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Cleaning painted parts before painting?

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Hi gang, I'm not a RV builder but VAF has a bit more experience than our support forum, hope you don't mind me tapping your brain trust.

My kit (SeaRey) comes with some metal parts already painted white, my build got delayed for a few years (life, usual stuff), we're finally getting her ready for paint and the parts have a fine layer of hangar dirt on them. Any suggestions for cleaning without leaving residue behind or causing them to rust? I was thinking Windex or 409, tried just wiping them down but it's not enough, and I don't want to go the full "bathtub full of Dawn and rub-a-dub-dub" route unless I have to.



Thanks
 
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Mechanical adhesion

I think the bigger issue is abrading the surface with 400 so the next coat of paint has some tooth to stick. Of course after scuffing, you'll have to wash.
Dawn is a good choice followed by a thorough dry then a quick wipe with a solvent and finally a tack cloth right before spraying.
If you already plan the prep and just want to clean the hangar dust, I would go Dawn. Other cleansers may leave unwanted resedue.
 
For cleaning parts prior to painting Southern Polyurethane's (SPI) 700 Waterborne Wax and Grease Remover is my product of choice. SPI's website is here https://www.southernpolyurethanes.com/ and the product info here https://docs.wixstatic.com/ugd/8ced3e_4b60abf438f4488bbff7b43ca106bb47.pdf

A fine alternate is dawn dish soap and then after it is dry cleaning with Naphtha (it is also sold a camping white gas). I feel it is important to add a solvent cleaning step in addition to the water based dish soap to insure a clean part.
 
It sounds like rust isn't a problem, so that is good!

You can try Aviation Simple Green. Not the stuff you get at your local auto parts store but the expensive stuff from Aircraft Spruce.
 
You probably know this as well but be sure to not use just any old shop towel to wipe down your cleaned parts (before tack cloth and paint). If the "shop towels" were washed and dried with other greasy rags or fabric softener used, or in a dryer with a lot of fabric softener build up in the drum, the shop towel may have a little bit of residual product that may give your paint some attitude when coating or drying (fish eye, etc). I've used shop paper rags before too, be sure the product is clean and dry with no additives put in for other purposes and your gloves are on so oils from your hands don't come in contact with the prep surface as you work.
 
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Didn't know that, Eddie, but Thanks. I used an old t-shirt I had never worn or washed.

I'll be sure to talk to the gent doing my painting before we start, knowing him he'll probably have me wash them all over again under his watchful eye. Which is fine. :)
 
I've been using denatured alcohol and new from the bag yellow microfiber cloth (the big bundle from Costco) as the final wipe just before paint or primer.

On bare aluminum, I'll clean with acetone to get all the ink and skin oils from handling. Then, follow up with the alcohol. Once I begin the final wipe with alcohol, its clean nitrile gloves only.

Primed surfaces get a sponge wash with distilled water. After complete drying and when surface is up to temperature, final wipe with alcohol and new cloth.

Is this not the right way to do it?
 
I've been using denatured alcohol and new from the bag yellow microfiber cloth (the big bundle from Costco) as the final wipe just before paint or primer.

On bare aluminum, I'll clean with acetone to get all the ink and skin oils from handling. Then, follow up with the alcohol. Once I begin the final wipe with alcohol, its clean nitrile gloves only.

Primed surfaces get a sponge wash with distilled water. After complete drying and when surface is up to temperature, final wipe with alcohol and new cloth.

Is this not the right way to do it?

+1 for alcohol. Not as harmful as acetone for your health, get it at the drug store and it is a good degreaser. I also use it for degreasing prior to welding anything - steel or aluminum. Also, if you have anything with silicone on it, get it the heck away from anything you want to paint. A guy here with a paint shop won't even allow tubes of silicone to be in the shop! If you have applied some caulking and cleaned off the excess with a rag, get rid of the rag. Oh, also +1 on scuffing with 400 grit.
 
The old adage applies here, "data doesn't lie". As a professional quality engineer let me just point you to some real testing that speaks for itself.
I found this on this forum when I searched ("method to prep for paint"). What came up was a post titled "Dan Gelbart Fabrication Tips"
When in doubt always test and verify any opinions. This video shows you how. It is spot on correct. (Side note, I will condone the use of Acetone...it does work as a fair degreaser, BUT ONLY prior to using the product in Dan Gelbart's video.) And an unequivocal NO on alcohol. Take a look. Again, is 100% absolutely correct. Try this link, https://www.youtube.com/watch?v=x7onZGqrYyY
If that doesn't work, just search forums here for Dan Gelbart.

Key is always validate any opinions you get on here. Point for this post is do the so called "water test" for your own evidence.
 
Link

The old adage applies here, "data doesn't lie". As a professional quality engineer let me just point you to some real testing that speaks for itself.
I found this on this forum when I searched ("method to prep for paint"). What came up was a post titled "Dan Gelbart Fabrication Tips"
When in doubt always test and verify any opinions. This video shows you how. It is spot on correct. (Side note, I will condone the use of Acetone...it does work as a fair degreaser, BUT ONLY prior to using the product in Dan Gelbart's video.) And an unequivocal NO on alcohol. Take a look. Again, is 100% absolutely correct. Try this link, https://www.youtube.com/watch?v=x7onZGqrYyY
If that doesn't work, just search forums here for Dan Gelbart.

Key is always validate any opinions you get on here. Point for this post is do the so called "water test" for your own evidence.

Thanks for posting that. I watched that before starting my build. I've posted about scrubbing with cleansers several times. Even posted on my blog trying to explain hydrophobic vs hydrophilic. BTW, all my test parts pass the Gorilla tape test. Looks like I can step off my soapbox now.
 
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