Official Luthiers Forum! :: View topic - Do you sand back to wood?

I would like to add something about thinned DNA. Back when Todd Stock et al were around, there was much discussion about it. I always heard 10% DNA. Never mind the fact that I could not estimate that! But if it was lightly thinned, I could not wipe it on (using a lint free/low lint paper towel etc). I've always had great results with blue paper towels. I always thin to excess. This is my final coat and it is only meant for color matching. I often find I need to add more DNA as I go since it appears to evaporate quickly. If I do not get clean, tackless wipes, I add a little more.

Other than that, Todd Stock's advice on how to apply has never failed me.

Mike

Mike OMelia wrote:

This guy calls it a wash coat https://www.youtube.com/watch?v=wvS98dojNVs

This thread is a big help to me guys / girls. Thank you so much.
At this point I have 2 cured coats of ZPoxy finishing epoxy cured and the back is almost leveled.
As many of you have pointed out it’s really hard to do without sanding through in some spots.
I think the thinned coat or 2 at the end may be my fox to color match

So is 50% alcohol good for this thinned mix or should I use more?

Sent from my iPhone using Tapatalk

Not to derail the thread, but I have a question.
I used Zpoxy on my last build, a tele type electric. It worked fantastic, but that was a few years ago. I cannot remember what I did re the plastic binding I used.
My current build is an acoustic, and I'm using vinyl binding around the top and back. I would like to use Zpoxy again.
Does anyone know if I need to tape up the binding, or if the Zpoxy will hurt it in any way?
Also, my Zpoxy I have left is at least 3 or 4 years old. Does it have a shelf life/do I need new?
Thanks

One other note: The manufacturer recommends using it at a temperature above 69 degrees. Before I knew that, I tried using it once at around 65 degrees and it didn't harden fully. It stayed slightly gummy.

Author:	SnowManSnow [ Sun Jan 27, 2019 2:10 pm ]
Post subject:	Do you sand back to wood?
So following an epoxy pore fill do you sand back down to wood level or do you try and keep an even think layer of epoxy? I’ve heard both ways. Just wondering what you guys prefer. Thanks B Sent from my iPhone using Tapatalk

Author:	jfmckenna [ Sun Jan 27, 2019 2:55 pm ]
Post subject:	Re: Do you sand back to wood?
I sand back to wood.

Author:	Glen H [ Sun Jan 27, 2019 2:56 pm ]
Post subject:	Re: Do you sand back to wood?
I don’t. If I do, I pad a thinned coat over all.

Author:	phavriluk [ Sun Jan 27, 2019 3:02 pm ]
Post subject:	Re: Do you sand back to wood?
on the three guitars I built, I block-sanded the epoxy filler coat back to level; there were a few exposed areas of wood, and I wiped on a thin final sealer coat over the whole body and then left it alone, the rest of the finish followed. I wanted to have a sealed consistent surface, and I thought that I'd have some adventures getting the whole finish to look even without the islands of grain showing up in the sea of epoxy. Worked for me.

Author:	Freeman [ Sun Jan 27, 2019 3:22 pm ]
Post subject:	Re: Do you sand back to wood?
I sand back to wood, then put one more coat thinned with a great deal of DA (1:3 or so, I don't measure). That gives me the final grain popping application which is one of the reasons I use Zpoxy in the first place.

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Author:	Colin North [ Sun Jan 27, 2019 3:36 pm ]
Post subject:	Re: Do you sand back to wood?
I admit I have been singularly unsuccessful at epoxy fill sanding back evenly to the wood, and anyway I prefer the grain pop of a layer of eoxy all over. Usually I do 3 coats zpoxy, sanding after each, filling the pores and levelling, careful not to expose any more pores. Then I dilute a little prepared zpoxy with about 10/12 parts alcohol and wipe/pad with clean paper towels quickly all over, doing 3 coats or so. Alcohol flashes off very quickly. After these coats xpoxy dry, scuff with scotchbrite pad, taking any nibs/dust/insects etc off with a single edged razor blade as I go. Then just move on to finishing schedule.

Author:	Mike OMelia [ Sun Jan 27, 2019 3:38 pm ]
Post subject:	Re: Do you sand back to wood?
I do not sand back to wood on purpose. But I find it unavoidable. To much wood exposure to sanding and new pores open. On my final go, the body will be smooth, with splotchy areas of exposed wood, rest covered in epoxy. Then I do a highly thinned wash (DNA). Next day I scuff sand and spray with Prestech 58x1/58x2 sealer and adhesion promoter. BTW, before I apply epoxy, I use the same sealer to minimize wood oil flow. Mike

Author:	J De Rocher [ Sun Jan 27, 2019 3:39 pm ]
Post subject:	Re: Do you sand back to wood?
I sand back to wood and finish with a wiped-on coat of z-poxy diluted 50:50 with denatured alcohol.

