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Thread: Confused about a spirit varnish over a sunburst on first mandolin

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    Default Confused about a spirit varnish over a sunburst on first mandolin

    I finished my first scratch build F5 and put a hand rubbed sunburst finish on it using Stew Mac colorTone stains (#5030, #5032, #5034). Mixed them with distilled water. Applied them with satisfactory results. Then attempted to varnish with a 1704 spirit varnish using 190 proof Everclear alcohol. I was under the impression from various things I read, that I could varnish over the sunburst without it dissolving into the water based ColorTone stains. Well...wrong. I googled a lot looked here, but can't seem to find info about how to do this. So, in wanting to get this F5 to a happy end point (since I'm half way through two new F5 builds) I chose to give it a few light coats of StewMac nitrocellulose lacquer. I had fallen in love with the mandolin while it was in the white and didn't want to put off the being able to play it while I sorted out the varnish problem. Any thought on what I did wrong? Thank you so much in advance.

  2. #2
    Registered User Steve Sorensen's Avatar
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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    I have found locking in the color with a sprayed coat of Shellac, followed by a couple of wiped-on coats of Tru-Oil works great to avoid the problem that you are describing.

    Don't think I would want lacquer in the mix unless I was doing a lacquer finish.

    Steve

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    Registered User amowry's Avatar
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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    Yes, a few sprayed coats of shellac (the first very light, then slightly heavier) should lock in the dye so subsequent coats won't disturb it. Once TransTint dries, it's the same stuff whether you initially thinned it with water or alcohol, so the fact that you thinned it with water doesn't affect how likely it is to be disturbed by later finish/sealer coats. Of the finishes and sealers I've used, Tru-Oil is the least likely to to disturb TransTint. Some builders do you use lacquer as a sealer under varnishes, but I think that the more products you introduce to the mix the more likely you are to encounter an issue with adhesion.

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    Adrian Minarovic
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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    I tend to believe that old Gibsons used oil varnish instead of spirit/shellac right over the dye as it disturbed color the least, applied few coats of oil to seal color and create good base and then went to spirit/french polish. Once they found out, in '25 or so, they can spray nitro over the burst they abandoned the old way.
    Adrian

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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    Adrian, same for early teens as for 20's you think?

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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    There has been a lot of conjecture about old Gibson varnish finishes.

    I think most of us will agree that at least the outer coats, at least in 'teens instruments of most colors, were some sort of spirit varnish.

    I have often wondered whether some oil varnish was also sometimes [but not always] used. One thing that makes me guess this is that the Sheraton brown finishes have a "softer" look to me. But that is only a guess.

    Oil varnish dries slowly, therefore slowing down production; so I tend to believe that if a large volume manufacturer like Gibson used it, they only used it sparingly.

    I'm not sure the '20's finishes were necessarily done the same way as the 'teens finishes. And I'm not sure that all 'teens instruments were finished the same way. The techniques may have varied, depending on the colors used.

    I am sure that the colors are aniline dyes. If you have to do finish repair on an old Gibson, you will find that you can get a nearly perfect color match by using the old fashioned powdered violin dyes.

    Lynn Dudenbostel told me that he believed that Pratt & Lambert "38" varnish was about the closest he could get to an early '20's finish. If I remember correctly, he described the Loar period finish as a "very early alkyd based oil varnish." Is this correct? I don't know. Lynn put quite a lot of effort into studying the Loar finishes, and he certainly knows more about it than I do. I know that the "38" varnish was his finish of preference. Unfortunately, Pratt & Lambert discontinued it last year.
    Last edited by rcc56; Apr-02-2020 at 7:27pm.

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  10. #7
    Adrian Minarovic
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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    Bill Halsey studied the finishes on his collection of teens and early 20's Gibsons a nd came to conclusion that they used oil varnish base (judging by typical features of slow drying finishes like runs and sags etc.) and (in his words) generous layer of french polished spirit varnish. The story goes like... when he had a chance to ask old paint store owner (who had shop near the Gibson plant in Kalamazoo back in the days) he put a can of old oil varnish (short oil phenolic resin) on counter from back of the store...
    I don't think finishing with oil is slower than spirit varnish. Such oil varnish in one well (but no too thinly) brushed layer will dry overnight and the thickness of layer is typically equivalent to half dozen layers of typical brushed spirit varnish. If the layer is brushed on by skilled person 3-4 such layers will create almost flawless smooth surface that only needs some scuff sanding to remove any dust nibs or to level small runs (which in some cases were left without leveling). Gibson scraped bindings clean only after the varnish was on and created visible steps at the binding and then applied top layer of spirit varnish that provided the shiny surface (unlike modern instruments which get scraped after thin seal coat and following sprayed finish floods everything level). The most logical choice for a factory setting would be quickly brushing shellac (2-3 layers in 1 hour intervals) on top of scuffed oil varnish and next day you can slightly scuff sand and polish with FP technique without much need for building layers.
    I think that for lower end instruments they just skipped some steps.... fewer layers of oil varnish (perhaps just one generous layer to seal the sheraton brown) and go to few brushed layers of spirit varnish perhaps with just minimal polishing (pumice/ rottenstone).
    Application of nitro was not faster (I can brush one layer of oil varnish in 5 minutes on mandolin and total time from bare wood to strung up can be 10 days or so if everyting goes well) but required less skill and the finish wasn't tacky soon after application and didn't require so much care during drying. When I experimented with speed finishing, with one layer of oil sealer, next day in the morning 5 thinly brushed coats of 2lb cut shellac (30 minutes apart) and gently french polished the same evening. I polished the finish palm of my hand next day (hard hand rub - friction creates heat and smoothes the shellac and especially on top I feel that it helps evaporate the ethanol faster and the finish hardens better to prevent stuck bridges), strung up on day 3 evening and not trace of bridge imprint when I checked few months later (I rub wax into bottom of bridges to help as well).
    Adrian

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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    I still have a jar of rottenstone I got from Vitali's in the early 70's. Ironically to do an oil re-fin on an old Gibson A.

