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| rubbing out varnish - help http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=6144 |
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| Author: | paul harrell [ Thu Apr 13, 2006 12:17 pm ] |
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I have never liked gloss film finishes ( caution rant ahead: why would anyone want to take beautiful wood, smear eopxy in the pores and cover it with plastic? - okay end of rant). After a lot of experimentation I like varnish better the alternatives but the sides are driving me crazy. The top and back come out fine - I use abralon pads on a RO sander, then some micro-mesh and finish with Novus polishes on a foam pad. But the sides I do over and over and always end up with witness lines in the waist and upper bout. I level sand with 600, then go to 1200 and 2000 and usually have witness lines before I even get to a uniformly dull surface. I have also tried using the abralon pads on a felt block, same problem. When I do the top and back I sand much more aggresively, and have no problem. The sides, no matter how slowly and carefully I go, show witness lines at the waist almost as soon as I start. If anyone can help I would appreciate it - on the eight guitars I have built so far I have more hours in finishing than building in every case. ready to throw something, Paul Harrell |
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| Author: | Don Williams [ Thu Apr 13, 2006 12:19 pm ] |
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So tell me Paul, what varnish are you using? "more hours finishing than building" Yep...that sounds exactly right. |
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| Author: | Colby Horton [ Thu Apr 13, 2006 12:25 pm ] |
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Are you going from 600 to 1200?? If so, that is probably your problem. You should work up slowly in those coarser grits like: 600 to 800 to 1,000 to 1500 to 2000. |
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| Author: | paul harrell [ Thu Apr 13, 2006 12:47 pm ] |
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I'm using Behlens rock hard varnish thinned about 20% with their reducer and a little acetone. I make sure the last coat goes on as soon as the second to last is dry, usually about 4 hours. I've tried starting with 3200 micro mesh and going to 12000 without skipping any grits, same proplem. Usually after redoing the sides three or four times I get them to an acceptable finish, but I just tried to rub out my third attempt on the sides of my latest build and........ If I don't figure it out soon I'm afraid the guitar may meet the wall of my shop. Paul |
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| Author: | Robbie O'Brien [ Fri Apr 14, 2006 12:56 am ] |
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Paul, I feel your pain! No, really I do! You are putting on coats of varnish so thin that when sanding you are going through the coats and thus the witness lines. One thing I might suggest is to hand sand these problem areas. It is much less agressive then the RO sander. Also, French polish hides witness lines very well. |
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| Author: | Skip Beach [ Fri Apr 14, 2006 2:26 am ] |
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Hi Paul, This worked for me ... After final sanding & leveling, try wiping on two further thinned coats very carefully - 50% turpentine to 50% varnish. With it being this thin & by using the oily turpentine as thinner, it should stay wet longer & self-level nicely. Then walk away & leave it to dry hard - a week at least. Then hand polish with the two finest Novus polishes being careful not to polish through those final thin coats. Looks good & avoids witness lines. Good Luck!! Skip |
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| Author: | John How [ Fri Apr 14, 2006 3:13 am ] |
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Paul, this is how I mix my rockhard varnish, In approximately 8 ounces of varnish I add 2 capfulls of rockhard reducer and 1 capfull of acetone. The acetone helps greatly with the bite into the previous layer which helps reduce witness lines. Also carefully level prior to your final coat and don't be too agresive with your final sanding. I have been spraying my varnish lately which also reduces the amount of finish sanding before buffing. Also when you are buffing assuming you are using a wheel, use pretty light pressure so you don't buff thru. It takes some practice but it is a good finish. |
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| Author: | Howard Klepper [ Fri Apr 14, 2006 4:53 am ] |
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[QUOTE=paul harrell] I have never liked gloss film finishes ( caution rant ahead: why would anyone want to take beautiful wood, smear eopxy in the pores and cover it with plastic? - okay end of rant). [/QUOTE] Well, If you don't like gloss film finishes, why are you rubbing out the varnish? As the the why of filling pores with epoxy and covering with plastic (varnish is plastic, too), it's for a few reasons. It seals the wood and protects it from splashes and sweat. It looks pretty to many people's eyes. And (drumroll) it's impossible otherwise to get people to exchange money for them. |
