Raka Epox, comments and questions

[Tom&Shelly]

So I finally cracked open the bottles of 127 resin and 350 hardener and mixed a test batch. Used the beer cup method: first measured out 2 oz, then 4 oz of water into an inner cup, while marking the fill lines on the outer cup; then replaced the inner cup of water with a clean one and poured the hardener (2 oz) and then the resin (4 oz) to the lines.

Several lessons learned: 1. Don't forget the inner cup , and 2. Don't overfill past the lines. I did both with the hardener, which, I confess, I then committed a cardinal sin of 1st year chemistry students, and poured the excess back into the gallon bottle of hardener. Oh well, it wasn't too contaminated with dirt or water and hadn't seen the resin yet. I was more careful and got what I believe is a good mix.

I stirred for less than a minute, and it seemed to work well, but I will discipline myself to stir for several minutes from now on, now that I'm more confident in the working time. Honestly though, the stuff is so viscous I think it mixed well.

I also wore latex gloves and goggles, but no mask, though I left the door open. The slight smell didn't bother me. Later, when I will use it to lay up fiberglass, I'll wear the mask for sanding. I will also admit that after applying the epoxy and taking off the gloves, I got a little on the hands. I'm not worried and don't think I'll develop an allergy, based mainly on being way too careless with 5 minute epoxy since I was a kid. I've even used that stuff to repair partially missing finger nails and never had a problem. OK, don't anyone try that!

Applied some to the scrap ply, by pouring a small amount onto the surface, and then spreading with a white sponge roller:



Very satisfactory finish! I had a foam brush to tip off, but didn't see any bubbles, so I don't think it was necessary.

Then I realized that the 6 oz I'd mixed goes very far, and so I grabbed another scrap and tried applying it with the foam brush. Never heard anyone recommend that method, and now I know why:



Very thick and uneven. Wish now I had a third scrap and tried applying with an old credit card, but really, the roller seemed to work well for me.

So I left the rest in the "pot". 18 minutes after I began stirring, it was still a clear liquid, room temperature (mid 70's) and highly viscous, but at 26 minutes the top of the mixture started to turn yellow (which I hadn't heard about before and so didn't expect), and it began to heat up (which I did hear about and did expect). A few minutes later is was a uniform yellow, and seemed to be "green cured". I could dent it with a stirring stick. It stayed warm for about an hour. I wonder whether the yellow tint is just part of the curing process, or did the epoxy pick up something from the plastic cup?



However, the epoxy that was spread on the boards, being less concentrated than that in the cup, was still very soft. That is what I expected, based on what folks here have said, and what I read from Raka and other epoxy vendors. I have confidence the epoxy on the boards will cure, based on what happened in the cup.

So, before working with fiberglassing the sides of my teardrop, I plan to put several coats of epoxy (without fiberglass) on the floor. One question is how long to wait between coats. I do want the first coat to green cure, and Raka says I should be able to get a chemical bond for up to about a day after applying the first coat. Does anyone have experience with this and would you comment please?

For the bottom of the floor, I'm thinking about two coats, leaving about a half inch on the sides uncoated, so that later, when I glue the sides on (which will have 3/4 inch deep dados) the PL Premium will make contact with bare wood. I figure the 1/4 inch of epoxy into the dados will help protect against water getting into any minuscule gaps? Any thoughts?

For the top of the floor, I'm thinking a base coat of epoxy, then epoxy mixed with filler in a few defects in the wood. I have some silica and some phenolic, and wonder if a 50/50 mix would be appropriate? I then plan to let that fully cure and sand the filler smooth, then fine sand the entire surface to obtain a good mechanical bond. Then, I plan to mix some epoxy with grey pigment and coat the whole thing. (I'll also leave a half inch of the sides uncoated for better gluing to the walls.) I'm hoping the grey will hide the ACX plywood while offering a tough floor. We will later paint the portion of the floor exposed to sunlight in the galley.

To deal with my problems accurately pouring into the beer cups, I'm thinking of using pumps. I'll still use the lines in the cups to determine amounts, rather than relying on the accuracy of the pumps. So, what do I do with the pumps after that? Can I simply leave them in the gallon jugs and will they and the remainder of the products be usable in, say, 6 months?

I know a lot of you have lots of experience, and am interested in your thoughts. Thank you!

Tom

[pchast]

Tom, I was told plain white vinegar will remove epoxy before its set... It seems it
stops the reaction by changing the ph of the epoxy.... I used it once when careless
with West System epoxy, with good result.

[noseoil]

Only thing I would say is to make sure it's mixed thoroughly once it's combined, as you already noted. It's one of the biggest problems with epoxy & gets blamed for all sorts of difficulties later on. I always stir briskly for at least 2 full minutes, no matter how small the batch is...

[tony.latham]

I do want the first coat to green cure, and Raka says I should be able to get a chemical bond for up to about a day after applying the first coat. Does anyone have experience with this and would you comment please?

Yes, that'll work fine. (And yes, I have worked with epoxy for years.)

I stirred for less than a minute,

You need to mix it very well. For under, a minute might not be long enough.

For the top of the floor, I'm thinking a base coat of epoxy, then epoxy mixed with filler in a few defects in the wood.

I polyurethane interior floors––except for the galley which I epoxy. (But whatever finish you use, tape off where your walls will sit so you get good glue adhesion.)

I'm thinking of using pumps.

I've gone through several gallons of Raka using the pumps and have not had a problem. I leave the pumps in the jugs.



Tony

[Tom&Shelly]

Thank you all for your comments.

Thanks Tony. For the work described in our build thread, Shelly poured the epoxy and used a timer to stir for two minutes. (Three batches for the first coat, two for the 2nd on the underside of our floor.) Whatever other problems we had, we seem to have had very good ratios and good mixes. However, I did buy several pumps from Raka, so I think I'll try using them in the bottles, but still use the marked beer glasses for amounts.

And applying the 2nd coat about 20 hours after the first seemed to go on with good adhesion, despite the first coat being dry to the touch.

I'm feeling a little better than I did yesterday about the result, and will comment more in our thread: http://www.tnttt.com/viewtopic.php?f=50&t=70278&start=75

Thanks again guys!

Tom