Greg Luckett Posted March 25, 2006 Author Posted March 25, 2006 Pipefitter, How low does it need to get when you call a postponement? I don't do anything but filleting below about 45 or 50, and nothing when 32 or below, unless I can heat the shop. I have been out of K1 kerosene for about a month now, but have located a new source and restocked yesterday. Time to start building the details again. As soon as the weather improves enough I will finish out the Laguna 24, and then get my Spindrift built. The flowers are sprouting and the trees are starting to bud here.....I will be putting in 80 to 100 hour weeks for a couple of months getting everybody and thing ready to splash. Quote
JeffM Posted March 25, 2006 Posted March 25, 2006 By the way, though I have no experience with comparing brands, I believe most epoxies are solvent-free ("100% solids" as RAKA phrases it). They explain that including solvents leads to shrinkage as the epoxy cures and the solvent evaporates. Also, I was surprised to discover that my RAKA would cure at temperatures below those advertised -- if you were patient. It wasn't curing temperature that finally put me out of the outdoor epoxying business last fall -- it was the increased viscosity that comes with lower temperature: The stuff gets so thick that it takes 2 or 3 times as much to coat, and then slooowwly runs all over the place after you think you've put it to bed! Also, besides the slow and fast hardeners RAKA stocks, they also have a cool weather (pricier) one that really does set well at lower temperatures but has a longer pot life than the fast stuff. Quote
PAR Posted March 26, 2006 Posted March 26, 2006 The epoxy resin we use is "diglycidol ether of bisphenyl A". The "A" stands for acetone, the "bis" means two and phenyl means phenol groups. Bisphenyl A is a chemical made by mixing two phenols with one acetone. Bisphenyl A has the unreacted acetone and phenol stripped, which then is reacted with stuff called epicholorohydrin (say that three times real fast) The resulting reaction bonds these two glycidol groups on the butt of the bisphenyl A molecule. It's this goo that gets modified by each manufacture to provide specific properties. These are glycidol groups and they need a hardener, typically polyamines. Most of the time, these are organic molecules having more them two amine groups. Amine groups are quite alkaline (many folks react strongly to very alkaline materials) and are very similar to ammonia in molecular structure (also why they have the strong smell, especially in enclosed spaces) These reactive amine groups are nitrogen atoms with a couple of hydrogen atoms bonded on. These hydrogen atoms (in the hardener) react with the oxygen in the glycidol groups (resin) and form the final product, a cured thermoset plastic. The chemical reaction that takes place when the hardener is added to the resin, doesn't out gas solvents, though many may have been used during their manufacture. The hardener becomes part of the resin and forms the final product. Nothing leaves the completely mixed "matrix" during or after the cure. This is quite different then the polyester type of thermoset plastics which uses a catalyst. A catalyst starts the chemical reaction process, but doesn't become part of the product. This is one of the reasons epoxy is so much better then polys. Some manufactures have started to offer, slower reactive types of hardeners. These are typically the no blush types. They're starting to play with the hardener make up to keep the reaction temperature lower by spreading out the cure, so a side benefit is longer working times. The bottom lines are: certain manufactures produce a product that is more or less reactive to some people. So, you're only choice (if particularly sensitive) is to try different epoxy brands, especially those that have been formulated to be "less reactive". As to low and high temperature cures, there are many offering from the major producers, each seems to have different rates, but all within a similar range, without resorting to custom made goo (like I have to, here in Florida summers) If you do an epoxy search on line, there will be several manufactures pop up that you've never head of, but offer products that are just as good (in many cases better) than the major suppliers. If you do a lot of epoxy work, or expect to do so in the future, you'd be well advised to get some "starter" kits or samples and their booklets. Epoxy can be a big expense on a tape and seam construction, so doing the homework is a pretty good idea. I know people that love West, others that hate it, some that swear by MAS, System 3, even Glen-L's goo (which is just relabeled stuff from some one else BTW) most are happy to send you a "help me to decide to by your product kit" many web sites offer side by side comparisons (with a spin of course) For those of you (Oyster pay attention) that are especially sensitized take a look at Progressive's goo >www.epoxyproducts.com< Quote
Pipefitter Posted March 26, 2006 Posted March 26, 2006 When I first started looking into building a composite boat,Progressive's site was most helpful. Anything and everything about epoxy there. Including his trials with the penetrating epoxy sealer. The owner is most helpful. Wish there was a distributor here. Quote
Greg Luckett Posted April 23, 2006 Author Posted April 23, 2006 When I first started looking into building a composite boat' date='Progressive's site was most helpful. Anything and everything about epoxy there. Including his trials with the penetrating epoxy sealer. The owner is most helpful. Wish there was a distributor here.[/quote']Do you happen to have a link to his site? The penetrating epoxy sealer sparks my interest. Thanks. Quote
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