No, it does not. When the chemical reaction (it doesn't "dry") takes place there is no mass lost. Here are the numbers from an experiment with FC wrap epoxy, measured carefully but with two different syringes of the same volume.

Pan with old hardened epoxy and a mixing stick: ..231 ounces

Plus 2 cc's of resin: .309 oz.

Plus 2 cc's of hardener: .399 oz.

2 minutes of mixing and let it set.

When hard: .399 ounces.

Weighed it many times in each condition, and it was consistent.

This is a very interesting discovery, Mick!

So, it seems epoxy is not like other types of materials that have a 'medium' that 'evaporates' or 'gasses-off' during the drying and curing process?

What your are suggesting is that nothing is leaving the mix reaction. All the material is remaining and combining into something new - hopefully a clear, hard, and tack-free substance.

This makes me think about the difference between "drying' and 'curing'. I can understand the difference though it may not make a difference.

I can imagine how 50-50 thread epoxies are formulated to combine because the ratio is essential to the result. Get too far outside the tolerances, and you will have excess molecules/atoms that are still 'free' - and make a tacky finish. I have read that Rod Bond can work just fine up to a 60-40 ratio. This is brilliant chemistry and marketing! Design for a healthy range of 'errors' to ensure consistent performance. Thread epoxy may have a more narrow margin for error.

Makes absolute sense why getting the epoxy mixture amounts right makes all the difference!

My non-chemist take.

I'm surprised that anyone thought that any 100% solids epoxy would lose weight once cured.

Ralph O'Quinn designed RodBond so that it would cure even at a 40:60 ratio (still recommended 1:1). Ralph knew that most would measure by eye so he allowed for such a wide variance in mix ratio. Not so with his (or others) epoxy thread wrap finishes which only have about a 5% window variance. On a 3cc total mix, even a couple drops off one way or the other can result in a finish that does not fully cure. On a total 6cc mix, those same one or two drops don't make as much difference.

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Well, I for am surprised there is not a minimal delta due to off-gassing or evaporation of some sort. As I am the dope who posed the theory, which Mick has proved was tomfoolery on my part. Liberal arts buy vs engineer. Bet with the engineer! I guess they have the formulas down after many years.

My comments were referring to common bonding epoxy used on the reel seat and not to thread epoxy, but that probably does not make a difference. I am not certain how similar or different their formulas are.

Thanks for testing, Mick.

"I'm surprised that anyone thought that any 100% solids epoxy would lose weight once cured."

I'm not surprised. We have seen the posts about epoxy drying, drying tents, drying motors, drying drying drying. If something dries it's logical that it would lose some weight. What so many don't seem to understand is that epoxy does not dry, it cures through a chemical reaction. In chemical reactions mass is not lost.

But this experiment shows it clearly.

Our epoxy adhesives and wrap coatings are comprised of 100% solids so there is nothing to evaporate. Yes I agree that the poor terminology used by many probably does lead to the making of incorrect assumptions.

One notable exception was the old Clemens Crystal Coat (KlassCoat) which although marketed as an epoxy was a 2-part system and did contain solvents.

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Please explain 100% solids. It's hard to visualize two bottles of clear liquids being "solids." thanks

It has to do with the percentage of solvents in the epoxy that won't evaporate. 100% solids epoxy doesn't have any solvent in it that could evaporate while curing.

David Baylor Wrote:
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> It has to do with the percentage of solvents in
> the epoxy that won't evaporate. 100% solids epoxy
> doesn't have any solvent in it that could
> evaporate while curing.


That's pretty much it. No evaporative solvents.

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Thank you, Tom.