Sealing Maple Plywood Before Staining

A beginner asks for advice on a hand-applied seal coat for maple plywood to allow even staining with a brushed top coat. March 25, 2007

I'm at the finishing stage of an 18 cabinet kitchen project. I'm using a wiped on/brushed on system for the stain and clear coats. I've chosen a 50/50 mix of Bartley gel stains as the color. My problem is with the yellowing effect of the conditioner I'm using before the stain. My client does not like the yellow tint that I'm achieving in my test pieces. I'm currently using Olympic wood conditioner. I suspect it is a linseed oil based product, but that is a guess.

Can anyone suggest some out of the box products available to seal the maple ply and maple hardwoods for even stain application? I want to keep the solution as simple as possible with products available at local retail sources. Iím a small one man (sometimes 1.5 man) startup company and I donít have the contacts and resources like the older, more experienced shops. I've searched this site and the Zinsser Bulls Eye clear shellac (bleached shellac) sounds interesting. I've read that the Zinsser product contains was which may need to be removed by freezing. Also Bartley makes a varnish, which they claim will act as a pre-treat conditioner for stain.

All suggestions, even the complicated ones, are welcome, although Iím looking for a simple product recommendation for a non-yellowing pre-stain sealer for maple ply and hardwood. I'm about 8 man-hours away from a standstill.

Forum Responses
(Finishing Forum)
From contributor T:
One of the advantages of gel stain is that it usually does not blotch like a penetrating stain would. In other words, you probably don't need a pre-conditioner. Try a sample without it and see what happens. (I'm assuming you've selected a non-yellowing finish coat.)

If you still want to pre-seal and you have a non-yellowing topcoat, thin it down probably 1:1 (10% solids) and give your project a light coat. Follow that with your stain and top coat full strength. If for any reason you can't thin your topcoat that much, get some Deft, thin it 1:1 and use that to seal your project.

Anything with a varnish is likely to be yellow: some more, some less. If you don't want yellow, don't use it as either a sealer or a finish. You'll need a pre- or post-cat lacquer or a non-yellowing WB finish.

From contributor J:
With solvent based stains, you can use Glue-siz to condition before staining. This product is water clear. Only way to get this product in small amounts is Custom Pak Adhesives.

From the original questioner:
Yes, I am using a clear topcoat. Yes, I chose the gel stain for its anti-blotching properties. I am trying to seal the plywood primarily, as that is soaking up the stain more readily than my hard maple face frames. I have tried the stain on ply without conditioner and I prefer to use the conditioner as the grain ends (pores) seem to be less prominent when using the sealer. I'm using polycrylic as the topcoat, brushed on with good results.

From contributor C:
Contributor T is right that you may be best off without any conditioner. If you want to use one, though, the Zinsser Seal Coat is dewaxed and fine to use right out of the can... negligible yellowing effect, too. You can thin it with alcohol if needed but I have found that just a very light application is usually fine right from the can. You can try samples both ways and see what works best. The spray cans are handy for sample making.

From contributor T:
Don't know your stain color, but polyacrylic can get an amber cast on very light stains even though it claims to be crystal clear. Glue size will work fine. You can make your own by thinning PVA (white wood glue) down with water. Up to 10 parts water to one part glue. I usually do 4 or 5 to1. Let dry, sand and stain.

Seal coat works well too but does have a slight amber color. You can use it full strength or thin up to 1:1 with ethanol. Let dry, sand and stain. You can thin your polyacrylic down and brush on a thin coat or you could even apply it full strength. Sand with 180 or 220, stain and finish.

There are plenty of options but those three are probably the simplest. They will seal the open pores and lock the wood grain it place prior to staining and they are not yellow.

From contributor R:
A simple yet effective and frugal way around this is to first wipe the plywood down with paint thinner, not real sopping wet, but wet enough to cover the plywood. Hit it with a dry rag so you don't have any puddles or real wet areas. Now go ahead and use your gelled stain. If you haven't made any samples yet, now would be a good time to start.

From contributor J:
You don't say what you're using for a finish coat. I use spray-on vinyl sealer and pre-cat lacquer. You might be able to do what I do (using your finish). I seal, sand, and apply one coat of finish, sand with 320 grit paper, and then apply gel stain. Let it dry thoroughly, and then apply the rest of your finish coats.

