Help with flush veneer door slabs

[Doug Herzberg]

I think I have a problem with some custom door slabs. They're solid core (particle board) cherry veneer with natural cherry edges. It looks like the veneer over the cherry edges is going to finish darker than the veneer over the particle board core. The veneer itself appears to be very thin cherry over an mdf core, much like mdf core veneer "plywood" but thinner, maybe 1/8"

My plan was a light sanding with 220, vacuuming, a wipe with mineral spirits, then MW Pre-Stain conditioner, Zar-Plus satin poly with a maple stain, then MW WOP.

This photo is after the wipe with mineral spirits. You can see the dark strip along the right edge. I have tried spot sanding the darker strip at the edge, but it didn't seem to improve it much. At least it didn't make it worse.

This is the inside of a closet door, so I could try finishing all the way to see if the conditioner evens it out or the stain covers it, but I thought I should see if anyone has had this problem first.

Any suggestions?

[Todd Burch]

Looks like almost-sanded-through-veneer. I vote move forward (inside of closet door!!) and be done with it.

[Scott Holmes]

That cherry is about 1/64" thick possibly less... sanding is a bad idea. You said "... satin poly with a maple stain"... not in that order or is the stain in the poly? If it is in the poly then it's technically a toner. Most toners need to be sprayed to get an even color. Most toners are fast drying lacquer or shellac. A slow drying varnish toner is most always problematic...

[Doug Herzberg]

Thanks for your replies. Todd, if it's almost sanded through, it's not because of what I did. The cherry had some lines from light or air exposure during shipping. I only gave it a light pass with 220 to even out the color before finishing. This was recommended by the manufacturer. The spot sanding was after I noticed the dark stripe which runs across the grain.

I first thought it was from the difference in pressure between the particle board and the natural wood when the veneer was pressed, but I could see the sander at the manufacturer leaving a different texture or thinner veneer over the natural wood if it wasn't the exact same thickness as the core. With the mineral spirits dried out, and the afternoon sun shining across the surface, I can see a change in the surface texture where the problem is. I attached a photo, but the sun washed out all the color. The two diagonal lines are the shadow of a blind cord, but you can see the change in the surface at the edge.


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Scott, Zar Plus is an oil based satin poly with stain incorporated. It is recommended by the manufacturer for use on new wood and over old finishes. The instructions are brush on, wipe off, like a stain. I have used it to restore old finishes on this job and tested it on some veneer samples. In the test, it brought the new cherry very close to the old finishes in the door casing, etc. Each coat darkens the color a little, so my plan was to switch to clear poly when I get the color I need. It's two hours between coats. The pre stain conditioner seems to keep the stain from getting into the grain so much, which I think is a better look. The combination I want to use is the second vertical band from the right in the photo of the test piece.

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I didn't have any trouble getting a consistent color on any one piece of veneer. There is a remarkable difference between each strip of veneer, which creates a striped effect on the door, as you can see in the sample. Is that what you mean by not getting a uniform color? I think I want the stripes, but I don't have a lot of experience with this. The veneers run horizontally on the door slabs, the horizontal stripes of the grain are part of the effect I'm after. The stripes from the veneer differences, not so much, but I don't want to hide the grain too much.

[Jim Becker]

Doug, if you want to have any kind of control over color including consistency, please avoid any product that incorporates stain/dye in the finish, itself. Even if it's sprayed (not really the best idea for a slow drying oil based finish), it's very, very hard to get a satisfying result and pretty much impossible if using a brush. (This is where the saying, "PolyShades is the worst thing to ever happen to a can" came from...) IMHO, of course...and you know how much you paid for it.

[Doug Herzberg]

Thanks again for all your help. I'm up to the 2nd coat of ZAR on the test side (inside closet door). Now I'm sanding by feel, more than sight, between coats and I can definitely feel the roll at the edge where the core changes from particle board to solid wood. It's like the solid wood is a hair thinner than the particle board.

Maybe I should have opted for a stave core. I thought the particle board would be more stable, especially since there is a large difference in humidity between the place of manufacture and the place where it will end up.

