How quickly does amine blush form?

[Sailorman Ed]

I fully understand that the amine blush comes to the surface but how quickly does this occur? I am in the process of adding filler / sanding coats with high loadings of 3M bubbles and the red micoballoons. Last weekend the conditions were perfect to quickly come back and add a second coat just as the first coat had set up enough. I did not sand nor wash down between coats. So I got to wondering how quickly the amine comes to the surface? Probably aless than 30 minutes between applications.

[paxfish]

I always keep a bottle of isopropyl alcohol handy and a bunch of rags. A quick wipe down evaporates quickly and off we go with the next bit of glass

[cruisersfarm]

The best answer, given your story above, is "not that fast."

Overnight or hours later, after it's kicked off, not 30 mins after application.

You are still in chemical bond territory 30 mins later and any time you can dent it with your fingernail.

Note: I've used a LOT of epoxy. So much I have an allergy.

[Sailorman Ed]

thanks Cruisersfarm - that is what I thought, dent with my fingernail. I usually apply a very thin coat of epoxy only before the highly loaded filler so being able to apply immediately, saves some epoxy.

I am getting much better at always wearing gloves and more careful about keeping the epoxy off me - I do not want to develop the allergy!! and wear the respirator when sanding.

[UNCIVILIZED]

Another method to avoid having to deal with the blush, is to use peel ply on your laminate. So thet if/when things have cured, you have a nice & clean, blush free surface to bond to.

Plus, with some digging, you can scare up some kinds of epoxy purpose designed not to blush.
Ditto on Bishphenol (sp?) free resins, which, when used, greatly lower your chances for becoming allergic to Epoxies.

[cruisersfarm]

Originally Posted by UNCIVILIZED

Another method to avoid having to deal with the blush, is to use peel ply on your laminate. So thet if/when things have cured, you have a nice & clean, blush free surface to bond to.

Plus, with some digging, you can scare up some kinds of epoxy purpose designed not to blush.
Ditto on Bishphenol (sp?) free resins, which, when used, greatly lower your chances for becoming allergic to Epoxies.

Actually, it's the amines in the hardener one becomes sensitive to. Nobody develops BPA allergies. BPA, while an endocrine disruptor for sure, is not a chemical humans become sensitized to. It lines all of our canned food, etc.

Peel ply is a good way to go, though i like the OPs method of wet on wet better. No secondary bonding. Strongest possible adhesion as the polymer chains extend fromthe new coat right into the earlier coat. Peel ply provides only a physical bond (assuming we are peeling the peel ply off cured epoxy for the next layer).

Definintely, definitely use blush free epoxy. System Three is a good one. There are several more.

[Zach]

If you call up west systems, they have in the past told me that up to 3-4 hours or so is the maximum working time they'd recommend without allowing a full cure and sanding because of blush. It'd be worth a call to see if that still holds true.

I normally work with either a thumb print, or finger nail test. If it leaves a finger nail, and is less than 2 hours or so I keep on going.

I'm also one that is sensitized to epoxy...

Just be aware that even with the real thin latex and nitrile gloves, you don't have but a few minutes with them before acetone drives stuff through the gloves. They keep you clean, but don't necessarily keep the nasties off your skin... Acetone penetrates them through diffusion pretty quickly!

Pour Acetone in a glove, roll up the end... 5 minutes or so they are paper thin. I like "Thickster" nitirile gloves, and then put on two or three pairs of the thin nitrile gloves on top, and change when they start to get gross when doing clean up.

Cheers,

Zach

[Dave Lochner]

Originally Posted by Zach

If you call up west systems, they have in the past told me that up to 3-4 hours or so is the maximum working time they'd recommend without allowing a full cure and sanding because of blush. It'd be worth a call to see if that still holds true.

I normally work with either a thumb print, or finger nail test. If it leaves a finger nail, and is less than 2 hours or so I keep on going.

I'm also one that is sensitized to epoxy...

Just be aware that even with the real thin latex and nitrile gloves, you don't have but a few minutes with them before acetone drives stuff through the gloves. They keep you clean, but don't necessarily keep the nasties off your skin... Acetone penetrates them through diffusion pretty quickly!

Pour Acetone in a glove, roll up the end... 5 minutes or so they are paper thin. I like "Thickster" nitirile gloves, and then put on two or three pairs of the thin nitrile gloves on top, and change when they start to get gross when doing clean up.

Cheers,

Zach

Distilled white vinegar, 70+% isopropyl alcohol, and denatured alcohol all work to clean up epoxy before it cures. Each of those are much kinder to the skin and don't destroy gloves as quickly.

[Rumlater]

What's the can say, I believe it 24 hrs, I have never had had a problem with another coat the next day

[Sailorman Ed]

What's the can say, I believe it 24 hrs

One bottle says Epoxy and the other says Hardener.

I have been using vinegar (apple vinegar also works) for years now, much, much better than acetone (nasty stuff - your skin absorbs it very quickly).

Another trick, after you use your brush, put another 3 squirts (depending on your brand) into the container, mush the brush around and it will be good the next day. Just remember to add hardener to it the next day. I keep a small container with a slot cut in the top for the brush handle.

One more - I stopped using the brush to spread unfilled epoxy onto large surfaces, now use a wide Bondo type spreader. Pour some on and spread it this way. Faster and more even coverage. Flex to remove from the spreader 1+ day later. The Bondo brand comes as a 4 pack.

[Lucky]

Originally Posted by Sailorman Ed

thanks Cruisersfarm - that is what I thought, dent with my fingernail. I usually apply a very thin coat of epoxy only before the highly loaded filler so being able to apply immediately, saves some epoxy.

I am getting much better at always wearing gloves and more careful about keeping the epoxy off me - I do not want to develop the allergy!! and wear the respirator when sanding.

Hi all,
Be exteamly carefull when using epoxy! I had a boatbuilding friend who suddenly died at 50. Everyone did not understand why he died and an autopsy was performed to try and reveal what caused his dead. It turned out that all hi internal organs failed due to epoxy poisening of some sort!

When working with epoxy always wear proper respiratory and body protection gear.

Happy lead free sailing from Lucky

[Terra Nova]

Originally Posted by Rumlater

What's the can say, I believe it 24 hrs, I have never had had a problem with another coat the next day

Very bad tech.

Re-coat before the curing develops; within a few hours should be OK. But be aware that ambient temperature affects cure time.

If you can't re-coat within a few hours, the blush must be removed with water, and the surface scuffed up.

[TeddyDiver]

There's no excact time. Temperature, air humidity and chemical properties of the epoxy all together contribute. From few hours to several days...

BR Teddy

[Olddave]

Originally Posted by paxfish

I always keep a bottle of isopropyl alcohol handy and a bunch of rags. A quick wipe down evaporates quickly and off we go with the next bit of glass

I have never heard of alcohol being used to remove Amine Blush. AB is water soluble, so is alcohol really removing it?

If it appears I just use water and a scotch brite as recommended by West System. Never had any problems.

I am very careful with the dust when it is less than a few days old. Got sensitised years ago and came up in welts. Better work practices has kept me good since then.

Dave

Dave.

[mawtty]

To avoid the toxic effects from the solvent, which I assume is the worst offender in epoxy work (correct me i am wrong);
I use vinegar to clean my hands and skin.
It is very effective, not expensive and soft on the skin.
I don't use it as a thinner.