Test time is play time!

Barry

Barry

Paint Fanatic
Staff member
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One of the things I enjoy most is testing and it is on going and here is a good general spray test with epoxy.
First, the 55-gallon drums you see in the picture are our empty's right now there are 94 of them and when we get 150 to 175 we call the certified drum recycler.
Now for how I do all batch testing.
The black drums are solvent drums, blue drums are polyols and the reds are Iso's.
I NEVER clean the drums, I don't sand the drums all I do is dust if needed and spray.
The epoxy I sprayed two wet coats without flash time between coats and you will notice in one spot I tried to run it. Success!!!
This was yesterday at 80 degrees and 85% humidity.
Not one solvent pop but I had 157lbs at the wall gauge and 28Lbs at the gun, using Iwata LPH400 with a 1.4 tip.
Normally solvent pop is caused by too low air at wall or gun and dry spraying.
For the 2 coats, average mils are 1.8 to 2.2 not counting run area.
18 hours later I have 85% adhesion and that is right about where the epoxy should be BUT that is with no prep and also all the black drums come with .04 mils of paint.
just fun play time though you might be interested.
 
I have always struggled with the first coat of epoxy if I'm trying to lay it on wet and not using enough air. Sometimes I have to spray panels out on the shop floor and too much overspray out there is just generally bad. Sometimes a light coat per panel followed immediately by a full coat works good in those situations, but I wonder if there's something being given up in the way of adhesion. I like to think not, since the full coat is immediate, but who knows.
 
Like I say all the time, its what works for you and doing it med and right away with a wet, no adhesion issue.

About an hour ago I to a single edge razor to edge at tape mark and could not chip or move and this thing is not even prepped.
 
Would the
Barry said:
Like I say all the time, its what works for you and doing it med and right away with a wet, no adhesion issue.

About an hour ago I to a single edge razor to edge at tape mark and could not chip or move and this thing is not even prepped.
Click to expand...

Would the solvents in the epoxy 'bite' into the black drums paint and create stronger adhesion?

I'm thinking the same test in media blasted metal or 80grit DA would give you very similar results though.
 
we recommend 180 but we have people that use a grey or red scuff pad every day.
 
Jorge M. said:
Would the


Would the solvents in the epoxy 'bite' into the black drums paint and create stronger adhesion?

I'm thinking the same test in media blasted metal or 80grit DA would give you very similar results though.
Click to expand...

Formulating 101:
If your product relies on solvent for adhesion, your product is in big trouble.
Solvents in an epoxy may make a 1-3% help at best.
 
We use red scuff on OEM metal, but on exterior surfaces we make sure that ALL the gloss is gone, which takes about three times as long. Standox Non-Stop 2K sealer seems to work even on completely unsanded e-coat, but I haven't tested SPI epoxy this way.
 
Barry said:
Formulating 101:
If your product relies on solvent for adhesion, your product is in big trouble.
Solvents in an epoxy may make a 1-3% help at best.
Click to expand...

Thanks Barry, that makes a lot of sense.

There's a resto shop here in BC that buys a lot of the epoxy, every time I drop it off he has something sitting in epoxy. Most of the time I poke around the edges and never seen weak adhesion.
 
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