Techniques for smooth glazing. November 18, 2002
We are now doing our first glaze job, and we are very lost on the correct procedure. We are putting a brown glaze over an off-white paint. We need a light glaze with light streaks on the flat parts. We are currently thinning our glaze with paint thinner and wiping it on with a paint brush to get our desired coverage and brush strokes. Are we even close to getting this right?
From contributor D:
You need to be more specific about the types of finish you are using, but I can give you the general procedure for lacquer finishes. First, primer-surfacer to the desired smoothness. Then base color of lacquer. Next, a light coat of vinyl sealer. Then glaze in a manner that gives you the look you want. Then another light coat of vinyl sealer. Last, one or two topcoats of NC or pre-cat lacquer.
Hints: You can tint your primer to use as your base color, thus eliminating one step. Don't apply glaze too heavy or lifting can occur - if more color is needed, tint the glaze darker. Scuff very carefully to avoid damaging the glaze. Use NC or pre-cats only - no post cats or conversion varnish, as these will lift the glaze easily.
From the original questioner:
We are painting with SW Cab lacquer, then sealing with lacquer, then applying an oil-based glaze, letting dry, then sealing with another coat of Cab lacquer. Our main problem is the customer wants a real light glaze, so we are just streaking the glaze on with a brush to give us some streaking marks, and this takes forever to get to the right consistency. If it is too thin, you come back to a door you have done a few minutes ago and all your streaks have turned into dots as the glaze has puddled up.
You are putting it on too wet. Try a more dry brush technique.
1) Before you put on the glaze you need to sand (scuff thoroughly with ScotchBrite or a sanding sponge) the base coating. It's puddling up due to surface tension caused by the smoothness of the previous film.
2) The above is right about the dry brush approach. For what you're trying to achieve, you don't need or want to put on a ton of glaze. Also, don't thin the glaze. You need something that will hang. Glaze is supposed to be thicker than stain. You need this bulk to get it to stay put.
If you are looking for a light glaze effect, take a natural glaze and tint it a little with 844 or 866 tints - maybe start with a couple ounces of tint to a quart. Using a glaze with less colorant, you can wet the whole door with glaze and work it with cheesecloth or brushes to the desired effect without the frustration of trying to get a heavily pigmented glaze to go on lightly. If you go this route, use only a scotchbrite pad, as sandpaper or sponges may scratch your clearcoat too much and the scratches will show when you glaze.
From contributor D:
I've had success using gel stains as glazes. For some reason they don't seem to have the lifting or recoat window problems associated with linseed oil based glazes like Campbell and Behlen. Zar also works well. Also, they seem to have good workability, and are easier to get a "dark in the grooves" look. Commercial glazes just don't seem to have enough pigment for this without applying them too heavy, which causes lifting and risk of damage when scuff sanding the sealer over the glaze. (I have a feeling that maybe the store that mixes glazes for me is just being stingy on the pigments.) I use the dry brush technique a lot. Use a good quality oil brush, like a Wooster yachtsman, brush on randomly and use another brush to work it out and remove excess glaze.
When using separate colorants to tint long oil alkyd stains, look to use the 824 system for better compatibility and acceptance. I would also advise against using CABs over alkyd base products unless you plan on letting those surfaces dry for at least 24 - 36 hours. Nitrocellulose is the better film former and will help minimize the risk of poor adhesion, which is often the case when using CABs.
Here's the procedure I follow: First, I apply the primer surfacer and then check it to be sure that all the grains are filled up. I then apply the base color, then immediately apply the glaze. I try to make my own glaze from Alkyd paste with a little oil colorants and the slow drying thinner. The slow drying thinner is very important for even application of the glaze by wiping or by dry brushing. I mix no more than 30 of the slow drying thinner to the glaze so that it will dry easily with no bubbles afterwards if you coat it with NC sealer. I never had a problem with this system. After the sealer I do some toning (spraying) of some solvent base stain to make the surface (the colors) more lively, then I finish it with NC topcoat at gloss 40 to give some elegant finish.
With the mahogany wood we have here in the Philippines, I apply first the waterbase stain by spraying then wiping off excess material. After the surface has dried, I seal it with ordinary NC sealer (high solids between (21-31%). After drying, I apply the glaze (the same as above), then I seal it again, then I tone it with the final color (toning stain - solvent base with NC topcoat as binder - if you have ethyl acetate, it is better to use to thin down the toning stain). After five to ten minutes, the surface is now ready for topcoat.
Sounds as if the glaze you are using is mixed way too thin. Try letting it flash a little longer and then strike off the majority with brush and the 4odd wool to desired effect.