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Thread: Epoxy pore fill and sunburst

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    Default Epoxy pore fill and sunburst

    Hi everyone, I'm working on my 3rd mando and it will have mahogany back ,side and neck. I want to pore fill with epoxy and also dye or sunburst it. My thoughts are to fill pores first and sand back to wood and then dye it.
    How do you approach this? Any advice would be helpful, thanks. Mike

  2. #2

    Default Re: Epoxy pore fill and sunburst

    Cured epoxy is very unlikely to take up dye in any great quantity, and certainly not at the same rate as the wood. I've worked with epoxy a lot on boats, but I'm not sure it would be my first choice as a grain filler. Is this a common application for the material I haven't come across? You could certainly spray paints on an epoxy surface, but I really can't see dye as an option.

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    Default Re: Epoxy pore fill and sunburst

    Hi Mikey,
    In the electric guitar building world, some people do use epoxy for grain fill, specifically a product called Z-poxy which is thinner than traditional epoxy. It's thin enough you can squeegee it. It still takes two applications to get a good pore fill but it doesn't shrink back like other fillers.

    Yes you can sand back to wood and the epoxy left in the pores won't absorb dye, so plan accordingly. You can dye the epoxy dark which would also aid in guiding your sandback, knowing when you've sanded enough. You may be sanding off a little more material in this process, so you may want to leave the back about 0.010" (.25mm) thicker to start if you're carefully tuning the back. You should be able to dye or sunburst the exposed mahogany. The finer you sand, the smoother your transitions can be blended. I have had better luck with dyes that can be applied in an alcohol medium than water based for blending hand-rubbed sunbursts. Of course, if you're spraying the burst, none of those factors will matter as much. Good luck and post pictures!

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    Default Re: Epoxy pore fill and sunburst

    Quote Originally Posted by JimCh View Post
    Cured epoxy is very unlikely to take up dye in any great quantity, and certainly not at the same rate as the wood. I've worked with epoxy a lot on boats, but I'm not sure it would be my first choice as a grain filler. Is this a common application for the material I haven't come across? You could certainly spray paints on an epoxy surface, but I really can't see dye as an option.
    Jim, thanks and sure epoxy won't take up dye, and that's why I want to sand back to wood, hoping not to disturb the pores already filled. I have used epoxy on guitars and it is by far the best pore filler I have used(on mahogany and rosewood), but I've never had to stain or dye the woods on them.

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    gary nava; luthier GarY Nava's Avatar
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    Default Re: Epoxy pore fill and sunburst

    I did a video on grain fillings with epoxy recently, if you're interested.

    Cheers Gary

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    Default Re: Epoxy pore fill and sunburst

    perhaps you could add powdered dye to the epoxy?
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    Default Re: Epoxy pore fill and sunburst

    Quote Originally Posted by GarY Nava View Post
    I did a video on grain fillings with epoxy recently, if you're interested.

    Cheers Gary
    Thanks Gary, my question was more to do with using epoxy and wood dye, so you appear to have sanded back to the bare wood in the video. Would you feel confident applying wood dye after sanding and achieve an even colour?
    I have used epoxy to do exactly what you do in the video and my technique is pretty much the same. The only difference is that I use Bob Smith Industries 20min Finish Epoxy, and use a credit card to apply it. I notice you seem to be using a piece of cardboard, do you find that works better than a credit card?
    Mike

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    gary nava; luthier GarY Nava's Avatar
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    Default Re: Epoxy pore fill and sunburst

    Quote Originally Posted by mikeyb2 View Post
    Thanks Gary, my question was more to do with using epoxy and wood dye, so you appear to have sanded back to the bare wood in the video. Would you feel confident applying wood dye after sanding and achieve an even colour?
    I have used epoxy to do exactly what you do in the video and my technique is pretty much the same. The only difference is that I use Bob Smith Industries 20min Finish Epoxy, and use a credit card to apply it. I notice you seem to be using a piece of cardboard, do you find that works better than a credit card?
    Mike
    I don't think I would be confident applying dye- I don't think you could be 100% sure of no epoxy residue. I just thought the card is more flexible on the carved back plus less libel to mark the wood.
    Cheers Gary

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    Default Re: Epoxy pore fill and sunburst

    Thanks again Gary, looks like I've got some experimenting to do. Cheers Mike.

