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  #1  
Old 10-09-2021, 01:11 AM
skelrad skelrad is offline
 
Join Date: Mar 2005
Location: Redmond, WA
Posts: 226
Default Stewart Systems EkoPrime Test

If anyone's curious, I wanted to see how EkoPrime would stand up to abuse on an acid etch only surface vs an acid etch plus Scotch Brite scuffed surface. I primed parts a week ago and primed a scrap piece with half prepped each way. 24 hours after the primer was put on (cool weather, so I'm positive the primer still had a ways to go to truly cure), I hit it with a sharp awl. The awl cut through the acid etch only side with minimal effort. While it cut through the scuffed surface to an extent, it was not nearly as noticeable. In the picture, the acid etch only portion is the top half (right under the word "awl") and the scuffed portion is the lower half of the metal.

I tested again at 6 days, figuring that the primer should have largely cured to it's long term hardness. The primer stood up much better to the awl on the acid etch surface. On the scuffed surface, the awl really just burnished the surface. It took a fair amount of aggressive scratching to get through to aluminum at all.

So all in all, given the ease of spraying the EkoPrime (water borne - no 2 parts to mix or wait for), I'm very pleased with it. Yes, I've beat up a few areas on the parts that are having to deal with my riveting education, but for the most part all primed surfaces have held of wonderfully to the abuse of a newbie builder. For all of the empennage I scuffed every single part while using the EkoEtch. I'll likely continue to do that just because I like the added toughness, but I'd have a hard time arguing with someone who just decided to clean parts and spray with an acid etch and not scuff at all. The primer seems to stick pretty well regardless. Obviously that's only for internal surfaces that won't see long-term abuse.
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  #2  
Old 10-09-2021, 08:56 AM
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tyconnell tyconnell is offline
 
Join Date: Jul 2007
Location: Keller, TX
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Default

This is good info, as the EcoEtch, red Scotchbrite prep then EcoPrime is essentially the method I'm now using.
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  #3  
Old 10-14-2021, 04:34 PM
DCorwith DCorwith is offline
 
Join Date: Jul 2007
Location: Water Mill, NY
Posts: 42
Default Thanks for posting good info

Thanks for posting. Good info to know. Great product.
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  #4  
Old 10-23-2021, 10:50 AM
nerdwithoutacause nerdwithoutacause is offline
 
Join Date: Sep 2021
Location: Hamburg, Germany
Posts: 2
Default

Really interesting information and thanks for sharing.

I am waiting for the empennage and thought I would play around with some processes. I am working on painting/Priming and have got a sample kit from Stewart Systems. So far I like - but I haven't sprayed EkoPrime yet. Today I was playing with EkoClean and EkoEtch on a scrap piece of Aluminium.

I actually came on here to get an opinion of my testing. What I did was prepare two zones on the scrap piece, one I treated as per Stewart System's instructions (Clean then Etch) and then other I cleaned with MEK after EkoClean.

In both tests I cleaned until the EkoClean cloth was "rubbing clean". But I was shocked how dark the MEK cloth was afterwards. So it did lift further dirt off the surface.

So I am actually wondering, whether to clean with MEK and then EkoEtch, skipping the EkoClean step.

Given I am in Europe and the time now, I will stop, and I'll re-run my tests tomorrow, and spray with EkoPrime.
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  #5  
Old 10-23-2021, 11:11 AM
wirejock's Avatar
wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 4,775
Default Bon Ami

Try something less toxic as a third.
Maroon scotchbrite, Bon Ami. Scrub to water break free surface. Dry. Paint within 2 hours.
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Estes Park, CO
wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #6  
Old 10-23-2021, 12:12 PM
skelrad skelrad is offline
 
Join Date: Mar 2005
Location: Redmond, WA
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Default

Quote:
Originally Posted by nerdwithoutacause View Post
Really interesting information and thanks for sharing.

I am waiting for the empennage and thought I would play around with some processes. I am working on painting/Priming and have got a sample kit from Stewart Systems. So far I like - but I haven't sprayed EkoPrime yet. Today I was playing with EkoClean and EkoEtch on a scrap piece of Aluminium.

I actually came on here to get an opinion of my testing. What I did was prepare two zones on the scrap piece, one I treated as per Stewart System's instructions (Clean then Etch) and then other I cleaned with MEK after EkoClean.

In both tests I cleaned until the EkoClean cloth was "rubbing clean". But I was shocked how dark the MEK cloth was afterwards. So it did lift further dirt off the surface.

So I am actually wondering, whether to clean with MEK and then EkoEtch, skipping the EkoClean step.

Given I am in Europe and the time now, I will stop, and I'll re-run my tests tomorrow, and spray with EkoPrime.
Not knowing anything about this process when I started, I bought both the EkoClean as well as the EkoEtch. After talking with Stewart, I learned that EkoEtch actually has detergents in it, so if you are going to use it along with schotch brite to etch, it'll clean the metal just fine. I use the etch and scotch brite, and after the recommended 3ish minutes of time for a part, I simply rinse it off with a garden hose. I usually use a rag to dry parts off just to speed things up, and very occasionally I'll get a SLIGHT amount of grey on the rag as I dry. After one swipe with the drying rag, no more grey though. In my first batch, I was the typical worried new guy, so pulled out some acetone to wipe the parts down more, but it really didn't pull anything else off the parts. Personally, from my limited experience, I would say you'd be overdoing it to clean with anything on top of using EkoEtch as long as you rinse thoroughly.

Just from my very limited experience, I am going to change how I do things in future prep. I was originally super worried about a great etch, so I spent a ridiculous amount of time scuffing with the scotch brite while using EkoEtch. Overkill in a big way and man, it's exhausting! For interior surfaces that aren't going to get abused, from what I've seen, the primer is going to stick just fine with minimal prep work.

