Clear grain filler - Waterborne? Epoxy?

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Steve Sawyer
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Clear grain filler - Waterborne? Epoxy?

Post by Steve Sawyer »

I didn't want to muddy up what is an excellent thread on waterborne finishes, but noted references to epoxy fillers.

I've used paste grain fillers on furniture projects, but that's the conventional filler that has been used in woodworking since the late Pleistocene era. I have no familiarity with epoxy for this purpose, but given the challenges in getting the conventional fillers to match the wood when using a clear finish, a clear filler product sounds interesting.

Doing a google search comes up with a few products - things like Crystalac Clear Waterborne filler which I found at Rockler, Aqua Coat (another waterborne filler), Z-Poxy finishing resin and System III Epoxy Filler, all available from LMI.

I have to admit that I'm a bit intimidated at the idea of using a 2-part epoxy. I don't see any working times quoted in the listings, and my experience is that epoxy is a b**ch to sand.

I'd be interested in getting some thoughts and experiences of folks using any of these or other similar products as a grain filler under a clear finish.

Thanks!
==Steve==
Gordon Bellerose
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Gordon Bellerose »

More than a few people here have commented negatively on the Crystalac product.
I have tried it a couple of times without much success. You have to work quickly with it, as it dries very hard very quickly. You cannot see it, so sanding it is difficult. It didn't work well as a filler.
The two part epoxy works very well, but does darken the color a bit. You have to take this into account when planning your colors.
Mixing it is simple. Just measure into a tablespoon part 1. Use half that much with part 2. Mix on a flat piece of wood/plastic/wax paper, with a small stick. The mix is usually 2:1, but your product will have instructions. Working time is great; over an hour for most products.
I use a small squeegee to level it. Yes; sanding can be difficult, but the ease of leveling makes epoxy my filler of choice.
It goes a long way. I have found that 1 tbsp. of part 1, and a half tbsp. of part 2, is enough to do both sides of a solid body guitar.

Todd Stock, one of the forum members, has a video on Youtube showing how to use epoxy. It is what I used to learn how to use epoxy.
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Craig Bumgarner
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Craig Bumgarner »

I like epoxy for grain fill. It is clear, gets hard, no question about adhesion, does not shrink. It sands well enough, but if you are doing it right, there is not much sanding to be done.

I use System Three, mostly because it is very clear and does not get an amine blush. Amine blush attracts moisture and can interfere with subsequent coats. It is easy to remove with warm water w/ a little soap or ammonia. I don't like water on guitars, at this stage at least, so the fact that System Three does not blush is an advantage. Epoxy is not hard to use as long as you know a few of the tricks.

One of the tricks to a good cure is accurate measurement. Because small batches are used, strongly suggest getting a digital gram scale. They are on Amazon for ~$15. To fill back, sides and neck takes about 12 grams for the first filling and 7 grams for successive coats. Measure carefully. I download parts A and B to squeeze bottles for neater dispensing. Mix well and then mix again. Some mix colloidal silica (Cabo-Sil) to thicken, but I don't.

Second trick is a good trowel. Behlin makes one. A credit card will do in a pinch. Sand surfaces well to what ever you think you need. I sand to 320 most of the time and then sweep with 1000 to burnish up the surface a little. Clean surface well as dust will mix with the epoxy and leave shallow groves in the fill. Mix up epoxy and trowel on. On the neck, I use an alcohol soaked cloth to wipe the epoxy smooth. Try not to leave ridges as these will have to be sanded out. First coat will not fully fill. Allow to cure about 8-12 hours depend on temp. Block sand. If you break through, don't worry, the next coat will blend in.

I usually fill three times or whatever it takes to get a dead flat surface. If I have broken through which I usually have, I apply a wiped coat with epoxy and an alcohol rag which will feel almost like French polish. A very light scuff sand is all I do for the next step in the finishing process.

Clean trowels with rag and alcohol as best you can, but you will probably have to sand the edges before using them again. Work neat and try not to get it on you. I always use disposable vinyl gloves from the drug store when handling epoxy. A respirator in an enclosed environment is advisable though I personally don't find epoxy fumes bothersome, a fan is all I use frequently.
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Re: Clear grain filler - Waterborne? Epoxy?