Author:	Mike OMelia [ Sun Jan 27, 2019 4:14 pm ]
Post subject:	Re: Do you sand back to wood?
I would like to add something about thinned DNA. Back when Todd Stock et al were around, there was much discussion about it. I always heard 10% DNA. Never mind the fact that I could not estimate that! But if it was lightly thinned, I could not wipe it on (using a lint free/low lint paper towel etc). I've always had great results with blue paper towels. I always thin to excess. This is my final coat and it is only meant for color matching. I often find I need to add more DNA as I go since it appears to evaporate quickly. If I do not get clean, tackless wipes, I add a little more. Other than that, Todd Stock's advice on how to apply has never failed me. Mike

Author:	meddlingfool [ Sun Jan 27, 2019 4:15 pm ]
Post subject:	Re: Do you sand back to wood?
Nope, I leave a layer...

Author:	Colin North [ Sun Jan 27, 2019 4:21 pm ]
Post subject:	Re: Do you sand back to wood?
Mike OMelia wrote: I would like to add something about thinned DNA. Back when Todd Stock et al were around, there was much discussion about it. I always heard 10% DNA. Never mind the fact that I could not estimate that! But if it was lightly thinned, I could not wipe it on (using a lint free/low lint paper towel etc). I've always had great results with blue paper towels. I always thin to excess. This is my final coat and it is only meant for color matching. I often find I need to add more DNA as I go since it appears to evaporate quickly. If I do not get clean, tackless wipes, I add a little more. Other than that, Todd Stock's advice on how to apply has never failed me. Mike This guy calls it a wash coat https://www.youtube.com/watch?v=wvS98dojNVs

Author:	Mike OMelia [ Sun Jan 27, 2019 4:46 pm ]
Post subject:	Re: Do you sand back to wood?
Colin North wrote: Mike OMelia wrote: I would like to add something about thinned DNA. Back when Todd Stock et al were around, there was much discussion about it. I always heard 10% DNA. Never mind the fact that I could not estimate that! But if it was lightly thinned, I could not wipe it on (using a lint free/low lint paper towel etc). I've always had great results with blue paper towels. I always thin to excess. This is my final coat and it is only meant for color matching. I often find I need to add more DNA as I go since it appears to evaporate quickly. If I do not get clean, tackless wipes, I add a little more. Other than that, Todd Stock's advice on how to apply has never failed me. Mike This guy calls it a wash coat https://www.youtube.com/watch?v=wvS98dojNVs Yes, that is exactly how I do it, how I feel about it. But lacquer thinner??? That would never have occurred to me. Had NO idea it was compatible. Gonna try that.

Author:	SnowManSnow [ Sun Jan 27, 2019 5:23 pm ]
Post subject:	Do you sand back to wood?
.

Author:	SnowManSnow [ Sun Jan 27, 2019 5:28 pm ]
Post subject:	Re: Do you sand back to wood?
SnowManSnow wrote: This thread is a big help to me guys / girls. Thank you so much. At this point I have 2 cured coats of ZPoxy finishing epoxy cured and the back is almost leveled. As many of you have pointed out it’s really hard to do without sanding through in some spots. I think the thinned coat or 2 at the end may be my fox to color match So is 50% alcohol good for this thinned mix or should I use more? Sent from my iPhone using Tapatalk Sent from my iPhone using Tapatalk

Author:	phavriluk [ Mon Jan 28, 2019 12:56 pm ]
Post subject:	Re: Do you sand back to wood?
New information arrives every day - - - I'd been wondering why a guitar neck that I'd finished satin-smooth with Z-poxy and nitrocellulose lacquer turned rough at the surface after six months of use. Perhaps the aging Z-poxy I used is involved in the mystery. I'll never know, it's all gone now. I think a good takeaway from this discussion is to use fresh materials when finishing. I know we all regret discarding stuff that seems perfectly usable, but using it might cause future disappointment. And the finishing materials are inexpensive from the perspective of total project cost.

Author:	Clay S. [ Mon Jan 28, 2019 1:43 pm ]
Post subject:	Re: Do you sand back to wood?
Some epoxies will thicken and crystalize over time and must be rejuvenated by warming them in a water bath (@120F for system 3).

