How large of a epoxy batch?

[MichaelG]

How large for the first batch of epoxy resin (U.S. Composites) with medium hardner going on 7.5 oz. e-glass cloth on a 16' x 4' x 1/4" lauan boat bottom. I'm worried if I mix enough to do it all, that I won't finish job before the batch starts to set up. Do I have to do it all at once or can this be sectioned? (I would like to do it all at once.)

MichaelG

[Trevlyns]

A wise old fella at the boat yard just this morning told me "Always mix too little epoxy - you can always mix some more"

[alan white]

You can set up measured containers of epoxy and hardener, not yet mixed. These could make cups, pints, or quarts if mixed. Start with a quart. Have ready but not yet combined two more quarts and a couple pints and maybe a cup.
You need only mix the two parts and a minute later you have epoxy ready. If you don't need them, just pour them back into the original containers.

Alan

[PAR]

Work in small batches until you get comfortable with the process. After you mix the batch, spread it out in a thin film. Some folks like disposable paint tray liners for this, but I don't like the bumps and ridges on the bottom, so I use large Tupperware containers and lids. On large batches of epoxy the biggest Tupperware I have will be too deep, so I spread it out on a piece of plywood (precoated and sealed of course). You can roll or scrape up what you need and the goo stays reasonably thin, which doesn't permit heat build up. The Tupperware containers are easily cleaned after the goo has cured and my favorite plywood board I use for big jobs is belt sanded smooth before each use.

Whatever you do, don't let the mixed epoxy sit in a cup, as it will quickly build up heat and cure before you have a chance to apply it.

[MichaelG]

I'm listening, thanks for the advice
MichaelG

[Flumixt]

I've saved XS epoxy resin overnight in the refrigerator freezer a couple times. Or a couple hours if interupted by something important like my sweet wife. Versus tossing it seemed worth trying. (The resin - not the wife). On the other hand uh wife uh tossing uh well uh never mind.

Once saved some 2-part polyurethane paint 2-3 weeks. It was very stiff like taffy but a lot of brushing thinner brought it back. Used it on a hatch cover and it has stood up for 8 years now.

That particular freezer is at about 10º to 15º F.

[Moosemiester]

These are all very good ideas.

When I'm doing a big batch I pre-measure multiple cups of resin, so when I need more I only need to pump in the hardner, mix 'n go.

The trick with large pieces of cloth is to stay focused, and keep track of time; then you get a sense of exactly how many minutes it takes you to mix, how many minutes a pot, cup, or batch is lasting. An all news radio station is great, because most of them give you time time every two minutes, or one with lots of commercials because these are almost always 30 seconds each.

The biggest mistakes I made at first were:

Going too fast because I was worried about the epoxy setting up.

Not spending enough time mixing, because I was working too fast.

Trying to go back and touch up epoxy that had already set, or trying to pick out the ineveitable little fuzzballs of cloth fiber (sand 'em off later).

Going too fast. Did I say that already :-)

Big batches in a cup... a b s o l u t e l y!! Here's a guide:
If you're using U.S. Composites 635 medium 3:1 epoxy, if you make a batch larger than 12 pump strokes of resin, and 4 strokes of hardner, you'll want to take it out of the cup and pour it into a paint tray as the others suggest or your working time will be cut if it's much over 75 degrees.

Flumixit, a woman who lets you put uncured, smelly epoxy resin in the freezer with food is truly a sweet woman indeed!! Does she clean your pots for you, too?

[Flumixt]

Moose:
Its an old refer in the garage for our fruit tree XS in the summer. Nuthin in the freezer cept 2-liter bellywash bottles of ice. I try to seal the resin tight tho. 1964 Marquette. Bought it new. Ain't missed a beat all these years.

Not sure just what you mean by "cleaning my pots" - never heard it expressed quite that way before.

[Fanie]

If you weigh the material you use you may be able to make the batch up pretty close since there is a certain amount of epoxy you'd use per gram mat.
Also, try figuring a method out to quickly wet the mat in strips then roll it up as you wet, so that when you apply the wetted mat you simply roll it out on the surface and you can roller bubbles out.

[Moosemiester]

Flumixit
If you use the West System re-usable plastic mixing cups and mixing sticks, which I really like for small to medium sized jobs because I'm CHEAP...

There are so many "consumables" when working with fiberglass/epoxy, anything I can re-use is good.

But if you use the West Cups, or pots, there is the inevitable next day task of getting the hardened resin out, in order to use the cup & stick again -- hence "cleaning your pots"...

[Flumixt]

I believe you misunderstood my comeback. :-)

[PAR]

I use a pre marked, clear plastic cup, for each mixture I have. This cup sees no resin or hardener, but does serve as the guide for the disposable cup placed inside when I measure out the goo. Occasionally, I'll have to clean up some drips off the outside of the "measured" cups, but the cups used during a run are tossed. In other words I have cups marked for 3:1 hardener with graduations for different amounts (for example). I put another cup inside this and then dispense goo until I hit the mark I desire, where I then remove the measuring cup for the next batch.

Stand up the pre-measured resins and hardeners near the work and use them as necessary. If I have left over, it gets poured back into the can of respective goo. I never dispense goo when I'm in a epoxy run, I've got clamps, wetout and other things to worry about, let alone remembering if it was 5 pumps or 6, while the stick-um is kicking on the work.

Epoxy work is about procedure. Everyone works out a system, a procedure and the successful builders I've known all stick to it like, well epoxy, knowing full well what happen if they don't. The easiest way to screw up an epoxy job is to rush in without having you procedures in place.