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Anyone have any idea how thick a "typical" wiping varnish goes on per application?

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sweat the small stuff.

It depends on the varnish and whether / by how much it is thinned. What varnish are you using?

Charlie, I've been BRUSHING KTM-SV and having nothing but trouble. Here's a recent thread on the subject: http://luthiersforum.com/forum/viewtopic.php?f=10101&t=37492&hilit=Bubbles

Just for the hell of it, I tried wiping some coats thinned about 25% with water. It certainly went on smoother and there weren't any bubbles. I'm just afraid I'm going to have to apply 40 coats to get a good build. Not to mention I really don't know what I'm doing. At this point, I've sanded completely back to wood and am starting from scatch. I'd rather not have to do that again. Any thoughts?

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sweat the small stuff.

Don't know if you've seen this already, but below is a link to an old thread over at the kit forum that talks about wiping P&L varnish. It might be of some help. I haven't used any varnish on a guitar yet, but plan to and have done some experimenting on scrap. I liked the results I got using the method described in the linked thread. I also got some great info / advice from another member here (George L) who used the same method with success. You might ping him and see if he can answer any specific questions.

http://www.kitguitarsforum.com/archives ... 91_0_7_0_C

I have been brushing on water based varnish on my mandolins for many years, and also used the same varnish on two guitars. Have been using Target Coatings EM2000 and it's predecessors. I tried KTM SV, but went back to EM2000. The main reason was the KTM SV is a lot more difficult to apply by brush, even when thinned with water. EM2000 has undergone a process of development over the years, and earlier formulations had problems with bubbles and one batch I got was really difficult to apply with a brush if you did not get the thinning with water spot on. The latest formulation has solved all the problems as far as I can tell, and you can wipe, brush or spray it on. Water based finishes require a particular technique with the brush. I use a high quality artificial artist brush, and thin it 20% with water. Brush it on as smoothly as you can, but don't fiddle with it. Let it dry and deal with imperfections afterwards. EM2000 chemically is similar to KTM SV, and when cured I could not tell any difference in resistance to scratching and denting. There is a marketing premium put on varnish finishes with mandolins so I have persisted despite the problems, but now get excellent results with EM2000.

I haven't actually tried it yet, but for my build I was planning on following this method:
http://www.liutaiomottola.com/PrevPubs/ ... arnish.htm
Has anyone else tried this - does it work?

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"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Very thin and the thickness will vary depending on which type of wiping varnish you use and your application process. Wiping varnish is a thinned penetrating finish and wont build as well as a film finish will such as shellac or lacquer. I tested the thickness of a wiping varnish finish recently...I applied 8 coats of Liberon Finishing oil (wipe on wipe off technique) and did not see any measurable build in thickness using my .001" calipers. Also the pores were just barely beginning to fill in at this point.

I have also tried Formby's Tung Oil using the Read/Motolla technique (http://liutaiomottola.com/PrevPubs/Wipi ... arnish.htm) where the varnish is wiped on and allowed to dry without wiping off. This technique allows the finish to build like a true varnish and it builds noticeably thicker than the wipe on wipe off technique. The finish looks excellent but it's not nearly as durable as a true brush on varnish.

Peter, funny I just posted with this link. I just finished a bouzouki using this technique. The finish looked great and it built up very well but it was not durable at all just a few days after I finished the schedule. Perhaps I should have waited longer for the finish to cure but I don't think even when fully cured this finish will be as durable as a true varnish or laquer. Especially on soft woods like cedar, it seems like there is no finish on at all and the lightest touch would scratch it. The natural oils in the rosewood gave me problems as I didnt think to wipe with Naptha before applying the first few coats. I am reluctant to use this finish or any other wiping varnish finish on rosewoods. If you do be sure to wipe with Naptha until all the oils are out of the wood and then apply the finish as soon as the Naptha dries.

It's been a few months since I finished my bouzouki so I will check if the finish has cured any harder. If you use this technique I recommend letting the instrument hang after the last coat of finish and don't touch it for 2 weeks-1 month+ before continuing.

Here are a few pics. You can sort of get an idea of the sheen and build...