Post by David King »

West Systems (Gougeon brothers) finishing epoxy (105-207) is my first choice for grain filling as it has UV blocker, sets up hard in a reasonable period of time and is extremely easy to sand. Mixing is made easy via the dosing pumps that come with it. I have also used it as the final finish and find that it buffs out to a high gloss and makes a hard durable finish.
The challenges I have with epoxy are mixing it without introducing bubbles and keeping it cool during mixing and application in warm weather. The bubbles aren't so much an issue with grain filling but they are with finish. To keep it cool I put my mixing cups on ice.
The one thing I'd add to all the advice above is to mix in a first cup for the recommended 2 minutes and then transfer to a second cup and continue mixing with a new stick. This I have found to be indispensable to get a thorough mix. Not doing this extra step has caused me some grief when the finish looses it's moisture resistant properties after 5-10 years.
I'm still looking for a reliable way to eliminate the bubbles. My current vacuum pumps don't help at all. Passing a flame or using a hair drier seems to pop the largest bubbles but has no effect on the smaller ones. There are mixing systems are are supposed to keep the bubbles out and I might try one of those next.
The other issue with epoxy is that you need to watch out for heat build up when buffing or you will get grain sink.
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Todd Stock »

West 105/207, MAS Low Viscosity with Fast or Slow hardener, or System 3 Silver Tip all are non-blushing, clear epoxies for laminating and coating - all will work for what we do with them. Z-Poxy does blush, and adds amber color to the mix (the hardener darkens from a light amber to something like garnet shellac over time), is the easiest to use of the five or six brands I've had in the shop...but it also shrinks back over time, so I've gone to West 105/207 until that material is gone (I buy gallon cans of the resin, so it takes a while). System 3 Silver Tip Laminating Resin looks to be the best bet at this time for a non-blushing epoxy that resists any shrink-back, and work under just about any topcoat. It addresses the #1 issue I have with 105/207, which is the slow cure time to sanding/scraping.
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Steve Sawyer
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Steve Sawyer »

Odd - I could swear I posted a reply to this thread the other day - musta been a "senior moment". :roll:

Anyway, I did watch Todd's videos (Thanks, Todd!!) - very informative.

Todd - since you've jumped in here, is the System Three product you are currently recommending fussy about proportions? Not a big deal as it appears from your videos that even with the initial application you're mixing up a very small amount at a time, and it's probably easier to do that by weight anyway. The downside is that the smaller the quantity, the more important it is to have a very accurate scale to get the resin/hardener ratio right.
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Steve Sawyer
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Steve Sawyer »

Let me ask another question - any reason you couldn't use epoxy as a filler under a painted finish? I was planning on using conventional paste filler and sanding sealer on the project I have going now, but maybe it's an opportunity to give epoxy a go...
==Steve==
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Bryan Bear
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Bryan Bear »

I've never (yet) used epoxy pore fill. Is Blush really an issue for pore filling guitars? I've never even thought of it while kicking around the idea of switching to it. It seems to me that the conditions we keep out instruments in during construction (stable temperature and humidity) that blushing is more of an academic point than real concern. But, like I said, I haven't done it yet. Has anyone had problems with blushing? I ask because when do first try epoxy, I had planned to use Zpoxy. It is slightly more convenient for me to acquire than West, I like the slight amber and it might be a little more user friendly for a first go. If Blushing is a real factor, I might change my mind. . .
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Gordon Bellerose
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Gordon Bellerose »

I have not had an issue with blushing. (Maybe a couple of times when I was younger, and got caught with the wrong.....Oh never mind) :oops:
I live in a climate that usually has lower humidity levels, so that may be a large contributing factor.
Rarely, except when it rains, does the humidity get above 50%.
I think once you try epoxy, you will quickly grow to like it. Much less work that some of the old methods.
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Barry Daniels
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Barry Daniels »

Epoxy doesn't blush from humidity, but it can get a condition called amine blush. And that can be easily sanded off if it happens, but it is not common.
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Todd Stock
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Todd Stock »

Amine blush is more visible with higher humidity during cure - it's still there whatever the RH is low or high, but begins to look like classic high RH finish blush with high RH...hence, the confusion.

Unless the epoxy is a blush-free formulation, assume the blush is there and wash, then sand to remove. The water/detergent was is the biggie...sanding is belt-and-suspenders.

All System Three stuff seems mix sensitive, but I think that - other than systems with a 1:1 mix, every one of the brands I've tried small amount mixes (under an ounce) range between picky and never again. I've stopped mixing 105/207 in batches smaller than an ounce, and MAS with slow hardener seems just about as sensitive. I've only used a small sample of the Silver Tip, but it is surprisingly good for a system 3 product - all the small batches (10 grams, etc.) cured up nicely.
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Steve Sawyer
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Steve Sawyer »

Todd Stock wrote:I've stopped mixing 105/207 in batches smaller than an ounce, and MAS with slow hardener seems just about as sensitive. I've only used a small sample of the Silver Tip, but it is surprisingly good for a system 3 product - all the small batches (10 grams, etc.) cured up nicely.
So System Tree Silver Tip can be mixed well in small batches. I'm assuming you're mixing by weight - I note that product mixes at 100:44 by weight. That would take a good scale for a 10-gram batch!
==Steve==
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Craig Bumgarner »

Have a look on Amazon, the ones that look like the pic below are ~ $14, prime. Multiple sellers. I have two and mix batches of System 3 as small as 2.5 : 1.1 grams successfully. When I go that small, I dispense on to a piece of scrap acrylic sheet and mix on the flat instead of a cup.
digital scale.jpg
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Bryan Bear
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Bryan Bear »

Todd Stock wrote:Amine blush is more visible with higher humidity during cure - it's still there whatever the RH is low or high, but begins to look like classic high RH finish blush with high RH...hence, the confusion.

