I am finishing a redwood footboard that I just built. Per the advice of the guys down at Woodcraft, I sealed the board with General Finishes Seal a Cell and am applying three coats of the Urethane and Oil Topcoat (also General Finishes). I used the topcoat on an oak veneer table I refinished last year and I loved the results.
In between coats I am sanding with 600 grit sandpaper. I tried 320 on the table I refinished, but it seemed to pull off too much of the topcoat. The topcoat on the footboard is a wipe on formula, but I am using a foam brush because there are a lot of joined edges that are difficult to get into with a rag. Currently I’ve finished with the second coat and it has completely dried (24 hours). Here’s my question: There appears to be an extremely fine gritty feel over my second coat. It is barely perceptible and most people probably wouldn’t even notice it. I finished the piece in an enclosed room and haven’t been working on other pieces (ie kicking up dust) while finishing this piece so I don’t THINK it is floating sawdust or dirt that has attached itself to the finish. If you run your hand over the piece quickly you can’t hardly tell, but it is definitely there. How can I get rid of this and what caused it? Will the third coat of topcoat do away with it or magnify the problem? I thought I read somewhere on this forum that when applying the last coat of shellac some people just spray or wipe on a thin coat of acetone to slightly dissolve the last layer of shellac for a really smooth finish. Could I do something similar with mineral spirits and the urethane topcoat on this piece or would that kill the finish? I’m a total newbie at most of this, so any advice is greatly appreciated!!
It really feels like I could almost rub it out with a rag because it is so fine and nearly imperceptible, but I’d like to avoid it in the future. This won’t really kill the piece for me so if there is no solution I can live with it, but it will probably drive me crazy for as long as the bed is in my house.
Replies
Jay,
600-grit wet-or-dry (silicon-carbide) abrasive lubricated with mineral spirits or soapy water will knock down the surface irregularities.
-Jazzdogg-
Whether you think you can, or you think you can't, you're right.
There are always microscopic particles floating in the air. They fall off your clothes and hair. Moving in a room will get them active. The key to getting a perfect finish is in polishing the surface after your top coats have completely dried. For some surfaces, a buffing with a fine abrasive like 0000 steel wool or fine sandpaper may be all you want. This is often followed by a coat of paste wax. If you want to take the shine to the next level, finer abrasives such as buffing compounds can be used. You need to make sure your materials are compatible and your technique is correct. I don't expect a perfect finish right off the brush or sprayer. Those are just the methods for applying the coating. The next steps of leveling and polishing make the difference.
Beat it to fit / Paint it to match
I concur with Hammer. I will also add that final rub out of a varnish finish (I assume that's what you meant when you said urethane) should only occur after the finish has completely cured. This is typically a few weeks. The best way to determine if the finish has cured is by smell. If the finish doesn't produce an odor then the finish has cured. If there is still an odor then the finish is still curing.
--Rob
I am applying the finish and then using the same foam brush to wipe it off after waiting a few minutes. When you suggest "wipe it off" how much "off" do you mean? The instructions suggest you use the same wet utensil to wipe and warn against using too much pressure, so really it just becomes a wipe smooth rather than a wipe off. Is that wrong? When you talk about the final rubbing, is there a specific process you follow or do you just put some elbow grease into a clean shop rag and buff the piece? I applied the third coat yesterday and applied a much thinner coat. The piece is much smoother and there are only a few areas that I have noticed some really minor grit (I wouldn't even call it grit - it is just not totally smooth). I think that if I just rub it out after a couple of weeks as suggested it will take care of it. Is there anything else I should do? The color and lustre are perfect really, I just hope I can perfect the texture.
Jay,
The grit could be being produced from bits of the foam brush or from the air due to the fact that the wiping method you are using allows a thicker build and hence a slower drying time. Generally, "apply and wipe off" means to wipe off with a rag removing all but the fine film that has already adhered to the layer underneath it. I know it is counter-intuitive but "wipe on, wipe off" really does work.This is also why many coats are required to get a sufficient build to provide protection. I apply the finish, usually using a rag , and then use a dry rag to lightly wipe the area down. On the initial coats I wait a few minutes and go back over the piece again and very lightly wipe a 2nd time to remove any residue that may have surfaced. A this point everything should be dry to the touch.
On BLO or tung oil without the thinners and varnished mixed in, you would apply and then wipe off in 20 - 30 minutes and then come back a second and sometimes 3rd time to remove the residue. Usually the first coat is thinned to saturate deep into the pores and provide the "bed" for the subsequent coats, The second coat is usually a little thicker and so on. Eventually the wiping-off will yield a fairly level top cost.
I use 0000 steel wool to lightly work in the oil before I wipe it off. A recent post also recommended using 1200 grit wet and dry to very lightly rub in the oil. Either way, you get an extremely smoother finish.
A high-quality wax is recommended for oil finishes since the protective layers are thin and and not as hard as other top coats.
Doug
Doug,
Thanks so much for the insight and help. Wiping off the topcoat entirely does seem somewhat counterintuitive, but I will give it a try. I looked up several articles on finishing and finishes, and they are all very informative, but most just give a categorical rundown of what kind of finishes are made with what oils, how to prepare the finish for application, how to prepare the wood for finishing, what appearance/strength they provide, etc. I haven't found a good article that really provides good insight on how to apply the different finishes and what methods work best with what kinds of finishes (other than a brief mention of the pros and cons of spraying poly).
One more question I have then - when you are applying such a thin layer with each application, what do you do to prevent from sanding through the thin layer between applications or do you skip the "in-between" sanding altogether? Even with my thick application I only used 600 grit sandpaper because I felt the 320 was pulling off so much of the topcoat. I guess this is a process of trial and error that most everyone goes through as they learn how to finish.
Jay,
There is a difference between sanding and using an abrasive material to rub in the oil. Think of the abrasive as the rubbing pad. 12200 or 0000 steel wool used in conjunction with the oil will only remove surface nibs at best. The other role they play is to create a fine slurry that acts as a pore filler. I have not been using oil very long and went through the exact same frustration and got clarification from Jeff Hewett at Homestead and the folks at Highland regarding the application Maloof's rubbing oil.
Doug
I have no idea if I am replying to your "putting it on iwth a foam brush"
But here goes. i have often applied a wipe on varnish (non-poly, for what that is worth). I put it on with a foam brush and then wipe it off. It is a good way to apply this finish, particularly to get into corners. But, yes, you wipe it off, and then do it again. And again.
Gretchen
Gretchen and Doug,
Thanks so much for the advice. This should really help me finish the piece!
You are using a foam brush but are you then wiping it off?
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