I'm finishing up a guitar using Arm-R-Seal (essentially a wiping varnish, but with some urethane), wiping it on using blue shop rags. It has taken a lot of application/sanding cycles, but the hog pores are filled and I think I have the application process down. I'm getting much more consistent, especially after thinning the arm-r-seal with mineral spirits. I really like the process, feel, look and color. Ambers the hog beautifully, but does not like the ebony headplate. Poly worked much better on that. I like the naptha idea, should cure that particular problem.

Gentlemen, thank you so much for the various responses. I have a tremendous amount to learn about finishing and a lot of it I'm learning the hard way. It sounds like there are no hard fast rules and becoming experienced with a particular finish is key. I'm quite interested in EM2000, perhaps I'll give that a try the next go 'round. I was about ready to go back to brushing KTM-9, but I think I'll give wiping a try with the KTM-SV. Sanding this guitar down to wood was quite revealing to me as to how thick the finish was going on with the brush. Way thicker than I thought. Not good. I should have some results to report back by this weekend. Wish me luck! A lot of good information in the articles mentioned in this thread, by the way. Quite helpful. Thank you again.

Heath

_________________
sweat the small stuff.

Goodin, I like the look of that finish. It's a shame about the durability though. Do you think thinning it less would let it build up more and provide more protection? My build is mahogany so compatibility shouldn't be a problem. Did you use a pore filler? If you put on a coat of epoxy it might harden the surface, but then the varnish might not be compatible.

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Peter - I think if you thinned it would only make for more coats to build up the finish to the desired sheen. Thinning is probably not necessary for pre-mixed wiping varnishes like Liberon, Formbys Tung Oil, etc. unless it starts to thicken when you get near the bottom of the can. I don't think thinning has any effect on how the varnish will cure but I could be wrong. The more coats applied the more durable and higher sheen.

Wiping varnish works beautifully on mahogany. I didn't use any pore filler but you could if you want. I like the natural un-pore-filled look when using a wiping varnish when applied in a few coats built to a satin sheen using the wipe on wipe off method. Pore filling would probably look best using the wipe on/leave on technique built to many coats and a high sheen.

I think using epoxy as a base coat would defeat the purpose of wiping varnish. Wiping varnish is a penetrating oil finish (well sometimes no oil, it can be confusing). The finish penetrates into the wood and brings out depth and color. Applying wiping varnish over any other finish would not allow it to penetrate I would think, but I haven't tried it. Also you may have adhesion issues if applied over some finishes. I have heard people applying a thin base coat of shellac over spruce tops to keep the finish from penetrating and supposedly dampening the tone. I personally think finish penetration has no adverse effect on tone. I know a professional builder in Europe who uses exclusively oil wiping varnish finishes on his acoustics and they sound wonderful.

Here are a few pics of a cocobolo dulcimer I did awhile back using about 8-10 coats of Liberon, wipe on/wipe off and not pore filled. It turned out great with a nice satin almost semi gloss sheen. It took months to cure due to the oils of the coco (forgot to Naptha off the coco oils before applying first few coats).

Edit: Just read that second link which answers my question!

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

"Wiping varnish is a penetrating oil finish (well sometimes no oil, it can be confusing)."

Another confusing thing in this discussion is that some people are talking about using wiping as a technique to apply "regular" varnish, which is ordinarily sprayed or brushed on, while others are talking about using finishes that are designed to be applied with a rag. These latter "wiping varnisheds" (for example, Tru-Oil) are often called "oil finishes" but are thinned varnish, more or less.

I've been following this discussion with interest, because I'd like to use(regular) varnish, but I'm hoping for an easier if slower way to apply it. Thinning varnish and applying it with a rag or paper towel is said to be less dependent on technique and equipment than brushing or spraying.

If your using a varnish designed to be used like a penetrating oil finish, filling pores with epoxy and/or sealing with shellac would not give you the "in the wood" look associated with this kind of finish. But if you're using a regular varnish, such as the Pratt and Lambert gloss varnish discussed in one of the links, then filling and sealing would be appropriate.

I have a couple varnishes and appropriate thinners: guess I have to get started on some experiments . . .

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Tim Allen
"Never hurry, never rest."

Well said Tim. Let us know how you experiments turn out.