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EPOXY concerns ?
Courtney Thomas wrote:
Paul Oman wrote: Courtney Thomas wrote: Dave W wrote: They are different formulations. Follow mfgr. ratio data exactly. This is not a place for experiments! Dave Thank you. I can see I failed to adequately state my concern :-) Chemically, what is the difference in the resins when using the different formulations that require different amounts of hardener ? If only the viscosities are different, how are these different formulations attained ? Also, what is the difference in the hardeners, if any ? Is there a known website that fully delves into this without bias ? Thank you, Courtney ---------------- Hi Courtney There are about three different epoxy resins (bis A, F, and novolac). Just about everyone uses Bis A.... There are about 60 different curing agents that can be used. So.... most epoxies are, or can be, a blend of different curing agents. On top of that there are thinks like nonyl ... that can be added to part A or B to even out the mix ratios, lower the price, change visc. etc. The curing agents are a lot more expensive than the resins so forumulating an epoxy with with a 4 to 1 or so mix ratio (instead of a 1 to 1 or 2 to 1 ratio) saves the formulator $$ (or increases their profits) paul oman - progressive epoxy polymers, Inc. --------------------------------------------------------------- Thank you Paul. What's the difference between bis, A, F and novolac ? ********* Bis A resins are the most common. Bis F and especially novolac provide much better chemical (an a bit more chemical resistance. What do the 'curing agents' actually do ? Catalyze the polymerization ? ******** they are the other half the the equation needed for the reaction to happen the forms the complete epoxy Is the reason that everyone doesn't use the same 'hardener', because different ones lend a different character to the curing process, otherwise, the same end product... results ? ******* yes pretty much the same end result, but yes different ones do have dif properties (cure rates, times, blushing properties, etc. Suspect $$$ is the controlling factor for some epoxy manufacturers. So, is the bottom line that....if you can find a 1:1 or 2:1 mix that will satisfy your needs, that's the best way to go and the more exotic formulations are also more circumscribed in terms of usage hence more likely to be inappropriately applied, such as low temp applications, etc., that ultimately don't properly cure due to a flawed application process, hence fail ? ******* in a marine setting they pretty much all will work. Boatbuilding, marine applications, etc. are not very demanding for epoxies, hence there are lots of them out their (we think ours in one of the best!) Would this be just one more example of vendors bamboozling customers with attempts at masking a generic product with proprietary 'technology', witness the auto manufacturers and their glomming onto electronics, or do some actually have worthwhile differences and related costs and PERFORMANCE, that justify their claims and charges ? ****** lots of ways to make an apple pie. It's all apple pie but we all have favorites (and some like it with raisins). Yes, most if it is very overpriced. Any online references that address this ? ****** yes, but afraid they are all written and posted by me! paul oman - progressive epoxy polymers Appreciatively, Courtney -- "Living on Earth is expensive, but it does include a free trip around the Sun every year." ============================================ PAUL OMAN Progressive Epoxy Polymers, Inc. Frog Pond Hollow - 48 Wildwood Drive Pittsfield NH 03263 10:30-3:30 Monday-Thur EST 603-435-7199 VISA/MC/Discover/Paypal http://www.epoxyproducts.com ============================================ |
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