Thread: Epoxy Questions
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Old 04-30-2010, 04:15 PM   #17
Delfin
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Epoxy Questions

Quote:
Marin wrote:

*
Delfin wrote:

I have used Smith's penetrating epoxy which is the same stuff as CPES, but found it was only regular epoxy mixed with MEK....
Not true, actually.* What CPES isn't is regular epoxy mixed with MEK.* If you do this, you end up with a very brittle filling since the MEK flashes off and you're left with the hard, brittle cured epoxy.* Also, since the MEK flashes off so fast it doesn't carry the epoxy very deep into the wood.** All standard epoxies, including WEST, are petroleum based, and thus cure very hard and brittle.* The resins in CPES are derived mostly from wood and when cured have a toughness and flexibility very*similar to wood.

I'm not sure how many gallons of MEK thinned epoxy I have squirted into rotten window sashing, footings, or painted on teak, spruce, port orchard cedar, but it would be a few.* The MEK does not 'flash', but carries the epoxy as far as reasonable into the wood.* If you use Balsa wood, like the manufacturers advertising their products do to demonstrate their products, or punky wood like I do in real life, you get great penetration.* The "organic" solvents in CPES that you say go over over a "longer period of time" have a name.* It is MEK.* Take a whiff of CPES, then take a whiff of MEK.* Besides losing 2% of your brain cells, your sniffer will tell you what the solvent in CPES is.* MEK is not acetone and goes off fairly slowly, which is why they use it for this purpose.*

Marin, you're quoting from the CPES advertisement when you say "epoxy dries hard and brittle."* Compared to thinned epoxy like CPES, which don't actually harden much, that might be true but it depends on the thickener you use.* Want 'wood like' epoxy?* Thicken with wood dust and plane it like wood.


-- Edited by Delfin on Friday 30th of April 2010 05:21:35 PM
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