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| Author: | CarltonM [ Fri Apr 14, 2006 6:16 am ] |
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[QUOTE=Howard Klepper]Well, If you don't like gloss film finishes, why are you rubbing out the varnish?[/QUOTE] Too shiney as applied? Short varnishes (of which Rockhard is one) are naturally quite shiney. |
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| Author: | paul harrell [ Fri Apr 14, 2006 7:14 am ] |
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Yes I know varnish is shiny, but as was pointed out no one will buy a guitar without a gloss finish ( maybe I should move to England where other finishes are tolerated). Robie, I am hand sanding the sides. I only use the RO sander on the back and top. I don't think I'm putting a thinner coat on the sides, but maybe I am. I just can't figure out why I can sand and polish the top and back pretty agressively and then go through the top coat on the sides when being very careful, using much less pressure. John, I am using acetone too but it doesn't seem to help with the witness lines. What grit do you use to level sand the last coat before buffing? I dont't have a buffing wheel, so I use the foam pads from SM with the Novus polishes. I also level sand the second to last coat to try and minimize final sanding. Skip, I think I'll try your suggestion to fix the sides on my current build. Thanks to everyone for the replies, Paul Harrrell |
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| Author: | RussellR [ Fri Apr 14, 2006 7:38 am ] |
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Is the US Market really that against Satin Finishes ? I know Lowden export, and as far as I'm aware theirs would be Satin, unless they do a special finish for the uS Market, and I just sold one with an oil finish to the USA, I think Dave has sold at least one to the US too. |
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| Author: | Phil Marino [ Fri Apr 14, 2006 7:46 am ] |
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[QUOTE=Skip Beach] Hi Paul, This worked for me ... After final sanding & leveling, try wiping on two further thinned coats very carefully - 50% turpentine to 50% varnish. With it being this thin & by using the oily turpentine as thinner, it should stay wet longer & self-level nicely. Then walk away & leave it to dry hard - a week at least. Then hand polish with the two finest Novus polishes being careful not to polish through those final thin coats. Looks good & avoids witness lines. Good Luck!! Skip [/QUOTE] Skip - Is the idea behind using two thinned coats ( rather than one) that you won't get a witness line between them if you just rub through the first one ? Do you apply the second thin coat soon enough to "meld" with the first? Or, do they meld together better just because of the extra thinner? Thanks, Phil |
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| Author: | MSpencer [ Fri Apr 14, 2006 3:16 pm ] |
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RussellR, I am one of those guys that is not all that crazy about the plastic high gloss look. I am not a professional like many of these folks that know better what the market wants than I do for sure. What I like for me might not sell. Mike |
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| Author: | Skip Beach [ Fri Apr 14, 2006 5:24 pm ] |
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Hi Phil, The reason I used two thinned coats (within 3 hours for better adhesion) was because these coats are so thin that if you level sand with 600 grit or rougher wet/dry paper, it may take two coats to get the finish perfectly filled in, smooth & shiney again. One thinned coat did not dry really shiney after 600 grit wet/dry leveling ... so I wiped on a second one. Then, hopefully, later you won't polish so hard as to rub through those thin coat(s). Skip |
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| Author: | Alan Carruth [ Sat Apr 15, 2006 7:54 am ] |
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One other additive that you could try: a very small amount of kerosene (or, if you prefer, oil of spike lavender). A few drops per pint of mix will help you to brush it out more level, and avoid some of the need for sanding. That's the real 'trick' IMO: getting the last few coats level enough that you don't have to sand through to get the surface right. This, in turn, relies on good surface prep. Allowing the varnish to sit for a week or more after the last coat went on may help the hardness to equalize. OTOH, you end up with more shrinkage before doing your polishing, so you're more likely to go through the thinner coats and get witness lines. Sigh. I wonder what it would take to get them to re-introduce the old '4-Hour Rubbing Varnish'? Gad that was wonderful stuff.... |
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