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I was getting ready to do a whole guitar with Tru oil. I like the results I've gotten on all hardwood instruments in the past, but I did a test piece on Spruce and it seems like it was just not enough protection. I could easily make a mark in it with my fingernail. It was only 4 or 5 coats.

Do you think I would get more protection with something like wipe-on poly? And what's your schedule? I bought the Minwax clear Satin.

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Pat

Wipe-on poly is a pretty common (and standard) finish in the furniture making world. I would suggest taking a piece of test spruce, apply a common approach and see what you think about the hardness relative to a spruce top? Wipe-on poly is hard to screw up. 0000 steel wool between coats can help knock back any streaking. Personally (on furniture) I like to lay it on with a foam brush and then chase it with a cotton rag (cut t-shirt).

Andy

Years ago, I used Lee Valley gel wipe on poly for cabinetry. Wiped it on with a lint free cloth, and rubbed the final coat with 0000 steel wool lubricated with mineral oil. Ended up with with a sheen that was a bit more shiny than satin.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

You can make polyurethane a wiping finish by thinning it with naphtha (or mineral spirits). If kept to the same finish thickness as truoil I think it will offer similar protection.

A spruce finish you can't dent with a fingernail is massively thick.

You are talking 90's-00's Asian Ovation guitars finishes... These super thick finishes aren't exactly known for their contribution to tone....

What I mean is that with the TRU oil, you can mark the spruce almost like there's nothing on it. Even the thinnest of nitro finishes would offer way more protection than that.

So I'm wondering if something like a wipe-on poly would offer more protection than the TRU oil. I've got a test in progress...

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Pat

With only 4 or 5 coats, there's almost no thickness. How long did you let it dry before testing it? TruOil takes at least 6 weeks to get close to final hardness. I believe TruOil will be better protection than the wipeon poly, but that's an uneducated guess.

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

Only a few days. I didn't know that Tru oil needed to cure for full strength.

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Pat

I only have used Tru-Oil on my barnwood electric guitars where I purposely did not want a high gloss, but I have still applied about 20 very thin coats, two per day and let them cure for 30 days or more before giving it a final buff. I have also not applied it over any kind of pore filler or any stains. No experience at all with poly - will be interested in the results of your test.

If your tru-oil is getting old. switch it to a glass container add some vmp naptha and stir, this will keep a while longer. I prefer shellac fp for my tops .Can/t prove it it sounds better to me . If you want a thicker finish thinned pratt and lambert makes an excellent cabinetmakers varnish which will also build a thicker finish sooner than poly .Three coats should do it .You can thin with turpentine for slower finishing or faster in winter with naptha

I/m using min wax satin poly to finish 4 radius dishes and forms I use a foam brush from the dollar store . I sealed the mdf/ply with 2 thin coats of shellac and now putting on 4 coats of poly. If I were to use a brush for an oil based finish ,I have 2 brushes 1 thin 1in and the other 2.5in from kremer pigments in NYC they sell high quality varnish brushes for artists vln makers etc, I sand with 220 after the 2 coats of shellac and will sand the poly with 220 after every 2 nd coat .I prefer vy thin coats of finish. Hope this helps . I would use this same regimen for my ukes, except FP for the top and pore fill with ca.

If I did 20 coats and waited 30 days, I think I would just go with something more traditional like Nitro. I'm looking for an alternative, faster method that just gives enough protection to the spruce that I would feel comfortable sending it out the door.

So far the TRU oil and wipe on poly seem to be about the same toughness, neither of which I feel is enough protection for spruce although they haven't had any time to cure if that makes any difference.

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Pat

Pat,
FWIW, I have finished all my guitars with one type of "varnish" or another, including Tru-Oil. They have all hardened over time, but I don't know that they provide equal protection to nitro. (Frankly, I wouldn't really know how to check.) None of them have been conducive to "fast" application.

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George :-)

I've done both Tru Oil and Minwax wipe on satin poly. Tru Oil, normally 15 coats, Minwax, 7 or 8. With both I use a 3 coats then level, wipe on the last 2 or 3 coats as thin and smooth as possible. The wipe on poly is about twice as tough as the Tru Oil, which still isn't much protection for spruce or cedar but will survive normal use (not pick rash).

You want good protection in a fast to apply finish, Endurovar satin is the way to go. Follow the directions on the can and brush (or spray) on three coats and you're done. The learning curve isn't any more difficult than any other finish and the stuff is tough as nails.

Which is exactly why I went back to lacquer on everything that I build. Four barncasters is enough, the finish is fine but is a royal pain to put on, sand, and try to get the gloss I want. Tru-Oil doesn't fill any imperfections (it seems to highlight them). I also know that when I tried to buff one with only a few days of cure the finish was simply too soft lso now I hang them up for a month. I absolutely would not put it on spruce and send it out the door.

My reaction to Tru-Oil is that it is an acceptable finish for someone who can't spray, is not looking for the highest gloss and probably won't do more than a few instruments in their lifetime. I know folks like it on necks - I'm happy with both solvent and waterborn lacquer and knocking the gloss off with steel wool or scotch brite.

I know that there are lots of great finish materials out there, I just don't have the time and patience (not to mention risking a guitar to something new)