When talking with Stewart, they actually said that in reality as long as you have clean metal after using EkoClean, the primer is going to stick well enough to do its job, even without any etching at all. This is for internal surfaces that will never be touched of course. That's one test I haven't done, but for internals, I think they're probably right. It's easy to get caught up in trying to find the absolute best solution to something and forget that the line between "good for the intended job" and "absolute best" is sometimes not even perceptible, but the "best" approach is 2x the effort. You have to decide where the line is for you. For me, I will lightly scuff as I clean parts with EkoEtch, but mostly I'll let the etch do its job. I'm really only lightly scuffing as I clean the parts, not the aggressive scuffing I was doing before for fear of primer peeling off when I looked at it wrong. For internal parts that will never see the light of day, the value in a perfectly, manually etched part is not big enough to justify the added effort and time in my opinion.

Maybe during my next priming day I'll test a piece that has been cleaned only, but with no etch. That's probably not a direction I want to go, but would be interesting to see the outcome and if the primer flakes off with bending or any kind of abuse.
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  #7  
Old 10-24-2021, 10:58 AM
nerdwithoutacause nerdwithoutacause is offline
 
Join Date: Sep 2021
Location: Hamburg, Germany
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Default

Quote:
Not knowing anything about this process when I started,
Exactly where I am. My first ever "squirt" with a spray gun was today for my trials. I have watched many youtube videos on gun setup etc. I'd say it went "OK" - I need to allow a bit longer between coats and I did spray too much on, so I got a few "High Corners" where the paint ran to. And I probably need to improve the lighting in the garage

Quote:
Try something less toxic as a third.
I will do, living in Germany, everything was closed today, so I'll grab some Iso and Acetone from the DIY store tomorrow, and run a few more tests/practice sprays, before I attempt to paint the Vans Practice Flap Kit.

But just to share with the thread the results of today, in the attached photo from left to right I did the following. Far Left, exactly per Stewart Systems instructions (EkoClean/EkoEtch with Scotch Brite/Rinse/EkoPrime), centre left sample added a MEK clean (EkoClean/EkoEtch with Scotch Brite/Rinse/MEK Wipe/EkoPrime), centre right sample was Silicon Cleaner/mechanically etched with MEK and Scotch Brite, and the far right was cleaned with Silicone Cleaner, then cleaned with MEK and then etched with EkoEtch and Scotch Brite, rinsed with water.

I think the far right sample is probably marginally the best, (and it is marginal) but the left and centre left are about equal and just a tiny bit behind. The centre right, which was not chemically etched is the worst.

Quote:
Maybe during my next priming day I'll test a piece that has been cleaned only, but with no etch.
I'll be interested in your results, for me it was the worst sample without the chemical etch, whether it's good enough though, I think is more a subjective thing, because I agree with you on the below quote.

Quote:
It's easy to get caught up in trying to find the absolute best solution to something and forget that the line between "good for the intended job" and "absolute best" is sometimes not even perceptible, but the "best" approach is 2x the effort. You have to decide where the line is for you.
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  #8  
Old 10-24-2021, 04:26 PM
wirejock's Avatar
wirejock wirejock is offline
 
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Location: Estes Park, CO
Posts: 4,775
Default Aluminum Oxide

The samples don't appear to be etching issues. To me they look contaminated. The fisheyes look like silicone or oil contamination. Keep silicone products in another city!

The enemy of adhesion on aluminum is aluminum oxide. Similar to the thin layer of rust that quickly forms on steel. It forms very quickly. Paint doesnt stick well to it. It's only a few microns thick and easily removed chemically or mechanically. Etching products are usually acid. They react and remove it while etching the surface so the paint can bite. Mechanically etching with scotchbrite and a cleanser works very well. Ajax and Comet work well but contain sodium hypoclorite (bleach). They can be used provided the surface is rinsed very well.
Solvents only clean the surface. They can't chemically remove the aluminum oxide layer. They have a place but there are safer choices for cleaning off contaminates. Coleman fuel or even Isopropyl alcohol work very well and far less dangerous to humans. Find a method you like to remove the aluminum oxide then paint within two hours before it reforms. Acid etch or scrub, wipe just before paint with a cleaner then shoot.

Test samples after cure by rubbing a piece of black Gorilla tape on the surface then rip it off. If the paint sticks, congratulations. That process is ok. If it rips the paint off, try something else.

Bottom line, harsh chemicals like MEK are not needed. Try to stay away from that stuff. Faster a solvent evaporates, the faster your body absorbs it. Save it for fuel tanks.
YMMV

I'll step off my soapbox now.
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Estes Park, CO
wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #9  
Old 10-24-2021, 04:40 PM
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bjdecker bjdecker is offline
 
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Location: Georgetown, TX
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Default

Quote:
Originally Posted by nerdwithoutacause View Post
So I am actually wondering, whether to clean with MEK and then EkoEtch, skipping the EkoClean step.
This is intended as humor, PSA and best practice; ...What Larry (wirejock) said...

Leave the MEK in the can, on the back shelf, away from people -- your liver & brain will thank you and you'll have more processing capability for beer...

I think you'd be better served scuffing, then cleaning with Dawn (dishwashing detergent) and water rinse -- OR -- denatured alcohol then apply the etch+primer.
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  #10  
Old 10-24-2021, 04:51 PM
wirejock's Avatar
wirejock wirejock is offline
 
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Location: Estes Park, CO
Posts: 4,775
Default Beer

Quote:
Originally Posted by bjdecker View Post
<snip>
you'll have more processing capability for beer...
<snip>
Now them is some wise words!
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Larry Larson
Estes Park, CO
wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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