Ok, I’m not much of a varnisher. Shellac is my finish of choice, being easy to pad on, even for someone as ham-fisted as I can be. But the trestle dining table I just finished for a friend called for a hard, varnished surface. So I went with the Behlen’s Rock-Hard.
I hand planed the tabletop first, then sanded to 220. Because of the hand planing, the surface was not absolutely flat. I rubbed in some linseed oil, then gave it 2 coats of blonde dewaxed shellac, then brushed on three coats of varnish, using a good quality brush. The first coat was thinned 50%, the second coat was 75% varnish, and the third coat was full strength. I let each coat dry 24 hours.
After the third coat, I noticed 3 or 4 spots that I had missed, so I touched them up 12 hours later. I think that this was my big mistake. After letting the tabletop cure for 4 days, I rubbed it out with 600 grit sandpaper on a palm sander (I am after a matte finish), then 0000 steel wool. The lines showed up, badly, around the spots where I did the touch ups.
So, my question is this: How do I proceed? Should I try to add another coat or two, of 75% varnish? (I would like to avoid using it full strength, not having the utmost faith in my own brushing technique.) Or do I sand it all of and start again?
The first of the two photos below shows the problem.
Thanks for your input.
Alex
Replies
Langhorne Clemens . . .
. . . it was Langhorne Clemens.
Loose the palm sander for fixing little finish areas at least. Just hand sand with abrasive paper around a block of felt ( see tool supplies for felt block ). 600 may be a bit too fine until all the problem is level and nearly gone.
>Not flat BECAUSE of the hand planing. <
Surely you meant IN SPITE OF hand planing.
Thin is good; keep going with the thinned stuff.
Oh and you haven't a prayer unless you use an Apple laptop. ( everybody knows that ). Something about the psychic mental state it puts the operator in; or is it the color spectrum generated by the screen. Well something like that any way. I just know it is true.
: )
PS: you are going to hate this . . . to get the best final look you are going to have to sand the entire surface with the same final grit around a soft pad to blend the problem areas into the rest. Where ever you don't sand at all is going to say look at me. Most people won't ever notice; just your woodworker pals and you.
As to the planing - the pieces went through the planer, then the whole tabletop was flattened with a #5 jack after glue-up. There was a (very) gentle dip or two remaining, but not worth fighting about..
The palm sander I'm using is a Speed Bloc, which has a pretty good felt pad. I will take your advice, though, and get a felt block and do it by hand.
"Thin is good; keep going with the thinned stuff." The main words I am taking from this are "keep going". As opposed to 'sand it off and start again. Right? Will the witness lines disappear with succesive coats?
That's not me or my computer in the pic... but I find those "think different" people annoying. (I hope I didn't just put my size 14 in my mouth.)
BTW: Google agrees with me about Groucho. (Never the Twain shall meet, if ya wanna get literary...)
Alex
Samuel
But isn't it more fun to say "Langhorne" ?
Strippers (no, not that kind)
I posted the same question on The Burl, and a coupla guys recommended using a chemical stripper to take off everything and then start anew. To me this sounded wrong - like it would leave a residue, or a bleached look, or spottiness. They said that it would be much easier and more effective than trying to sand the topcoat off.
I will try to apply another coat first (the less drastic solution), but if it doesn't work, what is your opinion of stripping vs. sanding?
Alex
Nothing wrong with using stripper--it is vastly preferred if you want to remove all finish. Does less damage to patina and leaves surface more able to accept dye or stain. Only it shouldn't be needed to eliminate witness lines. Usually they completely disappear when the next coat is applied. Just be sure that the surface is smooth, even if that means a few more witness lines.
I am the one
who replied on the burl that perhaps he should strip it. that was after I suggested that the varnish could be cut back and recoatted.. i just think that there may be another underlying problem there -perhaps contamination. I see where there was a computer used ofter sanding and see where the shiny areas are where ever something contacted the surface.
first coat was blo. no problem there but did he wipe it dry and the 2 coats of white shellac and then varnish. the 2 coats of shellac don't accomplish anything as the blo and varnish are compatable with one another. icould see orange shellac if perhps he wanted to warm the colour a bit. my alternative is that if there is a problem and due to inexperience it is sometimes easier to start over than to keep piling on to try and rescue something.
ron
The computer was only put on the tabletop after the varnish had cured for 4 days.
The problem was probably a combination of my brushing technique, and the fact that the conditions where I applied the varnish were less than ideal. I curtained off a section of my shop (my cramped basement) with 2 mil plastic dropcloths.But there was not much room to move around in my little tent, and the lighting was less than ideal.
Moving forward, I will first rub it out with some 400 grit on a felt bock, then apply another coat of varnish, maybe 85% strength, and see what happens.
This won't happen for a few weeks. I will repost when I try the fix.
Thanks for the advice.
Alex
280 or 320 will be fine
to cut the finish back with. don't go through the shellac.
what colour are you getting on the sandpaper now. white-powdery or yellow and clumping?
ron
White powdery
Avoiding witness lines during rub out
Ok, so here is the follow-up:
I brushed on another coat of varnish (75% varnish, 25% thinner; the can said that was ok) the other day, and the witness lines disappeared. So far, so good.
Now my question is this: How do I rub the glossy finish of the Behlen's Rock hard down to a matte, without causing the same problem to arise again? Is pumice and linseed oil on a felt block the way to go?
I worry a little, because the surface of the varnish is not perfectly flat. Looking at the table top with a low-angle light source, I can see the undulations from hand-planing. I am afraid that when I start to rub, these irregularities will be the source of more lines.
It will be a couple of weeks before I attack again, so the varnish will have plenty of time to cure.
Thanks for your sugestions.
Alex
Nix the felt block--use felt but a more flexible piece and a flat finger tips. On this final rub it is OK to use the pumice with paraffin oil or rubbing compound to follow the undilation. Thinning the final coat as little as possible, to get a good full coat is also desirable. The label doesn't know what you have in mind. Depending on the varnish, you probably would get the brush strokes to flow out nicely by thinning more on the order of 10% give or take.
Thanks for the reply.
Well, the coat is already on, thinned 25%. I will try to rub that out with felt, pumice, and mineral oil. If I get lines again, I will try another coat, with less thinner.
Alex
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