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Author:	Mike Baker [ Sun Jan 27, 2019 9:03 pm ]
Post subject:	Re: Do you sand back to wood?
Not to derail the thread, but I have a question. I used Zpoxy on my last build, a tele type electric. It worked fantastic, but that was a few years ago. I cannot remember what I did re the plastic binding I used. My current build is an acoustic, and I'm using vinyl binding around the top and back. I would like to use Zpoxy again. Does anyone know if I need to tape up the binding, or if the Zpoxy will hurt it in any way? Also, my Zpoxy I have left is at least 3 or 4 years old. Does it have a shelf life/do I need new? Thanks

Author:	J De Rocher [ Sun Jan 27, 2019 9:31 pm ]
Post subject:	Re: Do you sand back to wood?
Mike Baker wrote: Not to derail the thread, but I have a question. I used Zpoxy on my last build, a tele type electric. It worked fantastic, but that was a few years ago. I cannot remember what I did re the plastic binding I used. My current build is an acoustic, and I'm using vinyl binding around the top and back. I would like to use Zpoxy again. Does anyone know if I need to tape up the binding, or if the Zpoxy will hurt it in any way? Also, my Zpoxy I have left is at least 3 or 4 years old. Does it have a shelf life/do I need new? Thanks The official shelf life of z-poxy is one year. I just did pore filling with z-poxy I bought almost three years ago and it behaved exactly like all the other times I used it from those two bottles so it seems fine to me. To be safe, you might want to test yours on a piece of scrap wood sanded the same as you would do for a guitar to make sure it's still ok and sets up properly. I haven't used z-poxy on plastic binding so I don't know the answer to that question. You could also do a test for that to see how it works. One other note: The manufacturer recommends using it at a temperature above 69 degrees. Before I knew that, I tried using it once at around 65 degrees and it didn't harden fully. It stayed slightly gummy.

Author:	Mike Baker [ Sun Jan 27, 2019 10:01 pm ]
Post subject:	Re: Do you sand back to wood?
Thank you, Jay. Appreciated.

Author:	Chris Ensor [ Sun Jan 27, 2019 10:45 pm ]
Post subject:	Re: Do you sand back to wood?
Nope. Love the added depth epoxy pore fill gives to the look of the finished product.

Author:	DennisK [ Sun Jan 27, 2019 11:01 pm ]
Post subject:	Re: Do you sand back to wood?
J De Rocher wrote: One other note: The manufacturer recommends using it at a temperature above 69 degrees. Before I knew that, I tried using it once at around 65 degrees and it didn't harden fully. It stayed slightly gummy. Yeah, epoxies love heat. I've never used it for pore filling, but in general the higher your room temperature, the faster it will set up (important if you want to sand it the next day, because you don't want partially cured epoxy dust getting in the air and on your skin). If possible, put the guitar close to the ceiling where it's warmer, especially in the winter.

Author:	WudWerkr [ Mon Jan 28, 2019 10:33 am ]
Post subject:	Re: Do you sand back to wood?
depends on the wood, some woods you create new pores when sanding back to wood. i try to leave a thin layer

Author:	Clay S. [ Mon Jan 28, 2019 11:29 am ]
Post subject:	Re: Do you sand back to wood?
@ Mike Baker, Most epoxies don't react with plastics. I bind with PVC edge banding as used for cabinets and have never had it react with West systems epoxy. Polyester resin will react with polystyrene.

Author:	Mike Baker [ Mon Jan 28, 2019 11:40 am ]
Post subject:	Re: Do you sand back to wood?
Thanks, Clay. Much appreciated.

Author:	Pat Foster [ Mon Jan 28, 2019 12:17 pm ]
Post subject:	Re: Do you sand back to wood?
Mike Baker wrote: Not to derail the thread, but I have a question. I used Zpoxy on my last build, a tele type electric. It worked fantastic, but that was a few years ago. I cannot remember what I did re the plastic binding I used. My current build is an acoustic, and I'm using vinyl binding around the top and back. I would like to use Zpoxy again. Does anyone know if I need to tape up the binding, or if the Zpoxy will hurt it in any way? Also, my Zpoxy I have left is at least 3 or 4 years old. Does it have a shelf life/do I need new? Thanks I've had issues with expired Z-poxy, where all goes well during finishing, then months later, the pores "erupt," leaving small bumps on the surface. YMMV.