cleaning off amine blush (epoxy)

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JohnCoker

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Amine blush (formed as epoxy cures) is best cleaned with soap and warm water, but for paper tubes that's not ideal. Are there other options for surfaces that aren't waterproof?

I assume this is a polar/non-polar thing. Are there perhaps wipes or something that are good to clean water-soluble residue?
 
"best" is questionable.....
Chemically, you want a Silane such as Silquiest's A-1100 to strip the blush.
 
"best" is questionable
Sure, I meant it needed to be cleaned with water, instead of other things we commonly use particularly alcohol.
Chemically, you want a Silane such as Silquiest's A-1100 to strip the blush.
Hmm, that might be a bit much for hobbyists; the MSDS says category 2 skin irritant.
silquest SDS.png
 
I've had success baking it off by placing the rocket in a car with windows up in the summer, not in direct sunlight. 90s outside - upwards of 140 degrees inside You could replicate using an oven I suppose.
 
I'd look at the cheapest brand of non-flushable baby wipes and see what it has for soap.
That's a good idea. Baby wipes might clean up amine blush, but unfortunately they seem to have a lot of other crap that would create a layer of different impurities:
https://gonewmommy.com/2017/11/08/baby-wipes/

What I was hoping for is someone with a chemistry background responding with something like: "soap and water" just means a polar solvent with a surfactant; you can use any cleaning product of type/brand X because they have the same effect without requiring washing with water.

I agree that wipes would be ideal to reduce the amount of liquid applied to the surfaces. I like the Lysol wipes for cleaning up BP residue and motor cases, but here I want the surface to be really clean so that further bonding works well and I think all the standard cleaning products have a bunch of other crap in them that might interfere.
 
That's a good idea. Baby wipes might clean up amine blush, but unfortunately they seem to have a lot of other crap that would create a layer of different impurities:
https://gonewmommy.com/2017/11/08/baby-wipes/

What I was hoping for is someone with a chemistry background responding with something like: "soap and water" just means a polar solvent with a surfactant; you can use any cleaning product of type/brand X because they have the same effect without requiring washing with water.

I agree that wipes would be ideal to reduce the amount of liquid applied to the surfaces. I like the Lysol wipes for cleaning up BP residue and motor cases, but here I want the surface to be really clean so that further bonding works well and I think all the standard cleaning products have a bunch of other crap in them that might interfere.

Check out West Systems documentations. These guys know epoxy.
 
I would try repeated careful wiping with slightly-damp (not wet) paper towels. It would take a lot longer than washing, but the stuff is water-soluble, so it should still come off. That may not be practical in some cases.

I'm pretty sure that most baby wipes contain a fair amount of water, plus surfactants and fragrances.
 
This article, from a maker of epoxy flooring, may be helpful, as it states:

The recommended solution is removal using either denatured alcohol or a vinegar wipe followed by a clean water wipe or rinse.

So good old Ethanol, perhaps? (Obviously you need high purity...).

Ethanol is more polar than Isopropanol/Isopropyl.

Methanol is even more polar than Ethanol - so perhaps you could get some Heet from Walmart or an auto parts store and try that as well.

There’s also the issue of protic vs aprotic solvents. For example, methanol is protic and polar. Acetone is aprotic and polar.

Definitely steer clear of the horse lineament. (Dimethylsulfoxide). That stuff will quickly destroy epoxy — there are papers about using it to make recycling printed circuit boards easier by eating the epoxy.
 
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400 grit???

Sounds kind of like removing peanut butter with sandpaper. I guess you could do it, but at some point, you’re gonna think “there’s got to be a better way.”

More importantly, sandpaper will push the amine blush deeper into the cracks made when the sandpaper cuts into the epoxy. You can make the amine layer thinner, but to remove it, you need a solvent.

Oddly enough, it reminds me of changing my son’s diaper: no matter how much I dry wipe my hands, they smell of poo. Water and soap are required to get the smell completely off.

I’ve never tried alcohol for cleaning off poop though...
 
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I live in the South. Fall and winter can have issues.[had them when living in Ohio too]
High humidity 80%ish and when afternoon sun gets cool/cold quick 50ish. Which is early afternoon 3-4 O'clock.
Blush like these conditions.
Object get moisture from air condensing on them in garage or work area. [unless climate controlled.]
You don't see it, but its there.

In any case, to remove/PREVENT blush:
You can keep work light/s near object epoxied to prevent blush with heat, or remove blush usually with plain warm water or add a just a drop or 2 soap, to cup of water.

I just use Windex mostly for ease, and wipe with acetone when ready to re-epoxy or paint.
If you are experiencing blush in climate controlled rooms I have no idea. Never did myself.
PS I did build small glass boats in my youth and repair big ones.
..................................................................................................................................................
By the way it usually happens when the dew point is within 7-9 degrees of ambient temp. Same for when you spay paint used same condition, your reds, oranges,blacks will "haze" look 'cloudy" or "blush" the worst.
The aerosol paint mist picks up moisture from saturated air.
Also settles on wet epoxy causing blush.
Just check weather like on Windy for dew points. Can be a toasty 75-85 out but if 85-90% humidity your in trouble. Or 50-60 with 50% humididty..trouble .
So there is the science. I had to check daily for years when doing commercial work.
If conditions are right can happen just about anywhere in US.