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    Default Re: Epoxy pore fill and sunburst

    Epoxy pore fill is very common in the guitar world, and I have used it on guitars, but it usually does not involve staining the wood. If colour is added then is it usually added to the finish. Epoxy pore fill followed by sanding and staining would involve a lot of sanding, and I would not be confident the staining would not be patchy. It would depend on what epoxy product was used and how much it penetrates into the wood. Even staining first and then epoxy fill and sanding flat would be tricky because you would probably sand through the epoxy in places and remove stain. I have never used epoxy with stains or dyes. Practice on scrap until you get it right.
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    Default Re: Epoxy pore fill and sunburst

    I am currently working on an all mahogany L-00 type guitar for a friend. My friend wants a 1930s style dye tobacco sunburst finish. I plan to create the sunburst on the guitar body with Trans Tint water dyes, followed by clear epoxy grain filling, followed by a top coat of General Finishes water based Endurovar.

    For grain filling, I am using System 3 Silver Tip laminating epoxy with the fast hardener. Several excellent guitar makers including John Greven and Jay Lichty, use the silver tip (or similar) epoxy for grain filling. Their preferred method is to fill the pores and leave a thin layer of epoxy on the surface of the guitar as it “warms” the water based topcoat. However, I’ve never seen a description of this method of pore filling over a stained body.

    As Peter pointed out, without careful sanding, it’s possible to cut through the epoxy and into the stain. I’m currently working on perfecting my technique using several mahogany scraps. So far, I haven’t accidentally cut through the epoxy. It seems to leave a fairly manageable surface that’s a bit harder to cut through than a typical lacquer or varnish topcoat. I scraped most of the epoxy flat with a razor blade prior to flattening and clean up with 400 grit. I turned the razor blade into a mini scraper by turning the edge on the side of a screwdriver.

    I’m still working out the details, but it seems to be a plausible method. In contrast, I don’t think that grain filling followed by staining will work as well unless you are going for a dramatic contrast between the grain and the other stained areas.

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    Default Re: Epoxy pore fill and sunburst

    I just finished my first build and used Z-poxy as a grain filler on Steve Smith's recommendation. I also used a card (a used Home Depot gift-card) to scrape the Z-poxy over the instrument in a very very thin layer and sanded it back. In some spots I sanded back to bare wood in others I left a hint of the Z-poxy. Over that I did a couple of coats of spray shellac, oil varnish and Tru oil. I did all clear coat and left it natural, but I know Z-proxy can be tinted.

    I would think the best plan would be to do all your staining FIRST and then any grain filling. I would recommend the z-poxy as it was very easy to use!
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    Default Re: Epoxy pore fill and sunburst

    Bpatrick. That is pretty much the same as what I am trying to achieve and using the same kind of dyes. I'm waiting for my epoxy to arrive and when it does I'll experiment both ways, dye before epoxy and vice versa. Thanks.

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    Default Re: Epoxy pore fill and sunburst

    Another possibility: Mikey- you haven't mention what you're topcoat will be or how you are applying it. If you have a spray rig, then your least risky approach would be to spray the sunburst. Especially if you want to go all the want to the dark opaque tobacco brown around the edges. The epoxy would get you to a totally flat surface first, so you don't have as much leveling of finish to deal with. If you're using nitro, lay down a base coat first so your burst can burn in. With a decent gun and some practice on mando shaped cardboard or plywood, you should be able to get the effect you want. You can then topcoat with lot's of layers of clear before beginning any sanding.