I've never had a problem with this, and I get no blotching, just a nice, even stain. Remember, the maple will naturally yellow with age, even if you use a finish with UV inhibitors.

From the original questioner:
Thanks. The end grain of the maple hardwood door stiles, cross-cut on the router, seem to really be soaking up the stain unattractively. I definitely hope to seal up some of this soaking effect. The plywood isnít as problematic but I do hope to even out the stain by using a conditioner. Iíll try these ideas on some samples in addition to the dozens of samples Iíve already created.

1. White wood glue and water to one part glue.
2. Zinsser Seal Coat.
3. Paint thinner. Thought about this already, but not using it on the plywood; rather, the hardwood face frames, as those arenít taking the stain as heavily as the plywood. I hoped that using thinner or alcohol on the hardwood would open up the pores somewhat and make it accept more stain to match the plywood better. Iíll probably end up doing an extra coat or two of stain on the face frames to match the ply, which is fine with me.

From contributor C:
Your plan sounds pretty good, but instead of doing an extra coat of stain, you should use some of it to make a toner for the frames. Basically, you just mix some of the stain into your clear coat and spray it on. This way you get assured adhesion and more positive control. You can also darken individual boards this way if needed.

From contributor M:
A little about the white glue sizing. For your close grained woods, use 1/3 white glue to 2/3 of clean water. On the open grained woods, use 50% white glue to 50% clean water. These measurements are not critical, but I use them for consistency in my finishing. Keep the glue sizing thoroughly mixed during the entire application.

What do you need to know about glue sizing? You can wipe or brush on the glue sizing, but you must be extra careful that you completely cover the entire surface without missing any spot. In fact, after the first coat is completely dry, I then apply a second coat to be sure that I covered the entire surface completely with the glue sizing, and then allow enough time for drying. My reason for mentioning the two coats of sizing, and completely covering the entire surface, is that if you do not cover it all and there are any missed spots, when you start spraying, the solvents in your coating will get under the missed sizing and wrinkle the glue size and the coating and will ruin the entire finish. This is just a word of caution, as I have been there and done that.

From contributor R:
Since you plan on brushing on your coatings, I can't see you doing any toning. Gelled stains themselves have a pretty decent amount of oils in them to begin with, so err on the side of caution when using products that contain oil.

You can also control the way the wood accepts the stain by adjusting your sanding process. In other words, if the plywood is coming out too light, sand it with a coarser grit paper. The scratch pattern will be wider with a coarser paper, so therefore the color will be darker. If the color is too dark in the end grain routings, just wipe those areas with a rag dipped in paint thinner.

For a more aggressive color removal, use a Scotch Brite pad dipped in paint thinner. Since you're brushing on your coatings, make sure to allow extra drying times for each of your finishing steps. If you use any kind of glue size, allow for extra dry times.

From contributor I:
Sand the end grain only to 320. Your stain should match everything else and not be blotchy.

From contributor W:
Simple solution - just prep the wood, stain seal, lacquer. You can even use the lacquer for your sealer. It will save you money and it's one less step you'll have to do. Using sealer to seal up is cool too, but I feel it's just one unnecessary task and waste of money. Pre-catalyzed lacquer works great for both sealing and finish coat and saves you time, but as far as staining goes, it doesn't get any simper than just those 3 steps.

From contributor R:
Since he plans to brush on his clear finish coats, which brand of lacquer would you suggest he use?

From the original questioner:
Thanks for all your help so far. Lacquer is out due to the fumes. I'm in the process of testing. The thinner solution is okay but not the end all solution. I have some glue sized pieces ready for stain at the moment. I did pick a color; I'm just trying to get the ply to match the hardwood at this point.

From contributor M:
You're going to find out that whenever you stain on wood that is sealed, be it with a sanding or vinyl sealer, wash coats of shellac, preservative sealer, or glue sizing, in most cases you will find you're going to have to darken your stain or glaze. This is normal as you will find when working your samples. In some cases, depending on the color you want, it may be fine; if it is, you lucked out.

From the original questioner:
I ended up glue sizing the face frames with decent results. The seal-all product sealed too much, even when cut with alcohol. The paint thinner didn't seal the pores enough. Thanks to all who helped. Much appreciated.