Disclaimer: my numbers may not be perfectly accurate, just what my parameters are, based on past reading/ research and experience in field.
 
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As to specific use on paper issue.
Not sure I understand ,if tube is coated with epoxy, mist of water should not hurt it. Or if removing from fillets, caution with folded paper towel moistened should do the trick.
Blush is on epoxy, not paper correct? Bit of care when applying would do the trick.

Put work light about foot or so from object when gluing, just keep nice and warm to prevent. If ya got one cure in hot box.
 
As to specific use on paper issue.
Or if removing from fillets, caution with folded paper towel moistened should do the trick.
Yeah, the specific case I'm thinking of here is fillets between paper body tube and plywood fins. One would like to minimize the amount of water used, but still remove the blush for a subsequent bonding operation.

Most of the boat building and flooring articles about removing blush say to use soap and water, which makes sense for sealed surfaces. I guess I'll continue to use wipes and moist towels as I have in the past.
 
Vinegar is also easy to get and safe to work with.

For you, maybe. Unfortunately, I have to wear a respirator when I’m exposed to relatively small amounts of vinegar.

Sensitization is no joke, and (ironically enough) vinegar is something my lungs appear have become sensitized to. Which sucks, as Ketchup & BBQ Sauce can send me into a coughing fit...

I really appreciate your videos mention you wear a respirator, and encourage others to as well.
 
It is not clear to me in your first post, but are you just making fillets out of it or are you using it as a surface coat for the paper tube?
Only for fillets and general bonding.

I've not used unreinforced epoxy as a surface coating.
 
Only for fillets and general bonding.

I've not used unreinforced epoxy as a surface coating.

You might want to brush a thin coat of epoxy on the tube & let it ser you. Use some thin CA to coat the inside of the tube at both ends, maybe 1/2" to make it waterproof and then take the amine blush off of everything.
 
It sounds like there are ways to reduce amine blush, which occurs more with slow-curing hardeners in the presence of moisture. Likely vacuum infusion and/or high-temperature curing would help.

This page has some good info:
https://www.epotek.com/site/files/Techtips/pdfs/techtips_28.pdf

All the articles I've read suggest cleaning with soap and warm water. That's fine for composite parts, but obviously problematic for paper tubes and plywood parts.
 
All the articles I've read suggest cleaning with soap and warm water. That's fine for composite parts, but obviously problematic for paper tubes and plywood parts.

Hi John,

why not a soap+water mix, wet your favorite wipe towels, give a few wipes on the surface? That way, no running water on the cardboard tubes etc.

Definitely no sandpaper, that just makes it worse.

But I gotta ask, why the attention to cosmetics here, is the epoxy the final finished surface? Are you going to paint the rocket?
 
I live in the South. Fall and winter can have issues.[had them when living in Ohio too]
High humidity 80%ish and when afternoon sun gets cool/cold quick 50ish. Which is early afternoon 3-4 O'clock.
Blush like these conditions.
Object get moisture from air condensing on them in garage or work area. [unless climate controlled.]
You don't see it, but its there.

In any case, to remove/PREVENT blush:
You can keep work light/s near object epoxied to prevent blush with heat, or remove blush usually with plain warm water or add a just a drop or 2 soap, to cup of water.

I just use Windex mostly for ease, and wipe with acetone when ready to re-epoxy or paint.
If you are experiencing blush in climate controlled rooms I have no idea. Never did myself.
PS I did build small glass boats in my youth and repair big ones.
..................................................................................................................................................
By the way it usually happens when the dew point is within 7-9 degrees of ambient temp. Same for when you spay paint used same condition, your reds, oranges,blacks will "haze" look 'cloudy" or "blush" the worst.
The aerosol paint mist picks up moisture from saturated air.
Also settles on wet epoxy causing blush.
Just check weather like on Windy for dew points. Can be a toasty 75-85 out but if 85-90% humidity your in trouble. Or 50-60 with 50% humididty..trouble .
So there is the science. I had to check daily for years when doing commercial work.
If conditions are right can happen just about anywhere in US.

Disclaimer: my numbers may not be perfectly accurate, just what my parameters are, based on past reading/ research and experience in field.
I tried your windex recommendation on a payload section I did and so far it has worked well in removing the blushing, where denatured alcohol did not. Thanks for sharing!
 
But I gotta ask, why the attention to cosmetics here, is the epoxy the final finished surface? Are you going to paint the rocket?
In this case, this is not the final bond so I didn't want the amine blush to interfere with the later epoxy bonds. I've actually never noticed a problem, but I'm always on the lookout for ways to improve my techniques.
 
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