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Discussion Starter · #1 · (Edited)
Here is an oak plywood cabinet I finished using General's water based products. Can someone explain what these craters and fine streaks (running horizontally below the crater) are, and why they have appeared? Thanks!
 

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Did you use a water based stain also? For whatever reason the finish didn't adhere in the grain. The white is air under the finish. If you used an oil based stain and a water based topcoat I would say that is the reason. It takes a lot of drying time before you can put a water based topcoat over the linseed oil in the stain, usually three days. The bad is regardless of what caused it the finish will need to be stripped before you will can fix it.
 

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Discussion Starter · #5 ·
Did you use a water based stain also? For whatever reason the finish didn't adhere in the grain. The white is air under the finish. If you used an oil based stain and a water based topcoat I would say that is the reason. It takes a lot of drying time before you can put a water based topcoat over the linseed oil in the stain, usually three days. The bad is regardless of what caused it the finish will need to be stripped before you will can fix it.
The white you're seeing is just a light I put over it to highlight the crater. The sheen is perfectly even. The finish did not blush, and even though it wasn't necessary, the stain had two days to dry before I top coated it. Regardless, I did not mix oil with water. It is a water based dye under a water based stain with a water based top coat, all from the same manufacturer.
 

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Ok I think I get it now. This is the complaint. There is often knots in the substrate veneers in today's plywood. I've had a lot of problems with purebond plywood having actual knot holes under the finish layer of veneer. I've had 1/4" plywood you could hold up to sun and have light shine through the plywood. You might tap on the spot with your finger nail and see if it sounds hollow. If it is a solid knot under the veneer you can apply several layers of finish on the spot and make the surface more level.
 

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Do you use any aerosol sprays, (lubricants, etc.) containing silicon in your shop? What you have looks like fisheye, caused by the silicon preventing the finish from flowing out. Once in the air,the stuff can hang around your shop for months. One solution is to use fisheye preventer (available at automotive paint stores). I would give Jeff Jewett at Homestead Finishing a call.
 

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Discussion Starter · #8 ·
Do you use any aerosol sprays, (lubricants, etc.) containing silicon in your shop? What you have looks like fisheye, caused by the silicon preventing the finish from flowing out. Once in the air,the stuff can hang around your shop for months. One solution is to use fisheye preventer (available at automotive paint stores). I would give Jeff Jewett at Homestead Finishing a call.
Never touched an aerosol can of silicon... It sucks cause I'm really shooting for that pro look finish, and then I run into this. It's a never ending learning experience...
 

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Discussion Starter · #9 ·
Ok I think I get it now. This is the complaint. There is often knots in the substrate veneers in today's plywood. I've had a lot of problems with purebond plywood having actual knot holes under the finish layer of veneer. I've had 1/4" plywood you could hold up to sun and have light shine through the plywood. You might tap on the spot with your finger nail and see if it sounds hollow. If it is a solid knot under the veneer you can apply several layers of finish on the spot and make the surface more level.
I don't see how I can layer up one spot without hitting the surrounding areas. I think I'll just have to live with it. I'm not experienced enough to mess with this without trashing it completely. Thanks for highlighting the problem spot! I should have done that in the first place.
 

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I agree with those about the flaw being from a knot or void in the layer right below the veneer. What might not show up before finish will be more obvious when the veneer is wet (from the first coat of finish) it'll try to swell and the only place it can go is into the void below. Finish dries and it can't shrink back to level.
 

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I think that Steve Neul is on the right track.
What woodworkers refer to as "wood pores" are the tall chains of vessel elements, the water conduction wood cell type in broadleaf/angiosperm tree species.

1. All of the species in the red oak group (Quercus rubra and others) have open vessels in bands which I see running sort of left to right on your surface veneer.
2. I'll go so far as to guess that you did not use a paste sealer (and sand back) to fill the open voids of the vessels.
3. Next, you used a water-based stain.
4. That has soaked right through the surface veneer vessel bands and hydrated the core veneer, causing it to swell and deform the surface. Those veneers got the bejeezlies squished out of them in the thermosetting glue-up when the plywood was made, cooled and sanded.
Since there's stain chemicals in there as well, I doubt that the core veneers will ever settle down again.
 

