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Epoxy pore filling revisited - help with neck, please
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Author:  Todd Rose [ Fri Mar 28, 2014 10:10 am ]
Post subject:  Epoxy pore filling revisited - help with neck, please
Hi all,

I'm using epoxy (Z-Poxy) for pore filling for the first time. I've read what I could find in the archives and watched Todd Stock's very helpful videos on YouTube. I've gotten a good start on the back -- the nice, flat surface to work on makes that pretty straightforward (although still a bit of a learning curve). The neck, however, presents another challenge (too bad Todd S. hasn't done a vid on that). My first attempt at applying it with a gloved finger resulted in way too much excess epoxy left on the surface. Thankfully, the cured Z-Poxy sands very easily, so it wasn't nearly as bad sanding back as I was afraid it might be. But, I don't want to repeat that. I've been brainstorming possible methods to remove the excess epoxy from the curved and contoured surface of the neck after working it into the pores. Since these contoured surfaces are also more difficult to level-sand evenly, it would be nice to complete the first step having succeeded at removing the excess epoxy, leaving a thin film and an already nearly-level surface, as Todd demonstrates doing with a squeegee on the back and sides. Before I dive in again, do any of you have a method that works well for you that you'd be willing to share?

This is the neck in question:

Image

For any of you who may be interested, here's a build thread for this guitar on the AGF. I'll be finishing it with a brushed varnish, using Epifanes. (Some of you may recall the thread I started about varnish choices a while back. I'm finally now getting to work on the finish, so I'll have some results to post before too long.)

http://www.acousticguitarforum.com/foru ... p?t=285710
Author:  johnparchem [ Fri Mar 28, 2014 10:46 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
I use my gloved finger to remove the excess zpoxy on the neck. Just like with the squeegee I wipe the zpoxy off my finger with a Da soaked rag to avoid reapplying what I have taken off.
Author:  Freeman [ Fri Mar 28, 2014 11:14 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
I've had good luck thinning the zpoxy slightly with denatured alcohol and using a thin plastic card to spread and scrape it. I usually do two or three very thin applications and there is always some sanding

Image
Author:  Colin North [ Fri Mar 28, 2014 12:01 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Heat.
Use a heat gun and a foam brush to apply it.
Have a look at Pat Hawley's posts on the subject..
Author:  Todd Rose [ Sat Mar 29, 2014 6:30 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Thanks to each of you for the input!
Author:  Hesh [ Sat Mar 29, 2014 6:32 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Howdy Todd!

To directly address your questions here's what I do and what I have found works best for me.

I like Z-Poxy "finishing resin" and I'm always sure to qualify which Z-Poxy I'm using because Z-poxy comes in other formulations too, epoxy glue which is not the same viscosity as the "finish resin."

Or West works great with the following method.

My goal for the fist coat is to get some epoxy into the very bottoms of the pores. I find that getting the initial coat to stick without it wanting to sand out is really the only problematic area when using epoxy as a pore filler (beyond health precautions).

So my first coat goes on straight-up, mixed as per the instructions be it West or Z-Poxy FR. Because the viscosity is thinner straight-up I think that it gets to the bottom of the pores better.

Once the pores are wetted with cured epoxy the second coat will stick like glue, er, well.... it is glue.... right.... :)

So for the second coat I thicken with micro balloons to the consistency of cold cream giving the filler more body and better filling qualities in fewer sessions.

Usually for me the second coat thickened is all I have to do and then these days I let it cure for a day and then sand back to bare wood. You most certainly can wet a final "wash coat" with a thinner and wipe it on to even out color too.

The squeegee thing never worked for me because my technique using a credit type card (AARP....... gaah :D seems to keep me supplied with cards lately.... how insulting..... :D ). Using the card as a squeegee but also using the card to mash the stuff/downward into the pores seems to do the trick. I work the epoxy from all directions mashing the epoxy into the pores and then I use the stinkin AARP card to "squeegee" in the verb sense the excess off.

