Epoxy observation....(OT?)

Uncured resin is an excellent solvent

Bill Tindall, E.Tn.

Uncured epoxy will dissolve the adhesive or at least lower its viscosity.

And, the way to remove stuck labels and tape is to heat it with a heat gun. Viscosity is highly temperature dependent. At low viscosity adhesive has little holding power.

Re: Epoxy observation....(OT?)

John in NM

It shouldn't be this hard. From the sound of things, youtube isn't doing you any favors either. An epoxy bath? Good heavens! Waaaaaay too wasteful!

We used to tape up the cracks on the bottom and sides with copious amounts of masking tape, then mix epoxy in a cut off soda can and pour it on. Mix more as needed, pour it on too. Let it puddle on the top, no need for dams. Often more would soak in than the puddle could provide, so once hard you pour more on.

Tape peels off fairly easily, but any that is stuck under epoxy (that does happen) comes off when planing or belt sanding. In that shop we used to face joint and plane close to dimension and then use a widebelt sander to finish. Mesquite is terrible for tearing out, hence the sander for the last ~1/16". Maybe that's what is missing here - do all that taping and filling long before you dimension to finished thickness. Who cares if it sticks? Planer will fix it!

If there was enough meat to the board, I would plane it down a bit first - the tape sealed a lot better on planed wood but I didn't always have that luxury. Excursions of epoxy out the bottom did happen too, especially with new staff who didn't use copious amounts of tape.

I'm sure packing tape is fine too. We used masking tape because it had just enough stick and not too much I think. Blue (or green) probably wouldn't have enough tack.

Duct tape

Waaaaay too sticky!

lets review

Bill Tindall, E.Tn.

problem: tape doesn't stick sufficient.

Solution: use tape with better adhesion

Downside: none,

Why is epoxy used for this application

Bill Tindall, E.Tn.

Has styrene or acrylic resin been considered?. Faster cure, Vastly cheaper.

Looking back on it....

Barry Irby

I would inlay patches of the same wood in the bottom side to seal the cracks and crevices. To keep them from showing on the ends I would stop them about and inch short so the epoxy would wrap around.

I have some 3/8" spiral carbide bits for the router and a 1/2" and a 1 1/4" collar for the router. A homemade inlay kit. Make a pattern, cut the recess with the 1 1/4" collar and then cut the fill piece with the 1/2" one. Works well.

I considered duct tape but did not have any at the moment. A friend had some that was about 3" wide and I started to borrow it, but did not. If there is a nest time I may try that. I may set up a test piece just to see.

Re: Why is epoxy used for this application

Barry Irby

No. Probably because I am an ignorant savage and did not know of them. I watched several YouTuber's and used what they used. They seemed to have a lot of experience over a number of years and I went with that.

Re: Looking back on it....More

Barry Irby

I sanded and cleaned where I stuck the flashing tape. Maybe 80 grit and blew it off. Turns out this epoxy was of such low viscosity it would find any hairline to leak through. Took it 24 hours to start to gel. Plenty of time to find any flaw. Or to soften the adhesion on the tape and work it's way through.

There were some bug holes in this wood (adds character). Know what a shot worm is? It's a bug that makes a hole about a 1/32" in diameter and amazingly straight. This stuff found a shot worm hole through an 1 3/4" thick piece of oak and drooled through.

It might be smarter to pour something like this in "lifts". Some type of epoxy that gels in an hour or two and pour in a 1/4 or 1/2" every three hours until full.

If you think education is expensive, try ignorance.

I never said tape stick was insufficient

John in NM

I don't know where you got that. I did say sometimes you get big leaks with rough wood, but the problem there is the rough wood, not lack of stick to the tape. The solution to that problem is to pre-surface the wood if you have enough thickness to be able to also re-surface after epoxying.

The point of mentioning the big leaks is to say "pay attention when filling", not to say "here is a problem that can be solved with just the right product that will aggravate other problems". There's too much theory and not enough experience in this thread already.

Duct tape will work of course, just as a lot of other tapes will basically work. The problem is that epoxy inevitably seeps between the layers of tape, making some of it hard to remove completely, and that tape is what you sand or plane off. With duct tape, you are more likely to have a stringy, sticky mess in the planer or on the sanding belt with the fiber reinforcing, and thicker and stickier adhesive. That is what I meant by way too sticky. Serves me right for making a brief reply.

Perhaps duct tape will be great. I never tried it because I always felt masking tape got everything just about right.

Fast is not always good...

John in NM

You want to have time for it to seep into all the little cracks. 2 hour West System was always about right. There are also always bubbles, and I would guess that the 24 hour stuff mitigates that some - more time for the bubble to move up to the surface. Don't know though, never tried that stuff.

I've used 5 minute urethane casting resin for other applications, but I wouldn't use it for this - not enough time. Anything under about 20 minutes and I don't expect you'll get enough penetration and you'll have more bubbles, either from the quick cure or from boiling in a big fill.

In many cases, letting in a similar piece of wood, as Barry says he'll try next time, is the better solution. But its a pain to get it to look good. I never liked doing it that way because I was at work - it took longer so the boss wasn't happy, and the boss always felt he could have done it better, so the boss wasn't happy. So the employee never formed the habit of trying it that way. When done well it looks great. Doing it well turns a ~2 hour fill into all day though.

Re: Epoxy observation....(OT?)

John b

Could you use a thin layer of 5 minute epoxy to to seal the bottom.

Re: Epoxy observation....(OT?)

Brian retired gunsmith from Colorado

In gunsmithing we often used modeling clay to create dams and or shaping items.

Re: Epoxy observation....(OT?)

Keith L Newton

Have you tried thickening the epoxy? Is there some reason not to?

I don't know if all epoxy is the same, but some I've used say that you can apply new over partially cured and still achieve a good bond between without any other surface prep. However I would check with the brand's user's guide to be sure.

Re: Epoxy observation....(OT?)

Brian retired gunsmith from Colorado

From gunsmithing supply company Brownells there are several formulae for epoxy. The two that I use most are the original Acraglas that I call "runny" acraglas as it is like maple syrup and is a 4 to 1 mix, I use it for repairs as it is thin, it penetrates and is exothermic. The second form is a 1 to 1 mix, called Acraglas Gel, that has a consistency of peanut butter. Thick and basically stays where you put it. This epoxy can be pushed into openings. Not as "penetrating" as the runny acraglas.

Acraglas is a Brownells trademark.