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    Default Re: Epoxy pore fill and sunburst

    Quote Originally Posted by Rob Roy View Post
    Another possibility: Mikey- you haven't mention what you're topcoat will be or how you are applying it. If you have a spray rig, then your least risky approach would be to spray the sunburst. Especially if you want to go all the want to the dark opaque tobacco brown around the edges. The epoxy would get you to a totally flat surface first, so you don't have as much leveling of finish to deal with. If you're using nitro, lay down a base coat first so your burst can burn in. With a decent gun and some practice on mando shaped cardboard or plywood, you should be able to get the effect you want. You can then topcoat with lot's of layers of clear before beginning any sanding.
    Thanks Rob Roy, I don't have spray equipment although will be using spraycan nitro satin and intend to use the Stewmac dyes I already have which will be handrubbed and touched up with an airbrush. This worked for me on my first 2 builds. Thanks for your input though. Mike

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    Default Re: Epoxy pore fill and sunburst

    Are you absolutely determined that you are going to use epoxy? There are other solutions to this problem. Other ways to effectively fill the grain. I've used epoxy to fill grain on guitars, but only because I didn't want to use a colored filler. If I was going to dye it, I wouldn't use epoxy.

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    Default Re: Epoxy pore fill and sunburst

    Here's some photos of my mahogany soundboard samples in progress. They aren't quite finished yet, but you can see the process in action.
    First step, water based Trans Tint dyes on the mahogany (My lovely wife helped) followed with a black airbrushed spray around the edges.

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    Second, 3-4 coats of System 3 Silver Tip laminating epoxy. I also add a bit of System 3 Silica Thickener to the mix. I use a small scale to ensure that the mix ratios are exact. I drop some epoxy onto the surface and use a small vinyl squeegee to cover the area. Scraping and sanding (400 grit) between coats. Final scrape/sand leaves a thin layer of epoxy over the entire surface.

    Click image for larger version. 

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    I'm experimenting with spraying vs. brushing or a combination thereof using General Finishes Eduro-var topcoat. I have lightly sanded between coats to remove nibs and slightly flatten. Going for around 8 coats. The samples on the left are finished (more of less). The sample on the left is covered with not-yet-flattened epoxy. There is some rub through on the edges of the samples. I was aware of these areas and was not as concerned about them while finishing these samples. The epoxy and topcoats like to accumulate at the edges, so more care is needed in these areas. I sanded with 600 between coats and flattened and polished the final surface starting with 800 and then going through to 2000, micro mesh 3600-20,000 followed by #2 and #9 Meguiar's polish.

    Click image for larger version. 

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    Finally, a photo of two larger samples with 4 top coats of Endur-var. I'm going to keep spraying and see how these finish up.

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    This technique seems to be working for me. I have used Z-Poxy in the past and encountered some adhesion problems. I sanded the Z-poxy back to wood and let it only fill the grain. This was a non-stained guitar. So no additional problems of staining to overcome. The EM-6000 finish bubbled up in the Z-Poxy grain filled areas where the player handled the guitar. I have seen several other comments on the internet with the same problems. My problems may have been due to old Z-poxy, incorrect mixture, didn't wait long enough to dry, amine bloom...? Many builders use, and have no problems with Z-Poxy, but I'm shying away from it for now.

    I have 2 L-00 style guitars about to get my stain, epoxy fill, and Enduro-var topcoat treatment unless someone can steer me to a better method. I don't want a layered colored lacquer sunburst. I do want a hand rubbed 1930s style dyed finish. I don't see how applying a grain filler prior to staining will work. The filler will not accept dye nor will it blend into the 'burst. Unless, I'm missing something...
    Last edited by bpatrick; Nov-09-2020 at 3:16pm. Reason: Additional Info

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    Default Re: Epoxy pore fill and sunburst

