I am in the process of re-finishing a Red Oak dining table top for a customer and I am getting "pin holes" in the surface of the open grain areas on the final top coats. I have done many of these with no issues and fantastic results. This one is not going well at all. Here is what I have done so far.
1st Attempt: Took the table apart, ran the panels through the sander, finish sanded to 180, raised the grain with a wet sponge, let dry, applied 2 coats of rtm stain, applied 1 coat of enduro sanding sealer, sanded, applied 3 coats of satin enduro CV. The first coat looked weird, looked like little craters in the surface while still wet. As it dried the craters closed up into tiny little pin holes. Called GF and he said solvent pop, I was not waiting long enough between coats, give it 2 hours instead of one, ok, did a final coat the next morning, looks like sh**. Called GF again, he said give a few days it will shrink down. ok. waiting, waiting, looks the same, can't take it any more. Sanded it all off and try again.
2nd attempt: Sanded all back to bare wood. applied 1 coat stain, lightly sanded raised grain, apply 2nd coat of stain, lightly sand, (with advice from GF) apply one coat of GF Armrseal, sand, apply one coat of sanding sealer, sand, apply cv, let dry 3 hours between coats, better but still looks like sh** with tiny little holes in it.
Tried again on a leaf except with just enduro clear poly, better, but still little holes in it. The little holes are only noticeable in the light, but you can feel them, you can feel the grain too real good. It is like the wood is the problem. I did a Walnut top earlier in the week, same steps as above, fantastic results. Did a veneered oak top a couple weeks ago and looks great. At this point I am thinking of sanding it all back down and using a solvent base finish. I always have trouble with water base finishes on oak. Maple, Cherry, Walnut turn out great.
And yes the cv and catalyst was mixed with a power mixer for 5 minutes and sweated in for 30 minutes.
Can you put a retarder in the finish. I'm a solvent guy, so I don't know.
If you can use the retarder and spray very thin coats. Oak is problematic and pinholes go with the wood.
Light coats will help with the pinholes. They are usually caused by the deep grain and the inability of the finish to bridge the grain. When you put a thick coating on it, it can't bridge and it'll form pockets that the finish can't bridge.
You could try a barrier coat of 'De-waxed' shellac and see how that goes.....it may change the color depending upon the grade and color the shellac flakes. Got to make samples. If you don't have flakes, try Zinsser 'Sealcoat' which costs as little as 13.00 per quart. Worth a try.
I also use GF but not their CV yet. I don't do Red Oak but I think it goes with the territory with WB. Mahagony can bridge like that with multiple coats it's just the nature of WB on those species.
They only recommend 5% thinning of CV but you can add their retarder/extender or just do lighter coats. Also it will tighten up somewhat. I've gone back on jobs and the finish looked way tighter than when it left the shop.
Also I gotta say your schedule looks like over kill to me. I'll never understand the raising the grain thing. I've never done it in over 15yrs of finishing for $$$. You're doing multiple sands anyway. I don't get the Armrseal either it's an oil based product? Why add complexity to the process? The CV or Poly would be fine for a table top. I've done multiple desks, countertops and tabletops and have used the pre-cat in the past and now the poly. If it were my project I'd stick to the poly and call it a day. You can thin it how you like and no catalizing. Unless you're putting glass over it every finish scratches including glass.
Looks like a grain filler is needed. I have found that there is a grain filler called Timbermate, needs to go on before staining. And a product called Crystalac, a water based clear filler that can go on after the finish, then just top coat it. I am going to leave it the way it is and use the Crystalac. I will post pics of it if it works and let you know. I also ordered the timbermate I will try on the next oak top and see which I like better. I am new to grain fillers so this will be interesting to see how it turns out.
I wouldn't have thought a grain filler is the remedy here. I have this issue when shooting CV over oak sometimes. I just come at it with a few mist coats to start with, then just carry on with thinner finish than usual, just going slower and thinner basically. If it's just the odd time it occurs that's workable, if I were seeing this all day long i'd be looking at a clear dewaxed shellac sealer initally or similar.
Thanks for all the info folks. After re sanding 2 times, and using a grain filler, still saw a few pin holes coming through. 5 coats of oil based poly urethane on top of a grain filler and still had a few pin holes. There must be something in the wood? The wood will not close up. It looks pretty good now. I did other pieces of oak from my lumber and had no problems as I went. Just on this funky wood. Another woodworker friend suggested that the wood may have been dead when harvested, after sanding the wood did look very white like sap wood?? Would have been better off to re make the top from new wood I think.
in my 30 plus years as a finisher ,when water born was going to be the next big thing all my reps,gave me gallons as samples to try and I DID,THE TRUTH IS THAT THEY REALLY DID NOT IMPROVE THEM TOO MUCH.......From your pic, I see that your application is too heavy on your topcoat,water has a high amount of surface tension therefore the product dose `nt bridge gaps very well unless you flood it on and hope for the best and still looks like crap.Oak and waterborn just suck together.Here is your solution first a coat of vinyl sealer Sherwin Williams is the best,when fully cured give One coat at a time of your waterborn topcoat mixed with a small amount of BUTYL CELLOSOLVE will help the product flow out.Let each coat cure before application of next and if you do a more thorough sanding between coats the finish wont be as lumpy and you will have a good looking open pore finish .flat smooth and nice and crisp grain definition....Let me know how you make out.
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