Tom & Shelly's build

[tony.latham]

I've gone through about four gallons of Raka with the pumps and have not had a problem.

You've probably figured this out but it's important to mix small batches. Maybe a half cup at a time. Or it'll "go off" in the pot. (I buy a volume of disposable cups for epoxy work.)

Tony

[KCStudly]

If you dig into the tech info on West System's website the design spec for the ratio is actually by weight; they just convert it to volume because that is how most people want to do it, as it seems easier. I like the precision and added assurance of using the scale to get it exact (although there is a small acceptable range that is specified in that same literature).

As to using a respirator, it really shouldn't be negotiable. If the fumes don't get you, the next thing you are going to be doing is cutting off excess fringe, sanding bumps and seams, roughing up surfaces for mechanical bonds, etc. I would not take a project of this scale on and attempt to rely on those cheesy disposable paper dust masks. For $32 dollars you can get a proper half mask with vapor cartridges that you won't mind wearing for long periods at a time, and it will last past this project and beyond. My lungs are worth way more than that. Learn how to disassemble and clean it regularly; let it dry and keep it in a sealed zip lock bag when not in use. For best results keep a clean shave, or at least make sure facial hair is contained; you don't want hair breaking the sealing bead around your cheeks and chin.

[Tom&Shelly]

I've gone through about four gallons of Raka with the pumps and have not had a problem.

You've probably figured this out but it's important to mix small batches. Maybe a half cup at a time. Or it'll "go off" in the pot. (I buy a volume of disposable cups for epoxy work.)

Tony

Yes, our friends who used Raka epoxy to build a boat tell us it's best to have one person mixing while the other applies the product.

We'll start with small batches and see how we want to modify our technique.

Tom

[Tom&Shelly]

If you dig into the tech info on West System's website the design spec for the ratio is actually by weight; they just convert it to volume because that is how most people want to do it, as it seems easier. I like the precision and added assurance of using the scale to get it exact (although there is a small acceptable range that is specified in that same literature).

As to using a respirator, it really shouldn't be negotiable. If the fumes don't get you, the next thing you are going to be doing is cutting off excess fringe, sanding bumps and seams, roughing up surfaces for mechanical bonds, etc. I would not take a project of this scale on and attempt to rely on those cheesy disposable paper dust masks. For $32 dollars you can get a proper half mask with vapor cartridges that you won't mind wearing for long periods at a time, and it will last past this project and beyond. My lungs are worth way more than that. Learn how to disassemble and clean it regularly; let it dry and keep it in a sealed zip lock bag when not in use. For best results keep a clean shave, or at least make sure facial hair is contained; you don't want hair breaking the sealing bead around your cheeks and chin.

Well sure, but can we modify the respirator by drilling a hole with the same diameter as a cigarette so we can smoke while applying the epoxy? Just kidding!

(Shelly says I should have responded with "but I can't convince my wife to shave")

It's a good point. We need something better than those paper things for dust protection.

Thanks KC.

Tom

[Tom&Shelly]

OK, so some more questions about epoxy/fiberglass. If anyone has any insight, I'll appreciate your thoughts.

We're probably going to go with Raka 350/127. I couldn't find a coverage estimate on their site, but for West Systems it seems to be roughly 100 sq feet per quart of resin per coat. Obviously lots of variables in there, but if that's generally correct, I estimate maybe 9 quarts of resin for the whole teardrop. Am I off by an order of magnitude, or anything?

I'm thinking it will take about 12 yards of 60" wide fiberglass to do the walls and roof. I now plan to go with 4 oz fabric, to make the wall/roof transition easier.

We are thinking of adding pigment so our floor in the galley and sleeping compartment is gray. Does anyone have any idea how much of Raka's pigment per quantity of resin it takes to make an opaque gray floor? (If no one knows here, I'll probably call Raka tomorrow.)

Similarly, if I want to make a paste to fill cracks in the A side of plywood prior to fiberglassing, does anyone have any insight into how much silica and/or micro-balloons I will need per quantity of resin?

Obviously, we will experiment before applying to the project (and I'll report results here). We won't ruin the teardrop (at least not that way), but it would be nice to have an idea of quantities needed to order.

I will also order pumps. Think for our first tries, we will use the calibrated cups, but will use the pumps to mitigate waste and mess. And we will definitely buy respirators for sanding, and will try the correct cartridges and use them for applying the epoxy.

Thanks everyone for all your help!

Tom

[KCStudly]

I had no trouble at all wrapping 4 to 6 inches of 6oz over the 3/4 radius of my cabin profile. The front radius of my roof profile is 13-1/2 inch.

