are more transparent but they will fade over time. Pigment toners are more opaque and light fast, they don’t fade as much or at all. When spraying toners I will slowly build the colors with spit coats and then seal and level with a full wet coat of finish. I also use a technique similar to dodging and burning in photography. If I want to color a small area of a surface with toner but not the surrounding area, I will make a stencil the shape of the area to be sprayed, by holding the stencil above the surface and moving it while you spray, the edges of the sprayed area will be feathered and blend into the surrounding area. This would be similar to burning in photography. Dodging is also possible.
8. I use a commercial glazes, in aerosol cans, that are compatible with lacquer and shellac and are ready to spray over in less than 30 minutes. You just spray it on, wait until it flashes [ the thinner evaporates enough that it no longer looks shinny on the surface ] then wipe it back to the desired look and finally spray a coat of finish on to seal it in.
9. If you spray shellac or lacquer in high humidity you can have the finish get white patches or turn completely white in severe cases. This is called blushing and is caused by moisture being trapped in the finish as it dries. The solution is to re-liquify the finish and let it dry slower so the moisture escapes. There is a product called blush retarder, in aerosol cans, that does exactly that. I use a lot of it in the summer.
6. As I said earlier I don’t usually sand between coats of finish because shellac and lacquer amalgamate into one layer of film, each coat burns into the previous coats. To complete the finish and get rid of dust nibs, I rub out the finish with wax and steel wool. Besides smoothing out the finish the wax does several other things, it makes the surface slippery this reduces the chance of scratches, it adds to the water resistance of the finish even if only slightly, it makes the surface feel and look richer, and most importantly, because the wax gets in to the low areas of the piece [ corners, along moldings, carvings] when you buff the waxed surface, the high areas take on a gloss and the low areas remain dull this to me looks better than all glossy. I use a colored wax that matches the wood of the project.
If I want a super smooth high gloss finish on a piece, I will seal, tone, glaze, and seal again then build a high gloss finish by french polishing.
Here you can see how toners can be used to make pine, aspen and cherry work together.
In this close up you can see how the wax kills the gloss in the low areas of the turning.