So I use it straight-up initially and thicken for subsequent coats. I don't heat the epoxy at all.

Necks are the same but with a nitrile gloved finger that I know where that finger has been.... I work the epoxy into the pores, straight-up for the first coat and thickened for the subsequent coats. I find that necks may need three applications and bodies often only two.
Author:  B. Howard [ Sat Mar 29, 2014 9:19 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
FWIW lacquer thinner makes a better reducer for epoxies than DA.
Author:  Pat Hawley [ Sat Mar 29, 2014 9:56 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
As Colin already said, warm it up (a hair dryer is all you need) and paint it on with a foam brush. Personally, I've never been able to get a ridge free, even coat any other way.

Pat
Author:  Todd Rose [ Sat Mar 29, 2014 10:02 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Hesh wrote:
Necks are the same but with a nitrile gloved finger that I know where that finger has been.... I work the epoxy into the pores, straight-up for the first coat and thickened for the subsequent coats. I find that necks may need three applications and bodies often only two.


Thanks for your input, Hesh. Hope all's well in Ann Arbor -- my old stompin' grounds (from '81 through '96), as you may recall.

Do you use a card or any other implement to "squeegee" the excess epoxy off the neck, or do you just do that with the gloved finger? I thought I was getting about as much of it off as I could with my finger, but there was still a lot of excess to be sanded back -- especially because the excess epoxy coalesced somewhat on the surface as it cured, leaving the cured material significantly lumpier than it had been when wet. Maybe I simply need to try harder on my second attempt... it just seems like a finger has no edge to scrape across the surface and effectively remove the excess epoxy.
Author:  LarryH [ Sat Mar 29, 2014 10:24 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Just visited that build thread and thoroughly enjoyed it. Incredible design and documentation. Makes my current little OM look pretty meager in all respects. I see you've decided on the Epifanes as a finish. Please let us know your experience. Love the lustre and the application of the Epifanes but it never got really hard for me. I'm back to using the Sutherland Welles U500.
Author:  Todd Rose [ Sat Mar 29, 2014 2:58 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Thanks, Larry! I will let you all know how it goes for me with the Epifanes.
Author:  Hesh [ Sat Mar 29, 2014 6:01 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Todd Rose wrote:
Hesh wrote:
Necks are the same but with a nitrile gloved finger that I know where that finger has been.... I work the epoxy into the pores, straight-up for the first coat and thickened for the subsequent coats. I find that necks may need three applications and bodies often only two.


Thanks for your input, Hesh. Hope all's well in Ann Arbor -- my old stompin' grounds (from '81 through '96), as you may recall.

Do you use a card or any other implement to "squeegee" the excess epoxy off the neck, or do you just do that with the gloved finger? I thought I was getting about as much of it off as I could with my finger, but there was still a lot of excess to be sanded back -- especially because the excess epoxy coalesced somewhat on the surface as it cured, leaving the cured material significantly lumpier than it had been when wet. Maybe I simply need to try harder on my second attempt... it just seems like a finger has no edge to scrape across the surface and effectively remove the excess epoxy.


Yeah I remember that you used to live in A2 as well and we missed you today at the gathering, maybe next time.

I just use a gloved finger but know what you are saying so I use one finger and remove excess, then a different finger, remove, until all fingers are gooey and then pitch the glove and use a clean one and repeat. With your hands you can get a lot of the epoxy off provided that what you remove is not being reapplied by using the same fingers and gloves.

It is messy and does require a bit more sanding to get a nice, uniform fill.
Author:  Todd Rose [ Sun Mar 30, 2014 6:34 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Thanks, Hesh.

I think I'll take a piece of scrap and experiment with heating the epoxy. I'll try applying it first, unheated, with a gloved finger, mashing it into the pores, then heating it with a heat gun and seeing if I can get it thin enough to remove the excess with a foam brush and end up with a nice, thin, smooth coat.