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    Registered User Nick Gellie's Avatar
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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    So Hogo what is in your varnish recipe? So you are using one base varnish coat and six coats of spirit varnish in your finish recipe?

    Quote Originally Posted by HoGo View Post
    Bill Halsey studied the finishes on his collection of teens and early 20's Gibsons and came to conclusion that they used oil varnish base (judging by typical features of slow drying finishes like runs and sags etc.) and (in his words) generous layer of french polished spirit varnish. The story goes like... when he had a chance to ask old paint store owner (who had shop near the Gibson plant in Kalamazoo back in the days) he put a can of old oil varnish (short oil phenolic resin) on counter from back of the store...
    I don't think finishing with oil is slower than spirit varnish. Such oil varnish in one well (but no too thinly) brushed layer will dry overnight and the thickness of layer is typically equivalent to half dozen layers of typical brushed spirit varnish. If the layer is brushed on by skilled person 3-4 such layers will create almost flawless smooth surface that only needs some scuff sanding to remove any dust nibs or to level small runs (which in some cases were left without leveling). Gibson scraped bindings clean only after the varnish was on and created visible steps at the binding and then applied top layer of spirit varnish that provided the shiny surface (unlike modern instruments which get scraped after thin seal coat and following sprayed finish floods everything level). The most logical choice for a factory setting would be quickly brushing shellac (2-3 layers in 1 hour intervals) on top of scuffed oil varnish and next day you can slightly scuff sand and polish with FP technique without much need for building layers.
    I think that for lower end instruments they just skipped some steps.... fewer layers of oil varnish (perhaps just one generous layer to seal the sheraton brown) and go to few brushed layers of spirit varnish perhaps with just minimal polishing (pumice/ rottenstone).
    Application of nitro was not faster (I can brush one layer of oil varnish in 5 minutes on mandolin and total time from bare wood to strung up can be 10 days or so if everyting goes well) but required less skill and the finish wasn't tacky soon after application and didn't require so much care during drying. When I experimented with speed finishing, with one layer of oil sealer, next day in the morning 5 thinly brushed coats of 2lb cut shellac (30 minutes apart) and gently french polished the same evening. I polished the finish palm of my hand next day (hard hand rub - friction creates heat and smoothes the shellac and especially on top I feel that it helps evaporate the ethanol faster and the finish hardens better to prevent stuck bridges), strung up on day 3 evening and not trace of bridge imprint when I checked few months later (I rub wax into bottom of bridges to help as well).
    Nic Gellie

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    Adrian Minarovic
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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    Personally I airbrush almost dry layer of sheallac to seal the color and then brush 3-5 layers of oil varnish (currently this one :https://www.ceneo.pl/8297358 - simiar to old style phenolic varnishes - I found two small 200ml cans of it on our trip to Poland many years ago and took two home just to test it and I just opened the second can two mandolins ago). I use cheap Ikea brushes (the widest one - approx. 1" - from this set I "borrowed" from my kids https://www.ikea.com/sk/sk/p/mala-stetce-6-ks-10193319/ ). I used to use expensive brushes but this one works as good or better once I trimmed very ends of hair so it's all perfectly same length, and it is much easier to clean than natural hair. I scuff sand the surface and brush 2-3 layers of my 2lb cut of shellac (this time with soft natural hair brush). Let it dry for a day and french polish... I usually don't hurry finishing these days and leave it dry for few days between stages.
    This finish ages nicely with fine texture (here is instrument after 10 years of use), similar to vintage mandolins.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Adrian

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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    Thank you Steve, Andrew, and Adrian for sharing your experience. Much appreciated! I'll post photos/clip when I'm done.

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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    Quote Originally Posted by amowry View Post
    Yes, a few sprayed coats of shellac (the first very light, then slightly heavier) should lock in the dye so subsequent coats won't disturb it. Once TransTint dries, it's the same stuff whether you initially thinned it with water or alcohol, so the fact that you thinned it with water doesn't affect how likely it is to be disturbed by later finish/sealer coats. Of the finishes and sealers I've used, Tru-Oil is the least likely to to disturb TransTint. Some builders do you use lacquer as a sealer under varnishes, but I think that the more products you introduce to the mix the more likely you are to encounter an issue with adhesion.
    Andrew,
    Thank you for clarifying that dyes like TransTint can be disturbed by both water and alcohol based sealer coats, regardless of how it is thinned. I had always wondered how thinner selection could determine sealer coat options since TransTint can be diluted with either. I have yet to start my first build, but since this thread popped up I have a few questions for down the road.
    For those of us without spray setups, could something like Zinsser Bulls Eye Shellac in a rattle can work to apply those light sealer coats?
    You mentioned Tru-Oil not disturbing TransTint, are their any limitations for finish options above the Tru-Oil?
    Any reasons to choose Tru-Oil or shellac over the other for sealer coat?


    Thanks,
    Greg

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    Default Re: Confused about a spirit varnish over a sunburst on first mand

    I have used the water based stains on all of my spruce topped guitars [ usually an Amber shade, have not done a SB ] I usually brush on a light coat of shellac and then French Polish as normal. I've never had an issue with the stain bleeding, changing. I suspect that if one were to use an alcohol based stain there "WOULD" be an issue. Why I use water based.

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