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  #11  
Old 04-24-2019, 10:28 AM
Mudfly Mudfly is offline
 
Join Date: Dec 2011
Location: Alpharetta, Ga
Posts: 212
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Your step 4. "set parts aside to dry"

I noticed that when I use to let parts air dry, I sometimes ended up with small areas that were slightly "discolored" looking. I assumed the areas were water spots left over from the air dry process. I don't recall any adhesion issues, but something was different when priming those areas. I now use a blow dryer to dry all parts after final rinse. I no longer use rags or paper towels because of the possibility for contamination. Also, I discovered when using paper towels that occasionally very small pieces of the paper towel were left sticking to the aluminum.
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  #12  
Old 04-24-2019, 11:05 AM
jacoby jacoby is offline
 
Join Date: Jul 2018
Location: WNC
Posts: 246
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I'm using the Akzo primer but I've also had great results with the bon ami. I also use Southern Polyurethanes waterborne wax and grease remover after rinsing and drying the part. I use wypall x80 cloths since they are durable and (mostly) non-linting.

The bon ami is fast too. I scuffed each of the HS skins on my 10 in under 10 minutes. I only needed to touch up a couple of small places.

I don't use any solvents beforehand; that just takes more time. The bon ami instantly takes off any residual red lettering and sharpie. Most solvents just smear wax and grease around and then evaporate. Using a product designed to clean the surface works significantly better.
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  #13  
Old 04-24-2019, 11:28 AM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,947
Default Surface prep

Pardon while I step on my soap box.
The culprit is aluminum oxide (Al2O3). It's only a few mils thick but it's the enemy of adhesion. Solvents won't remove it. Paint doesn't stick very well to it. Paint also sticks best to an abraded surface. Maroon Scotchbrite does a nice job of scuffing and with the addition of Bon Ami or even Comet or Ajax, the Al203 layer is removed along with any traces of contaminants. Comet and Ajax have bleach so you want to rinse them really well. The Al203 begins reforming immediately in the presence of O2 so you want to shoot primer as soon as possible.
If you want to save the hands, a scotch brite pad works well on a random orbital sander. It's fast. Only a light pass is needed to scuff. However, the wash step is still required. I use gray scotch brite and Bon Ami.
Test your prep method by applying black Gorilla tape to the cured surface. Rip it off.
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Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
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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  #14  
Old 04-24-2019, 11:34 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
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All water based washing should be before you final scuff, otherwise you are pushing the grease deeper into the crevices and all the water exposure is accelerating the corrosion. Post scuff, use a wax and grease remover before applying paint. This also helps to remove the debris caused by scuffing. Paint should go on within 2 hours of abrasion.

I often use a scuff pad while cleaning with detergent. However, I also do a final scuff and clean with W&G remover right before paint application. You need compressed air and a good amount of drying time after the detergent treatment. Water finds its way into crevices and you don't want to paint over that. No real issue with small parts, but a big problem for assemblies.

Larry
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Last edited by lr172 : 04-24-2019 at 11:43 AM.
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  #15  
Old 04-24-2019, 12:04 PM
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mulde35d mulde35d is offline
 
Join Date: Dec 2017
Location: Lithia, FL
Posts: 217
Default next steps

So here is what I am thinking I'll try next.

1. Wipe / clean with Prep-All cleaner / degreaser
2. Scuff with maroon scotchbrite pad in Bon Ami / water solution
3. rinse and wipe in clean water
4. blow dry and move into paint booth
5. Spray prime or apply Alodine 1132

We'll see how it works. The good part about the Alodine pen is that you can clearly see if you have any remaining grease marks while applying. Much easier to correct if you do have marks than when spray priming.
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Last edited by mulde35d : 04-24-2019 at 03:09 PM.
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  #16  
Old 04-24-2019, 01:14 PM
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az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
Question

I noticed that the Akzo primer actually absorbed water when I painted to late in the day.

I was living 1-2 miles from the ocean at the time though.

Could you be having similar problems?
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  #17  
Old 04-24-2019, 04:04 PM
jacoby jacoby is offline
 
Join Date: Jul 2018
Location: WNC
Posts: 246
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Quote:
Originally Posted by az_gila View Post
I noticed that the Akzo primer actually absorbed water when I painted to late in the day.

I was living 1-2 miles from the ocean at the time though.

Could you be having similar problems?
What did that look like? The only time I've seen water in primer is when my separator filled and it started spitting water drops. I've never seen paint or primer pull it out of the air
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  #18  
Old 04-24-2019, 04:57 PM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
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Quote:
Originally Posted by jacoby View Post
What did that look like? The only time I've seen water in primer is when my separator filled and it started spitting water drops. I've never seen paint or primer pull it out of the air
Essentially that is what it did in the high humidity before it cured.

It may have been not dry enough and it didn't stick...
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Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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  #19  
Old 04-24-2019, 05:01 PM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
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Default Prep

Quote:
Originally Posted by mulde35d View Post
So here is what I am thinking I'll try next.

1. Wipe / clean with Prep-All cleaner / degreaser
2. Scuff with maroon scotchbrite pad in Bon Ami / water solution
3. rinse and wipe in clean water
4. blow dry and move into paint booth
5. Spray prime or apply Alodine 1132

We'll see how it works. The good part about the Alodine pen is that you can clearly see if you have any remaining grease marks while applying. Much easier to correct if you do have marks than when spray priming.
I recommend using a hair dryer to blow dry just in case. Compressor air can have contaminants. I actually use clean shop paper towels to dry. It also removes residue from the water. Especially important if your water has a lot of minerals. Save the paper towels for other uses in the shop. You got this.
Also, just in case, I mix P60G2 1 part primer to 2 parts catalyst. Very thin. Spray till only a hint of color can be seen. Usually two passes at 90°.
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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
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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  #20  
Old 04-24-2019, 05:17 PM
JonJay's Avatar
JonJay JonJay is offline
 
Join Date: Jan 2007
Location: Battleground
Posts: 4,348
Default

Quote:
Originally Posted by mulde35d View Post
So here is what I am thinking I'll try next.

1. Wipe / clean with Prep-All cleaner / degreaser
2. Scuff with maroon scotchbrite pad in Bon Ami / water solution
3. rinse and wipe in clean water
4. blow dry and move into paint booth
5. Spray prime or apply Alodine 1132

We'll see how it works. The good part about the Alodine pen is that you can clearly see if you have any remaining grease marks while applying. Much easier to correct if you do have marks than when spray priming.
All-Prep is used as a ?final wipe?. You don?t want to introduce water after. Water is the last thing I want on the surface of my part even with a thorough drying. Unless youre using distilled water, you will leave trace minerals and maybe even chemicals behind. Many get away with it, but it simply isn?t necessary to go through the process.
You will go through a lot of clean rags but Scotchbrite and then Prep-All is all that is needed. I am sorry, but Scotchbrite isn?t going to embed contaminates in the scratches. If your aluminum is so greasy and dirty that there is a concern, you could clean it, dry it, and then Scotchbrite, but I never do. Fingerprints, human oils, silicon, etc.... the Prep-All will take care of it after you Scotchbrite. Follow the directions on the Prep-All label. Simple.
You are not in a production environment so if you want to add steps you can, but the pros don?t. That?s why these products where developed. Prep and priming take a long time in the build process. Why not make it simple and easier with the right products? Your not washing dirty greasy dishes.

By the way, Dawn isn?t the same it used to be. They still make Classic Dawn, but it still is different and may have added scents and other chemicals. Also, it is much more concentrated than before. Not the same which could be why folks may have trouble using it like they did back in the day. Just a guess.
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