I will also try heating the epoxy first and brushing it on, and see if I observe a difference in how well it fills the pores with that method.

I'm very curious to see how thin it gets with heat. In theory, I love the idea of doing the final thin coat with heat-thinned epoxy rather than solvent-thinned epoxy, because my experience with solvent-thinned epoxy (which I've done a little of for other purposes, using alcohol) is that it cures to a significantly softer, rubbery state. The idea of having a softer, rubbery layer of material, however thin, under the top coats doesn't sit well with me.

Ultimately, I may decide to sand back to wood, anyway. Being that this is my first time doing this, that question remains open. But the epoxy sure does wet the wood beautifully, so, if I can leave a very thin and hard film of it on the wood, then seal that with shellac, and then onto the varnish, that would seem like a very good way to go, and probably easier than sanding back to wood. For that matter, I know some people put a coat of epoxy on the top as well; once again, if that is done with a very thin coat of heated epoxy that will cure hard, I can see advantages to doing that as well, such as making it easier to pore-fill the rosette and the top edge of the binding.

Anyway, thanks again to everyone for your input. Definitely very helpful.
Author:  Pat Foster [ Sun Mar 30, 2014 9:45 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Todd,

I preheat the neck for a few hours under lamps. It holds the heat better. The Z-poxy seems to take to the wood better when it hits a warmer surface, and it stays thinner with the neck staying warm longer. I've tried the credit card thing, which works well on the flat parts, but just use the gloved finger wipe everywhere else.

I couldn't make the foam brush work, but maybe that's just me. I'm leery of foam brushes with DA since the brush manufacturer advises against using them with shellac. I know acetone will dissolve the foam slightly and contaminate the finish, might happen with DA, but haven't tested it.

Yer gonna love that Epifanes. Self-levels like magic when brushed.


Pat
Author:  Todd Rose [ Sun Mar 30, 2014 12:32 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Thanks, Pat. Very helpful.
Author:  Todd Rose [ Mon Mar 31, 2014 8:33 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
I like your idea of preheating the neck, Pat. Giving it a little more thought, though, I'm wary of applying a steady heat with lamps for a few hours, even if it's a fairly gentle heat. It seems to me that, with that method, there's a risk of messing with the stability of the neck by over-drying the wood. Maybe that concern is unwarranted, but I'm thinking I'll try a quicker warming of the surface with a heat gun.
Author:  Todd Rose [ Mon Mar 31, 2014 1:46 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
First experiment with heating the Z-Poxy: utter failure. It got thinner, for sure, but not thin enough to brush it thinly and smoothly. It remained viscous and gooey enough to leave a too-thick and streaky-ridgey coat when brushed on -- definitely neither as smooth nor as thin a coat as I was able to do with the unheated epoxy and a squeegee. I kept trying to heat it more, but to no avail. I even eventually got it hot enough that when I dipped the foam brush into it, it started to melt the tip of the brush a bit.

I also tried applying some unheated epoxy with a gloved finger (working on the face of the headstock), working it into the pores, then heating it on that surface, then attempting to remove the excess by brushing over it with the foam brush. Again, no success with arriving at a thin, smooth coat using that method. I ended up squeegeeing it off with a credit card.

idunno
Author:  Todd Rose [ Mon Mar 31, 2014 5:04 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
It occurs to me that my experience with alcohol-thinned epoxy curing rubbery was that the epoxy in the mixing cup cured that way. I suspect that when the epoxy is spread thin, the alcohol evaporates out before the epoxy cures, so it may have no effect on the hardness of a thin cured film. I'm going to do a little experimenting with thinning some Z-Poxy with different amounts of alcohol and spreading it thinly on some test pieces to see what the cured film is like.
Author:  Glen H [ Mon Mar 31, 2014 7:18 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Todd
Good luck on working it out. I finally just gave up on epoxy as a filler on the neck shaft. I use it on the body, front and back of the headstock, but just use traditional pore filler on the back of the neck shaft. Takes just a few minutes and results are acceptable. I've had some shrinkage, but I've had shrinkage where I use epoxy also. Ymmv. I'm following this thread to see how it works out.