I appreciate all the advice about the product I'm using, but I think the problem is the wood, not the finish. I'm not married to this ZAR, in fact it's the first time I've used it. I also prefer to stain first, finish later, but I've used the MW integrated products occasionally, usually because I wasn't paying attention when I bought them, and I haven't had problems with consistency of the color. I'm ignoring the brush and using a wipe on, wipe off technique, which gives me a lot of control, IMHO. Spraying isn't an option in this application.

Jim, I paid $18.99 per quart for it. I don't know what you meant by "you know what you paid for it." I bought it from a supplier with a lot of experience in furniture finishing and paid more than I wanted to because I trusted his recommendation. So far the only problem has been with a brush on technique - if it pools in a detail in a molding profile, it creates a dark line, as you would expect from something like this. Kind of an antiqued look, but not what I'm after.

The problem remains the roll in the veneer at the edge. Either the light strikes it at a slightly different angle or the surface of the veneer was altered, perhaps by pressure during glue up or sanding (or lack of it, if it's a dip in the surface). I've written the manufacturer to see if this has been an issue before. Haven't heard back, but yesterday was a holiday most places.

Thanks again for looking.

I just edited to add a couple photos. It looks worse in the picture than in real life, but you can definitely see the dark stripes at the edges. The light area in the foreground is from an overhead light, not any inconsistency in the finish. The second coat of ZAR has only been on about an hour in these photos.

[Jim Becker]

The "you know what you paid for it" refers to my opinion (IMHO = in my humble opinion), not the product you're using... ;)

The effect you're getting in the recesses is just one example of why a finish with color added is so hard to get consistent results from. You can have similar issues at edges if you didn't "break" them with abrasives prior to applying the finish (due to finish pulling away from the edge and piling up) as well as with the difficulty of applying an even thickness of finish with a brush, no matter how experienced one might be. In the case of your molding, you're getting a "glazed" effect...as you state, desirable in some styles, but perhaps not what you were looking for.

Sad you're having the issue with the edges. I'm suspecting it could be something to do with how the veneer adhesive reacted to the solid stock under the edges versus how it laid down on the particle board core.

[Todd Burch]

I was thinking it was more due to the initial bite of an aggressive wide belt sander (deeper scratches) coupled with out of plane inner cores due to the solid edging being thicker.

[Doug Herzberg]

I was thinking it was more due to the initial bite of an aggressive wide belt sander (deeper scratches) coupled with out of plane inner cores due to the solid edging being thicker.

Kind of like snipe on a thickness planer? I didn't use any power tools. Is there such a thing as an 80" sander that a door manufacturer might use?

Have been in contact with my vendor and he is sending photos to the manufacturer for comment. Appreciate all your help.

[Todd Burch]

Yes - my comments were in reference to how the door was manufactured - not how you finished it.

[Doug Herzberg]

The effect you're getting in the recesses is just one example of why a finish with color added is so hard to get consistent results from. You can have similar issues at edges if you didn't "break" them with abrasives prior to applying the finish (due to finish pulling away from the edge and piling up) as well as with the difficulty of applying an even thickness of finish with a brush, no matter how experienced one might be. In the case of your molding, you're getting a "glazed" effect...as you state, desirable in some styles, but perhaps not what you were looking for.


Thanks Jim for the clarification. I understand what you're saying here and agree. I think stain might do the same thing in the recesses. The "glazed" effect you're talking about is exactly what I meant - carelessness on my part caused that. I think it's what Scott was talking about when he called it a toner. If I could spray a toner here like they do in furniture factories, I can imagine a very even color, but to me it would be like painting - the more you sprayed the toner, the less you would see of the wood. I would think that even a light scratch would reveal the original color, whereas a stain might penetrate deep enough to survive at least minor damage.

I have only done the back side of one closet door, so I have 15 sides to go. The vendor has asked me not to do any more until he hears back from the manufacturer, but I can still change products. I'm sure I can get this exact color stain without the poly, stain it, then start in with clear poly. I'm pretty sure this wood is going to darken with age and exposure to light and the poly may yellow it a bit, but I'm hoping it all works out.

That raises another question. None of the polys I bought says anything about UV protection. Haven't ever tried to find that, but perhaps I should.