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I don't see how I can layer up one spot without hitting the surrounding areas. I think I'll just have to live with it. I'm not experienced enough to mess with this without trashing it completely. Thanks for highlighting the problem spot! I should have done that in the first place.
Looks like to me you sprayed that face flat and just put down too much. You can't let it puddle or pool. Waterbase polyurethane works best done in thin applications. I would just use 320x and sand it flat, and re-coat.






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Discussion Starter · #14 ·
Looks like to me you sprayed that face flat and just put down too much. You can't let it puddle or pool. Waterbase polyurethane works best done in thin applications. I would just use 320x and sand it flat, and re-coat.






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Nope, sprayed it on vertically. If there is one thing I can pat myself on the back for it's having the feel of putting on a wet enough coat that it is not too light and not too heavy that it will run. I have put 5 coats on there with sanding (320 grit) in between.
 

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Discussion Starter · #15 ·
I think that Steve Neul is on the right track.
What woodworkers refer to as "wood pores" are the tall chains of vessel elements, the water conduction wood cell type in broadleaf/angiosperm tree species.

1. All of the species in the red oak group (Quercus rubra and others) have open vessels in bands which I see running sort of left to right on your surface veneer.
2. I'll go so far as to guess that you did not use a paste sealer (and sand back) to fill the open voids of the vessels.
3. Next, you used a water-based stain.
4. That has soaked right through the surface veneer vessel bands and hydrated the core veneer, causing it to swell and deform the surface. Those veneers got the bejeezlies squished out of them in the thermosetting glue-up when the plywood was made, cooled and sanded.
Since there's stain chemicals in there as well, I doubt that the core veneers will ever settle down again.
I think you nailed it. Regardless of this issue, I have gotten sick of red oak and it's coarse grain.
 

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I don't see how I can layer up one spot without hitting the surrounding areas. I think I'll just have to live with it. I'm not experienced enough to mess with this without trashing it completely. Thanks for highlighting the problem spot! I should have done that in the first place.
It's not as difficult as you think. You could just take a sheet of paper and cut a hole roughly the size as the knot and lay it over the door while you are spraying the spot. There should be air between the paper and the door even if you have to put dowels or something between. I don't use that finish so I couldn't speculate on how many coats. When you think you have enough build put an additional coat on the area without the paper. Then take a small block of wood and some 220 grit sandpaper and sand the area. Don't sand too long or you will sand through the finish in the surrounding area. If it needs more sanding then spray the area again without the paper before sanding it again. When you get it level or close enough scuff sand the entire face and put another coat over the entire door.

The whole process isn't that much work but time consuming as the thicker you get the finish the more drying time you need to give it between coats.
 

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I finally found the picture. This is what I'm running into with purebond plywood. The job was painted but it was done with maple plywood. The image to the left was what it looked like when I started applying primer. The veneer wrinkled up because it was hollow behind it. The image to the right is the same spot with the outer veneer shaved off. It was just a knot hole they veneered over. Fortunitely since it was painted I could just bondo the void and paint over it.
 

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While GB is right on with the cabinet scrapers, matching up the boogered finish is a no-brainer = it won't happen.
What reinforces my proposal is that it is plain to see the the next lower core veneer runs at 90 degrees to the surface. Kinda, sorta looks like typical ply assembly.

Perhaps some assurance would come if you have ever seen a plywood press in operation. North Central Plywood in Prince George, BC, operated the biggest press outside of Japan. They could assemble and crush 145 sheets of 3/4" plywood in one squeeze. Sides cut, ends cut, surfaces planed, graded.
What amazed me was the difference between the surface veneer thickness (1/4") and what came out of the sander = 1/16"????

That's where sm424 got into trouble = the vessel bands were like open holes to the core underneath.
 

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While voids can be a problem, core veneers for Red Oak aren't usually Red Oak, and are oriented with face grain towards the face veneer. There wouldn't be a malady due to vessels as they wouldn't be oriented that way.

If a stain or topcoat is applied and penetrates through the face veneers and into the core veneers, it's likely been done too heavy. As a subjective observation, under normal veneer staining and finishing when applied in proper proportions, if sanded through the color coat, you could still be in the face veneer or the very surface of core veneer, as it will be light...no stain.

From the look of the sample door, the finish looks mottled.






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