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How soon, upon average, can you recoat a brushed on varnish? By which I mean adding the next coat...

...depends on the varnish...

... and the weather...
at least for some of us. If it takes longer than 24 hours, something may be wrong.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

I've not used a brush, but I've wiped on Tru-Oil, Pratt & Lambert and Ace Hardware varnishes and never had a problem doing one coat per day. I do this indoors, in a back room of my house, so the temp and humidity are pretty stable. Tru-Oil seems to be the slowest of those three to dry.

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George :-)

With the old Behlen Rockhard one coat a day always worked best for me, assuming 70 deg and ~45% RH.

Anyone else wondering what varnish to use now that Rockhard has been discontinued and replaced with some sort of alien impostor?

Oh.
How very....slow....
Thanks though.

Yep, a coat a day is a good rule of thumb.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I do a coat (Of Ace Interior Varnish) every 36-48 hours. Mostly because it's such a drag to scuff sand it, I need a day between!

I'd like to try it after 24 hours, though...

"Anyone else wondering what varnish to use now that Rockhard has been discontinued and replaced with some sort of alien impostor?"

I've finally got going on my finish trials. Just to be a sport, I'm trying the replacement polyurethane 'Rockhard' varnish, a Sherwin-Williams 'Wood Classics' interior varnish, Pratt & Lambert's #38, and something a student picked up, Murdoch's 'Uralkyd-500 Floor Finish', from Sutherland Welles Ltd. So far, I don't like the look of the Behlen's, and the S-W is too soft. THe P&L varnish seems to be about as close to the old Rockhard as anything. The Murdoch's is the most interesting, though.

For one thing, it's the clearest, and almost water white. Sometimes the amber color of the Rockhard was nice, and sometimes you don't want that. With a clear finish you can add color in if you want. It goe son very thin, and you have to watch it when brushing it on to avoid sags and runs. It dries pretty well: less than 24 hours on macassar ebony with no help: the Rockhard always took longer on that, and needed UV. The Murdoch's is also the hardest of the ones I've tried: almost as hard as lacquer, but not chippy so far as I can tell. We're trying it out now on a student's archtop, where the light color looks really good on the maple and spruce. I need to seehow it doe for 'witness lines', and also whether it tends to react with perspiration.

Oh yeah; they thin it with a citrus based solvent; smells neat!

Speaking of 'green' some folks have been trying out 'PolyWhey' water based finish, that's made over in Vermont from the waste materials that Cabot Cheese used to trow out. I may give that a try as well; bad experiences in the past with water based finishes leave me skeptical, but it's interesting.

Highly probable that PolyWhey will be too soft for guitars.
The new KTM mind you...

Thanks for the response, and the research as well. That's very helpful. I had been considering P&L #38 or Epifanes.

The name would seem to indicate that Murdoch's is a urethane/alkyd blend. 2 part urethanes can look great, but spraying is out for me for now. One part urethane tends to have that milky plasticky look, though I know there are exceptions. Sounds like this could be one of them.




Yeah, that's how it is. A hundred years ago or more varnish was the deluxe finish; FP was the quick and dirty one.

Oh man, you guys that think that varnishing one coat per day is too slow, or that sanding the varnish on one guitar is too much work just don't varnish enough! Try sanding the interior of a wooden canoe, takes me hours to sand one coat, and I need to put on four. Varnishing guitars is luxury in comparison.

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Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

I've tried the Murdoch's Uralkyd 500 after reading this thread. viewtopic.php?f=10101&t=39085&hilit=Sutherland and found that it flows and levels really well brushed on, dries slowly 8 - 10 hours between coats, and is very clear and hard. It's hard for me as a novice finisher to keep it from running/sagging on the sides as the dry time is so long so I baled out on finishing the whole guitar, but I think it would make a great guitar finish. Still figure on at least 8 hours between coats, and from what I'm reading that seems pretty quick for most varnishes..

I've got a redwood top that I'm trying it on as a wipe on but it's too hard to control over large areas - worked great on a test piece but it's easy to over work it and end up with a splotchy look. There's probably a technique I'm missing.

I'm now using their Polymerized Tung oil over the 500 to see if that's easier to get an even finish. That's supposed to be a 24 hour dry time but it was much longer on my test piece - 2 days at least for the first coat - but once it dried subsequent coats took more like the recommended 24 hours. I really like the look of the Tung oil for the redwood top but the jury's still out as I'm only partially complete. Hope that helps.

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Thank You and Best To All