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-   -   Primer Prep Problems (https://vansairforce.net/community/showthread.php?t=170906)

mulde35d 04-24-2019 07:46 AM

Primer Prep Problems
 
So I am getting what appears to be areas where grease was not properly removed from the aluminum and was hoping someone can't spot my problem area.

Each primer prep session goes something like this
1. Scuff parts using a maroon scotchbrite pad in a tub filled with warm water and Dawn dish soap.
2. Rinse parts and wipe them with a wet rag in a second tub filled with clean water.
3. While wearing nitrile non-powder coated gloves move parts from tub #2 to a third tub of clean water for a final rinse
4. Set parts aside to dry
5. Move parts into the paint booth (also while wearing nitrile gloves) and wipe with denatured alcohol and a clean lint free rag
6. Spray prime with SW Wash Primer or Alodine 1132 pen
7. Dry in the paint booth

For each skin sized piece of aluminum and especially on the interior corners of the ribs, the primer is beading like the aluminum hasn't been cleaned / degreased. All the parts are thoroughly scuffed which tells me I am getting those corners with the dish soap and I can't see any water breaks during the 3rd and final rinse, but I worry that it just isn't cutting the grease. The spots aren't real bad as it seems more cosmetic (the parts are holding the primer but it doesn't appear real uniform). I do however want to figure out the issue before I get to paint since the interior primer cosmetic issues don't matter, but the exterior paint will.

Does anyone see something glaring that I am doing wrong here, or have a better recommendation for a grease cutting agent than Dawn dish soap?

John-G 04-24-2019 08:28 AM

I only washed just few parts with Dawn. I decided to take another tact which worked for the Akzo primer I used.

While handling parts I tried, for the most part, to make it a point to wear gloves during drilling, deburring, ect. to minimize hand oils from adding contamination to the parts.

Prior to scuffing with ScotchBrite pads, I made it a point to clean the parts really well with Acetone using inexpensive general purpose white terry cloth towels. Then after scuffing the parts with maroon Scotch-Brite pads the parts were cleaned again repeatedly with Acetone and a towel until the towel was mostly clean. You want to use white towels so you can see how much gray from the aluminum is getting onto the towels. When it is just a tiny bit move onto the next part.

Spray the primer same day the parts are cleaned preferably within an hour or so.

I've also used the same method to spray SEM primer and have not had any issues.

wirejock 04-24-2019 08:31 AM

P60G2
 
A photo would help diagnose. P60G2 can spray blobs if mixed too thick. Your cleaning should be adequate if the surface is water break free. If so, there's no need for an additional wipe. Try Bon Ami cleanser instead of Dawn.

tims88 04-24-2019 08:42 AM

After seeing Larry (and others) recommend Bon Ami in the past, I decided to give it a try and I like it better than anything else I've tried so far. It seems to take less scrubbing than anything else I've used to get the aluminum to a point where water doesn't bead up on it.

Although, I've done several small parts with Dawn in the past and haven't had any trouble with it so I think it's unlikely to be the problem.

mulde35d 04-24-2019 09:07 AM

cleaning
 
I don't believe it to be the wash primer since I am having the same issue while using the Alodine 1132 pen. Also, I am using Sherwin Williams CM0484684 Chromated Wash Primer (similar but different if it matters). I had one issue early on that was similar which was that I used Acetone instead of Denatured Alcohol for the final wipe down. The Acetone leaves a residue which caused a lot of variation in the primer application. At the blog link below on 4-5-19 you can see what acetone did to the empennage primer spray (don't mind the extra primer on the rivets, that's just me spot priming after setting the rivets). While the variation due to the acetone was significantly more than what I am getting now, it is a similar type issue.

I will switch from Dawn to Bon Ami and see if that fixes the issue. Otherwise it sounds like it just may be not scrubbing long enough (which stinks because my fingers already get chewed up pretty bad from the scotchbrite pad during these cleaning sessions).

JonJay 04-24-2019 09:18 AM

Kleenstrip Prep-All is a relatively cheap wax remover and degreaser.
It’s much cheaper than DX-330 or other commercial paint prep cleaners and does just as good of a job. You won’t have issues with your parts being clean.

I recommend for any supplies like Scotchbrite substitutes, paint prep products, tapes, label removers, etc... go to your local auto body supply store. These folks sell to the professionals and they won’t use stuff that doesn’t work. They can’t afford it.
I have used dawn dish soap and water.
It’s fine, but a good degreaser wipes clean and evaporates. No secondary rinses required. I have had no comparability issues.
Good luck.

JonJay 04-24-2019 09:23 AM

Kleenstrip Prep-All is a relatively cheap wax remover and degreaser.
It?s much cheaper than DX-330 or other commercial paint prep cleaners and does just as good of a job. You won?t have issues with your parts being clean.

I recommend for any supplies like Scotchbrite substitutes, paint prep products, tapes, label removers, etc... go to your local auto body supply store. These folks sell to the professionals and they won?t use stuff that doesn?t work. They can?t afford it.
I have used dawn dish soap and water.
It?s fine, but a good degreaser wipes clean and evaporates. No secondary rinses required.
Good luck.

fl-mike 04-24-2019 09:37 AM

No pictures, so just throwing out some basic advice:
Use paper towels, not rags.
Silicone is prevalent in laundry softeners, and many other products like auto waxes. Banish anything the even "might" have been around silicone from your paint and prep areas.
Similarly, don't use syringes for measuring paint.

tims88 04-24-2019 10:09 AM

I did a quick google search about whether denatured alcohol leaves a residue and it looks like it can depending on what was mixed with the alcohol to denature it. The pictures on your blog make it look like the spots in the primer are following a long streaking pattern so it seems possible that it could be a result of wiping the parts down before you spray them.

mulde35d 04-24-2019 10:27 AM

The blog picture was definitely residue from using acetone. I have since changed to denatured alcohol, but didn?t realize that could streak as well. I?ll have to do some tests to see when the problem appears, but plan to start by switching from Dawn to Bon ami for degreasing.


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