​Amine blush removal, and epoxy choices?

[Guest]

I lightly rolled and tipped out some birch yesterday, using West 105 resin and 205 fast hardener. Two thin coats a couple hours apart, using a new can of hardener and fresh/calibration checked pumps, so I know the mix ratio was correct.

I have amine blush, which I have not had, at least to this extent in quite a while. Feels like I rubbed the pieces down with bacon grease.

I have been using mostly 206 slow hardener, so maybe that? It may have been the timing of the 2[SUP]nd[/SUP] epoxy coat (1[SUP]st[/SUP] coat just barely tacky), or the warmish and humid shop conditions. Or all three. I haven’t put the shop AC unit in the window for temp and humidity control; that may be a lesson learned.

Before I top coat with spar urethane I need to remove the blush. My usual amine blush removal has been to soapy water wash the surface, changing to clean, uncontaminated rags occasionally, and then alcohol wipe before doing any sanding and top coating.

That has worked, but it doesn’t hurt to ask. How do you remove amine blush?

And yeah, I know, some resins don’t blush, but I have West System pumps and spare pumps and spare-spare pumps, various hardeners and the gallon sized cans of resin. None of that stuff ever seems to run out at the same time, so I just buy a can of whatever I’m getting low on. I can’t bear the thought of amassing a whole nother shelf of resin, hardeners and pumps.

Which brings up a related question. If you had to pick one epoxy resin, hardeners and etc to start with in the shop which one would you choose? Or have chosen if you had known?

 

[memaquay]

System three clear coat for wet out and system three silver tip for fill.

 

[yellowcanoe]

I remember Bell Canoe amine blush. Back when the shop was subject to humidity

 

[Glenn MacGrady]

I remember Bell Canoe amine blush. Back when the shop was subject to humidity

I don't know if it's called amine blush years after the build is complete, but my 2002 Bell will still get milky white on the interior when exposed to standing water. Charlie Wilson says it's the resin they used at Bell. I can easily remove this residue with acetone, and a coating of Penetrol will prevent (for several months) recurrences of this blush.

 

[Guest]

After sanding, I've used Ammonia, it shouldn't leave residue like some soaps, but a thorough rinse, and either Acetone, or Paint thinner should do the trick. Your method should be fine however !

I have always removed the amine blush before sanding, and then cleaned again after.

Also note the hair dryer, I like to warm my epoxy a little while mixing, especially in cooler temps.

Alan weighs his batches

What other use would Alan have for a hair dryer.

I just haven't picked up a small scale yet.

I had no idea how often I would use a small weight scale in the shop until I picked one up. And the heavier weight hanging Taylor scale that Robin suggested a few years ago, also very handy.

 

[Chip]

Mike, that is the kind of question I ask you, which makes me think you are putting it up for a laugh. But I don't get it (not unusual). At any rate, amine blush is best removed with soap and water. I've used Dawn and I've used ammonia solutions and had success with both. I'd do it before sanding, since sanding might just grind it in and make it harder to remove.

 

[pblanc]

I have been happy with West System epoxy and have seldom had troubles with amine blush. I suspect in your case it was the humidity.

If I am applying another coat of epoxy or another layer of cloth over epoxy that is still green I do nothing. If I am applying something (paint, varnish, epoxy) over cured epoxy, I routinely do as you do, washing with soap and water (usually with Dawn dish washing detergent), scrubbing with a brush if need be, and rinsing well before wiping down with denatured alcohol.

 

[Guest]

Mike, that is the kind of question I ask you, which makes me think you are putting it up for a laugh. But I don't get it (not unusual). At any rate, amine blush is best removed with soap and water. I've used Dawn and I've used ammonia solutions and had success with both. I'd do it before sanding, since sanding might just grind it in and make it harder to remove.

I wasn’t going for a laugh, I sometimes don’t know what I don’t know and wondered if there were recommendations beyond soapy water.

Cut & pasted from West System:

Amine blush is water-soluble, so it’s very simple to clean away. All you need to do is reach for a plant spray container, some warm soapy water and a Scotch Brite pad. Spray the affected surface with the water, wash thoroughly using the pad, wipe dry with paper towels and you’re done. It’s that easy.
Try sanding an amine blush-covered surface and it will clog your sandpaper and cause the blush to penetrate your work more deeply.

I went a little above and beyond just that recommendation. I got a little bucket of soapy water and a handful of rags and used a fresh clean rag to wash each of the four pieces, then lightly Scotchbrighted them, then used a clean water rinse to get rid of any soap residue and paper towel dry.

Of course all of that could have been avoided if I had done one or more of the following:

Used the slow hardener. Per West System the fast hardener is more prone to amine blush.
Put the shop AC in so it was not so humid.
Used peel ply so the amine blush was on top of the ply.

So see, I’m still learning things.

 

[Jim Dodd]

Good research Mike !
Jim

 

[Guest]

Good research Mike !

I had read those West System amine blush recommendations before, but it never hurts to ask, and look again. I vaguely recall having read various pros and cons of using ammonia, vinegar, toluene, paint thinner, acetone or ect, but the opinions were sometimes mixed, especially when it came to leaving some incompatible residue or eating the epoxy.

Plain old soapy water worked fine, especially since I was careful to switch rags and not contaminate the water in the bucket. Hmmm, that’s probably why West suggests having the soapy water in a spray bottle.

And yeah, I sacrificed two fresh Scotchbrite pads, now relegated to dirtier shop work.

I did an alcohol and paper towel wipe after sanding in preparation for the urethane coat. And there I do have a shop spray bottle of alcohol always at the ready. An old, thoroughly rinsed 409 spray bottle, which has such a tight seal and positive-off nozzle that the alcohol doesn’t evaporate.

I final clean a lot of surface with alcohol, especially prior to a top coat. Dampen paper towels poured from the bottle was often oops-wayyyyyy-to-much-alcohol. Followed by “Crap, where did I put the screwcap for the alcohol bottle?”

And the little bottle of alcohol I poured into the 409 sprayer has lasted an incredibly long time. I think I need another shop spray bottle for soapy water always at the ready.

Yup, still learning things. That’s why I love working in the shop.