Sent from my iPhone using Tapatalk
Author:  weslewis [ Mon Mar 31, 2014 8:23 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
when spreading, keep heat going at all times...i.e. brush in one hand and the hairdryer in the other....on large surfaces like the back I like to pour some on spread with a squeegee, then with the hairdryer in one hand and a foam brush in the other finish spreading "painting" on the zpoxy, followed by a new dry foam brush, while still using heat, go over the surface which will soak up the excess and really smooth the surface...you will quickly become familiar with how much open time you have...the trick is to keep the heat going , no thinner is needed...I find the neck is the easiest part to do and with a little practice practically no sanding will be needed....When Pat first posted the thread I kinda hit myself upside the head , cause I too built RC planes for competition pattern flying and racing for many years, for those familiar with the AMA I have a 4 digit number which really shows my age!!! wow7-eyes but that's how we applied the fiberglass cloth to wings and never occurred to me to use the same method for pore filling...also make sure to use the finishing resin part number PT40...
Author:  Pat Hawley [ Mon Mar 31, 2014 8:28 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Sorry the heating isn't working for you Todd. My guess at what is happening is that you are making it too hot and making the z-poxy cure too fast. So the getting thin from the heat is losing out to the fast curing from the heat. I just use a hair dryer and I never get close to melting anything. You just need to warm it up. Even warming up will decrease the cure time but it should get thin and there will be ample time to get it spread out. Try it out on some scrap to get the temperature optimized.

Good luck,
Pat
Author:  Joe Beaver [ Mon Mar 31, 2014 11:27 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Heat is the way to go. I never thin epoxy. It leads to problems.

I heat the wood first with a hair dryer, put epoxy on a modest area with a gloved finger, heat it a little more, not to much, and brush with the foam brush. Keep moving along and don't go back over an area after you have moved along.
Author:  Todd Rose [ Tue Apr 01, 2014 3:57 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
I appreciate these more detailed tips on using heat. Sounds like more experimentation is in order.
Author:  Todd Rose [ Tue Apr 01, 2014 3:59 am ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
Joe Beaver wrote:
I never thin epoxy. It leads to problems.


What kinds of problems have you experienced?
Author:  Craig Bumgarner [ Tue Apr 01, 2014 2:57 pm ]
Post subject:  Re: Epoxy pore filling revisited - help with neck, please
On necks, I've had good luck squeegeeing epoxy on and then wiping down with an alcohol socket rag. The heat thing sounds like a good idea, just understand heat accelerates the cure and can also raise bubbles in the epoxy.

Regards varnish, my day job is in a yacht yard, we use a lot of varnish. Our favorite is Z-spar's Captain's varnish and for the last year that is what I've been using for finish on new guitars. I tested Captains vs. Epiphanes side by side and Captain's gets considerably harder. With Captain's, I am able to polish out to a finish gloss equivalent to nitro. You can brush it well and I have, but it takes more coats and more sanding between coats. Recently, after epoxy filling the grain, I've been spraying 4-5 coats to get a good base, sand this dead level with a cork block & 600 w/d, then 1-2 finish coats. I thin only as needed to get the varnish to lay down well. Sand out with cork block and 2000 w/d, buff on stationary buffer and Menzerna dry compound. Very professional looking finish. Very durable, resists most solvents, water, perspiration, sunlight, hard enough to protect cedar tops, easy to repair and smells good when you open the case for the first six months. Varnish is slower than nitro or water base lacquer to both apply and harden up for final buffing, but visually it is stunning, adds just the right amount of color and is much nicer to work with than nitro fume/health wise.
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