Tony, I guess I get hung up on all of the reports by people who used epoxy on their bent roof plywood, w/o glass, and then suffered failure when the grain split open and water got in. Yours is the voice of experience, for sure.

I must be on my 3rd (maybe 4th) gallon of epoxy. I stopped buying quarts after about the 3rd or forth one; which came at about the same time there was a price increase. The gallons became much more economical, especially when factoring in the extra trips to the supply store.

My cabin is 9'-8" long, 64" wide and a tad over 4ft tall. I have applied two plies of 6oz most everywhere, roof, hatch, side walls, front wall, tongue box and wrapped under edges of the floor about 6 inches (before I am done I may still change my mind and do the whole underside of the floor). I must have at least 25 yards of 60 inch wide in it so far. Fortunately I can buy it locally; have had to make a few trips to resupply, plus had a few yards donated to me. I would start by buying at least 1 gal of epoxy right off the bat, but don't over stock because it does have a shelf life.

You will need more fairing filler than you think if you are going to use it to fill the cloth weave, especially if attempting to do it on vertical surfaces (they require thicker mixes to avoid sloughing off). After going through a few of the smaller canisters of the 410 I stepped up and bought the big can. Spraying a high build primer is another option.

I have used less of the bonding/filleting filler, maybe two small cans. I used PLP construction adhesive, not epoxy, for my wall and bulkhead to floor bonding; if I had used thickened epoxy for these joints I suppose it would have been more.

[KCStudly]

Let me just say again that I am building a foamie. My fiberglass is my only outer skin, hence the two plies. Your mileage may vary.

[tony.latham]

Tony, I guess I get hung up on all of the reports by people who used epoxy on their bent roof plywood, w/o glass,...

That's because they are not using 1/8" Baltic birch bent with the grain.

Tony

[Carl01234]

I have been emailing Raka and and my 10*x5 benroy it will take 17 square yards of cloth and estimated 2.1 gallons with 4 oz cloth to get 3 coats. I am ordering the 3 gallon kit. This is for my exterior side walls and roof only. I did the bottom in regular polyester because it was available at home depot. But I hate working with that stuff.

[Tom&Shelly]

I have been emailing Raka and and my 10*x5 benroy it will take 17 square yards of cloth and estimated 2.1 gallons with 4 oz cloth to get 3 coats. I am ordering the 3 gallon kit. This is for my exterior side walls and roof only. I did the bottom in regular polyester because it was available at home depot. But I hate working with that stuff.

Thanks Carl, your numbers are close to mine (also a 10 x 5 Benroy). The fiberglass comes in 60" widths, so we are ordering 15 yards to cover the sides and roof without seams.

Tom

[Tom&Shelly]

Okay, we just ordered the 3 gallon epoxy kit and 15 yards of fiberglass from Raka. Decided it was easier to buy the 16 oz bottle of gray pigment, rather than call and ask how much is appropriate. We also bought a 2 oz bottle of black pigment, in case we want to darken it. We will experiment.

We also bought fumed silica and phenolic micro balloons to experiment with making a filler for cracks in our (wonderful) ACX plywood.

We are off to buy the baltic birch this morning. $12.83 a sheet, about a dollar more than it was in May. Still a good deal.

I have to order our doors and cargo doors from Challenger. May hold things up a bit waiting on these, but we weren't certain what sizes we wanted. Oh well, plenty to do in the meantime.

Tom

[Esteban]

Doesn't anyone make a Kevlar add-in for their epoxy systems?

Yes: www.uscomposites.com sells KEVLAR fabric, carbon/KEVLAR fabric as well as fiberglass fabric, carbon fiber fabric, epoxy, tools, and many other useful fiberglassing supplies.

I purchased discounted carbon fiber fabric from USComposits to use for building a teardrop trailer. I'll skin the side walls and roof with 1/8" Baltic Birch plywood protected (skinned) with carbon fiber cloth and epoxy, protected from UV light damage by marine paint, for light weight strength and long term durability.

The carbon fiber cloth is a splurge compared to fiberglass cloth. It's cost competitive with an aluminum skin. It'll weight much less (~85% to 90% less) than an aluminum skin, provide excellent water proofing, and frees me/you up to build dimensions unrestrained by the readily available sizes of aluminum sheets.

[Tom&Shelly]

Bought our Baltic birch this morning. Not sure it's really worth a picture, but I screwed the 5 foot 2 x 4s from clamping the floor together to the base of our Harbor Fright trailer so the 5 foot wide plywood just cleared the fenders. This is actually close to what I first had in mind for a teardrop. Somehow, the project grew....

[KCStudly]

Bringing plywood home is a big milestone, and the effort is worth noting.

Keep on keeping on!

[Esteban]

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