    Are you absolutely determined that you are going to use epoxy? There are other solutions to this problem. Other ways to effectively fill the grain. I've used epoxy to fill grain on guitars, but only because I didn't want to use a colored filler. If I was going to dye it, I wouldn't use epoxy.
    I would agree with Dale on this. There are many other ways to fill pores. Epoxy is an excellent clear pore filler, one of the best, but is tricky if you are using dyes. It is also very messy and stinks, and is easier to use on a flat surface such as back and sides of a flat top guitar. On an arch top mandolin it gets really messy, you can't level it with a plastic card like on a guitar. I know, I have done one arch top mandolin with Z-poxy and never again. On guitars if I use epoxy pore fill I use Boat Coat epoxy which is a modern Australian developed epoxy originally developed for boat building that is much less toxic and does not stink anywhere near as much. Otherwise I use Aqua Coat to pore fill, and seal with shellac before using the Aqua Coat so as to fix the stain (if I use stain). MUCH easier, and not messy.
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    Default Re: Epoxy pore fill and sunburst

    Thanks everyone, all points noted. I do intend to experiment further before any decision is made. Peter, I have given up on Aquacoat as it never seems to fill the grain even after 4 coats. It looks ok until you put finish on, and then you see the pores(at least for me anyway).
    cheers Mike

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    Default Re: Epoxy pore fill and sunburst

    You might want to experiment, but I and a few other builders have had some really good results using things like drywall compound and products like that. Depending on your goal, you can tint them before applying, they may take dye well enough to put in out of the can. When the water in them dries, the shrinking is over. They sand easily. Think of it like filling the grain with plain or tinted plaster of paris. Stable after it dries. Unaffected by chemicals, for the most part.

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    Default Re: Epoxy pore fill and sunburst

    Mikeyb2: Please post your results later. I'd like to see how it works out for you.

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    Default Re: Epoxy pore fill and sunburst

    Much of this conversation is perplexing to me.
    It would seem to me that epoxy acts as a sealer, and that any attempt to get wood to absorb stain evenly after a sealer has been applied would only end in frustration, no matter how much one sanded the sealed surface.

    It would seem to me that the only way to get good color control once epoxy is applied would be to put all of the color into the finish. If you want to build color into the wood, you might be better off laying the color into the wood before you apply your filler. And you might want to consider something other than epoxy to use as a filler.

    My discipline is repair, not construction, and I don't claim much knowledge on new finishes from scratch. I do know that the only times I sunbursted mahogany, I used aniline alcohol dye directly on the bare wood, followed it with several coats of nitro, levelled it carefully, and then applied my finish coats. The early coats of nitro were sufficient to fill the pores after level sanding. But that was on ~70 year old guitar necks. I don't know if that technique would fill the pores well enough on new wood.

    And, when in doubt, practice on test boards.

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    Default Re: Epoxy pore fill and sunburst

    And if all of this wasn’t sufficiently perplexing, we can add in the great mystery of unfinished versus finished interiors. This question is still echoing in the violin community: did the great masters seal, and with what?
    Despite the interesting testimony of the lady in Palm Beach about everything’s gotta breathe, most woodworking advice is that thin panels need equal coatings on both sides to avoid warping from humidity changes. It appears that most, or all modern instrument finishes are diffusion barriers, and are put only on one side. Some theory invokes repairability, other, that there are acoustic issues. But to an outsider, like me, both sides should be sealed.

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    Default Re: Epoxy pore fill and sunburst

    I don't seal on the inside and never will. I also do repairs and sealing on the inside is a guaranteed repair nightmare. No coating is moisture proof, they just slow it down a bit.
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    Default Re: Epoxy pore fill and sunburst

    Your samples look good. I used Silver Tip on some guitars last year and it came out beautifully. The advantages over ZPoxy are the lack of amine bloom, as you discovered, and less amber color. It's pretty amazing stuff. The issue I discovered is that if you don't wear gloves religiously you can hinder adhesion between coats of epoxy with oils from your hands.

    I would suspect the main possible dangers with your method would be disturbing the dye while applying the epoxy and sanding through (obviously). If it doesn't seem like it disturbs the dye, it seems like it might be a viable option.

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