How to size and mix small quantities of epoxy primer, (or other multi part paints)

R

Rusty105

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So, like many here, I am finding myself prepping small sections at a time and wanting to paint them with an initial two coats of Epoxy Primer. but a lot of times it is just a small panel. So, in the effort to not waste material, how do I calculate how much epoxy I need, and what is the best way to mix small quantities? Some panels , or sections, maybe <3sf. A lot of times I just guess at the total quantity and mix accordingly, but either I end up with waste, or run short. is there any issue mixing 4 ounces of sprayable/brushable epoxy?

Thanks!
Rusty
 
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Hi Rusty:
I think the best approach is to make start with an educated guess and log the square footage and paint consumed. If your gun settings and techniques are consistent, you should be able to zero in the correct amount in a few sessions.
Ken
 
As a front yard hack myself, this is something I still struggle with too, though I've gotten a little better with time. My approach has been to take notes on how much volume went how far, and second, I always have several extra things prepared. If I have too much excess mixed up, I go ahead and spray the extra parts as well.
 
I use 1oz. disposable medicine cups for very small amounts. Also there are 8oz. disposable paint cups, using the smaller cup size helps accuracy. Like the others have said, keeping a log on what parts were sprayed and how much material was used becomes very valuable over time. I don't do this for epoxy but I do it for Speed Clear. Once you get some experience, you'll be able to make a batch for the first coat without having double what's necessary, then simply make a little more while waiting for the next coat so that you have the right amount for your second coat. I like to make sure that I have the amount used on the first coat plus about 10%, that way the gun won't suck dry and it will make up for any heavy handedness on the 2nd go around.
 
1oz maybe too small, but 8oz cups would probably be ok. :)

I'll start keeping a log of how much I mix up. I am already keeping a log of when , and how many coats, each panel is getting..

Rusty
 
These are the best 8oz cups I've used. With a 1:1 ratio like SPI epoxy you can mix just over 1oz if you are careful.
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Solo Cups allow you to mix 2 ounces at a time. The lines are very accurate. I actually use them often.
 
I don't like having to wash stuff, especially since I do not use cheap lacquer thinner as a cleanup solvent (it doesn't recycle well). But it's not a bad idea.
 
Chris_Hamilton said:
These are the best 8oz cups I've used. With a 1:1 ratio like SPI epoxy you can mix just over 1oz if you are careful.
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I have three of those E-Z 7 ounce cups. All three are about 1/2 ounce short from a true reading.

Here is 6 ounces in a Pyrex cup.
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Poured the 6 ounces from Pyrex cup into a one quart paint cup.
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Poured 6 ounces into E-Z 7 ounce cup.
As you can see, it's almost 1/2 ounce short of a true reading. I don't trust those cups.
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EZ Mix has a good reputation and I've never had any problems with them. If you found something that works for you better that's great. :) Mixed hundreds of gallons of various products through EZ Mix cups and never had any issues.
 
Chris_Hamilton said:
EZ Mix has a good reputation and I've never had any problems with them. If you found something that works for you better that's great. :) Mixed hundreds of gallons of various products through EZ Mix cups and never had any issues.
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I'm glad to hear you check measuring cups after you've purchased them for accuracy, and not trust them because you've had good luck with that particulate brand.

That's good advice for beginner painters.
 
Your post got me curious, so I did the same test that you did. 6 ounces in the EZ Mix cup and a 1 pint Dupont/Axalta cup. It was off though not as much as what yours was. Approximately 5.75-5.8 ounces indicated. The 1 pint Dupont cup indicated 6 ounces exactly.
So yes the actual measurements is off. But is it proportionatly off? That is more important because you mix within the cup. I took 2 of the ez mix cups and filled them with 3 ounces (indicated) each. Then poured one into the other. It correctly showed 6 ounces (indicated). So that shows that at least for that amount it is accurate. As long as it's proportionatly accurate that is all that matters.
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MJM said:
I'm glad to hear you check measuring cups after you've purchased them for accuracy, and not trust them because you've had good luck with that particulate brand.

That's good advice for beginner painters.
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No I don't check them for accuracy. This was the first time. Honestly I can't recall inaccurate cups ever being an issue. Either personally or with other guys. Biggest issue was guys not understanding proportions and ratios.
 
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The problem with using measuring cups IMHO, is that you have to combine the 2 parts and you are leaving some of both on the measuring cups when you transfer them. So not as accurate as it may seem.
 
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MJM, I can't really tell in your picture but it looks like the meniscus is too low to be accurate. That may be enough to throw it off.
 
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Then check the 'other' ratio mark amount if your depending on It to be correct if using one cup alone.
That is what seems to be killing everybody.
I use Pyrex glass beakers for mixing but I paint small now and 1 oz rts is 'normal including Clear.
 
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