Epoxy Info ?

Has anyone used the MAS line of epoxies, They claim to be a non blushing formula, Is this accurate? And are there any down sides or negitives to this charactoristic.

Being a novice, this sounds like less work. But I'm sure it comes at a price.


Thanks

Grady

 

Blush can ruin your day if you've not prepared for it. This said, I've had little difficulty with blush, but I'm an experienced epoxy user. There are several manufactures of non-blushing epoxy. To some, the prep savings is justifiable, but I don't see the need.

Basically it boils down to this, you have two types of bond available with epoxy, mechanical and a chemical. A chemical bond requires you apply fresh epoxy over not yet cured epoxy, which forms a chemical linkage with the underlying goo. No blush has formed yet, so it's a non-issue. A mechanical bond requires a tooth be provided, so the over coat of fresh epoxy will have something to grab. The only way to provide this (reliably) is to abate the surface, which removes the blush anyway, resulting in a non-issue again. So I don't bother with non-blushing formulations, except in topcoat applications, where a particularly clear finish is desired. In these situations, I use a topcoat specific epoxy formulation, so again it's a non-issue.

 

So, as I understand it, i'll be ok if I reapply within 48 hours with any epoxy. Is there one brand that stands out, with ease of applicatioin, mixing ratio, and cure rates.

There are so many on the market that I can't really pickout any one product, that appears to be different or excellent.

any recomandations will help.


Thanks

Grady

 

The West Sytem resin I use is 5:1 and the hardener can be chosen for a fast or slow catylization (when in doubt go with the slower cure rate).
The resin and hardener can be bought with pumps that measure proper proportions so that one need only count resin pumps against hardener pumps.
West has never failed to give good results. I generally abrade between layers unless working continuously. I like the viscosity of West too. On vertical joints, like I was doing today, I coated both surfaces (Glass hull and cedar sheer clamp lamination) and very little dripped before the part was clamped on. Very much like syrup.

 

Thanks Alan, I have seen their line at West Marine and have read quite alot of there user guides, but was just wondering if there was something I might be missing. And when using these products day in and day out you get to know them quite intimately. Finding the right product can make your life sooooo much easier.

I was also concerned with the wide range of mixing ratios, It seems like the formulation can differ extremely from one manufacture to the the next. And I don't really understand the need for such ratio difference.

I'm sure I'm over thinking this, but there are reasons for everything and just want to use a product that will not only perform well but have above average workability as well.

thanks for the info.

PS. I was leaning toward West Systems, because of their rep.

Thanks

Grady

 

Well, I'm not a big epoxy user like some, and there are, i'm sure many good formulations out there, some better for wetting out, others better for when more viscosity is desired, and then all the rest, already discussed.
But I've used the same West System 5:1 for twenty years, for every purpose, and so I can at least say that unless you are dealing with epoxy every day and doing lots of building and repairing using it, you don't have to worry about the absolute best epoxy for the job, just the best all around epoxy you are familiar with.

 

48 hours is way past the time limit to recoat without removing blush or abating the surface. The epoxy has to be in the "green" stage, which is still quite soft to accept an overcoat and have a chemical bond. Even the slowest curing epoxy will reach this stage in a few hours. Anything other then this, the epoxy needs to have some tooth for a mechanical bond.

It's hard to go wrong with the major brands of epoxy. MAS, West System, Raka, System 3, etc. each having very similar physical properties. There are some "less refined" products that can save you some money, but be warned, they can be more difficult to work with, having tight temperature ranges and faster cure rates.

When in doubt about blush, clean and sand the surface. If the epoxy has gone non-tacky and reasonably hard (difficult to dent with a finger nail) then you're past the chemical bond stage and should rely on a mechanical one.