[Jim Becker]

Unless the polyurethane you are considering is an exterior finish, it's more often than not going to have any UV protection added to it. Since I never use poly, I unfortunately cannot point you to an interior product that does have UV protection.

[Scott Holmes]

I would not be using poly I would use a UV stable phenolic resin varnish like Waterlox or I would use a UV stable waterborne finish. Some the high end WB finishes have UV inhibitors added to interior finishes.

[Doug Herzberg]

I would not be using poly I would use a UV stable phenolic resin varnish like Waterlox or I would use a UV stable waterborne finish. Some the high end WB finishes have UV inhibitors added to interior finishes.

Scott, I've heard the name "Waterlox" but know nothing else about it. I Googled the name and came up with Waterlox Tung Oil floor finish, with different sheens. I like no sanding between coats and the idea of a "penetrating" vs. a "surface" finish.

Some of these doors will be installed in a kitchen ares and will have to be washed over their lives. I see that Waterlox is water resistant. Can it hold up to degreasers? Since I'm on hold, I have time to look into alternative processes.

[Doug Herzberg]

The vendor has not heard back from the manufacturer, but he did speak with his finisher. He's recommending that I start with 180 grit on a random orbit sander, apply stain, inspect and wipe any dark areas with a cloth moistened with mineral spirits to lighten them, then proceed to top coats. I have four more "back sides" of doors to experiment with, so I'm getting ready to give it a try. I think I'll go looking for stain with no poly and look into Waterlox.

Does Waterlox affect the color or darkness of the finish? I have several veneer samples, so I can do a color test before I start on an actual door.

[Doug Herzberg]

I would not be using poly I would use a UV stable phenolic resin varnish like Waterlox or I would use a UV stable waterborne finish. Some the high end WB finishes have UV inhibitors added to interior finishes.

Just spent some time on the Waterlox website. Looks like only their gloss marine finish has UV protection. The local dealer is Woodcraft and they have some good guys working there, so I'll see what they have to say, too.

Thanks to everyone who has chimed in so far.

[Scott Holmes]

Wait Don't use an exterior varnish on an interior project.

Waterlox Orignal is a high quality VARNISH not an oil/varnish blend... It will build a film finish.

My comment on UV stable was that phenolic resin varnishes are UV stable, poly is not! Marine varnish is much softer and will not be as durable as the original Waterlox.

Yes, Waterlox also makes excellent floor finishes but there are not as hard as the original because they have urethane in them.



Waterborne finishes need a UV additive.

[Doug Herzberg]

Thanks, Scott. I've got the ZAR oil based stain without poly in the same labeled color, although it's a little different. Not using the pre-stain conditioner. I'm up to three coats of Waterlox Original Sealer / Finish on the veneer sample and it's looking pretty good. I hope this is the product you were recommending. I'm not planning to use an exterior varnish.

It doesn't seem to have any gloss at all right now. Very natural looking. If I understand the label directions, if I want the satin sheen, I put on the Waterlox satin top coat, which I haven't purchased yet. Given that some of the doors will be in a kitchen and will have to be washed, it seems like a satin finish might be better. Any thoughts on that?

I haven't sanded at all since putting on the stain and I have a little lint in the finish. (I'm on-site and can't get a clean environment). I plan to do a light sanding prior to doing the satin coat, if I decide to use it. Still need to see if the vendor's advice fixes the dark streaks on the doors.

[Scott Holmes]

Waterlox Original Sealer - Finish dries to a a bit less than gloss. It is basically thinned Waterlox Original a.k.a. a wiping varnish. You will need 3 wipe-on coats to get the same build as a brush on coat so until you have 5 or 6 wipe-on coats don't be too concerned about the gloss or the build.


If you give this finish a week or two to cure then hit it with 4/0 steelwool you will have a satin finish.

Lint "in" the finish (I thinking trapped under splinters from wiping the stain) is more of a problem than dust/lint stuck "on" the finish. I would get the lint "in" the finish out ASAP. If it's just dust bunnies.. don't worry, be happy.

Satin and gloss are both well suited for the kitchen.