Unless the epoxy is a blush-free formulation, assume the blush is there and wash, then sand to remove. The water/detergent was is the biggie...sanding is belt-and-suspenders.

All System Three stuff seems mix sensitive, but I think that - other than systems with a 1:1 mix, every one of the brands I've tried small amount mixes (under an ounce) range between picky and never again. I've stopped mixing 105/207 in batches smaller than an ounce, and MAS with slow hardener seems just about as sensitive. I've only used a small sample of the Silver Tip, but it is surprisingly good for a system 3 product - all the small batches (10 grams, etc.) cured up nicely.
So when using, say, zpoxy and leaving a skim coat on the wood (not sanding back and leaving it in the pores) everyone should be washing before finish? This is the first I have read about this. If you can't see it and assume it is there, how do you know you have washed and rinsed enough?
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Steve Sawyer
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Steve Sawyer »

Craig Bumgarner wrote:Have a look on Amazon, the ones that look like the pic below are ~ $14, prime.
Great - thanks, Craig.
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Re: Clear grain filler - Waterborne? Epoxy?

Post by David King »

As I understand it the amines migrate to the surface during the cure and simply need to be wiped up, they are water soluble but a little detergent helps. You can also sand or scrape them off the surface however sanding may leave some residue.
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Bob Gramann »

Just and aside and a new direction: Target Coatings has a new filler HSF 5000 that you brush on and sand level. I bought some and am in the process of trying it. Two coats got a mahogany surface to what seems like well filled and level. I haven't sprayed finish yet. I will report back when I finish finishing.
with any method, it seems like perfectly filled pores always show up not so perfect after the finish is sprayed.

Over the years, I have used epoxy and CA and abandoned both because of the fumes. I have used traditional grain fillers, Aquacoat, Timbermate, and pumice(as in French polish). I keep going back to the pumice--it's pretty predictable and seems to be less work (even thought it takes three applications). Every now and then, I use Timbermate when I want contrasting pores.
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Craig Bumgarner »

FWIIW, I've mixed hundreds of small batches (10 grams or less) of System Three, SB112 (and WEST) using the above digital scales and never had a bad batch. I'm picky about getting the measurement right and have been known to throw out a mix unused if I think I might have gotten it wrong. Decanting parts A and B to squeeze bottles (Amazon) make for drop by drop additions to the mix, one drop = ~.04 grams. If you are careful, you can get very accurate mixes pretty easy.

If Sys 3 blushes at all, it is not much. Sanding it after curing 12 hours is dusty without paper buildup like you get with standard WEST when it blushes. Scraping the cured epoxy works better than sanding. Scraping cuts the blush off, sanding can just move it around. I use a standard card scraper, freshly sharpened. Scrape first, then some block sanding with 320.

Some products you might put over blushed epoxy may not like it because of the moisture it attracts. When you put epoxy over epoxy, it isn't the amine, it's the moisture drawn to the amine. Curing epoxy does NOT like moisture. I've been told shellacs do not like the amine itself, so if you go from epoxy fill to shellac, good to get all the amine off. Wipe wet rag before sanding is usually enough.

The nice thing about epoxy fill is it does not shrink back and if you get the surfaces dead flat before moving on to the next stage, less finish is needed. The epoxy fill does not have to have much film thickness overall, I sand back each coat pretty hard and then wipe the last coat with an alcohol soaked rag to get even color. This last coat just needs a very light sanding before the next stage.

Right or wrong, I only use System 3 for grain filling. For most any other usage, such as fingerboards, back and side laminating, I use WEST. No epoxy is cheap, but WEST is considerably less per volume than System Three.
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Steve Sawyer
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Steve Sawyer »

Bob Gramann wrote:Just and aside and a new direction: Target Coatings has a new filler HSF 5000 that you brush on and sand level.
In looking at Target's description of this, I assume you're using the "neutral" variant. Did you need to tint it at all to match the color of the mahogany?
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Re: Clear grain filler - Waterborne? Epoxy?

Post by Bob Gramann »

No tint. I used the neutral version which is clear. The pores look dark. It looks good under shellac. Unfortunately, I won't be spraying the finish for a couple of more weeks. The heat intervened this week and other events will intervene next week.
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