RudiGreyling
Well Known Member
Hi Guys,
I asked Highflight a question in a PM which I think we all might benefit from, so I am re-posting here with his permission.
I asked Highflight a question in a PM which I think we all might benefit from, so I am re-posting here with his permission.
His Answer:greylingr said:
Highflight said:HI Rudi,
The use of pre-cleaning materials is a pretty simple thing so don't let it be more than it is.
The short story is that you need a solvent to both dissolve AND float the contaminant from the surface of the finish.
Your friend is half right when he says "it was the wrong thing to do since it would thin the oil and not get rid of it", but he is showing only a partial understanding of the process by that comment.
The correct pre-cleaning solvent does "thin" (dissolve) the contaminants, but that's only a part of the process.
NO solvent of any kind will "get rid of it" by itself. That would require a suspension of a basic law of the universe where "matter cannot be created nor destroyed". (in this case, you just want the contaminant "matter" to go somewhere else)
Here's the detailed story of what's going on:
First, the solvent you use has to do two things. It has to "dissolve" (or as your friend said; "thin") the contaminant, and just as importantly, it has to put it AND KEEP IT in suspension WITHIN the solvent.
Second, the solvent MUST stay wet long enough for you to be able to wipe if off with a CLEAN DRY cloth because what you are doing is wiping off the wet solvent with the contaminant IN it. No cleaner "gets rid" of a contaminant; the contaminant is removed by putting it in suspension in the solvent and then removing (wiping off) the solvent.
If you just wipe the solvent around on the surface but then let it dry there, any contaminants suspended in that solvent will simply stay on the surface after the solvent eventually dries up.
Also, you should have several clean dry wiping cloths on hand so that you can grab a clean dry fresh one as the first one becomes wet.
To say it again, it is IMPORTANT to wipe off the wet solvent from the surface and NOT let it dry on the surface. It never hurts to "wipe with solvent, then wipe dry"... then repeat 2 or 3 times.
The explanation above of how pre-cleaning solvents work is why you shouldn't be using paint thinners or any other product OTHER THAN THAT FORMULATED FOR THE PURPOSE!
Cleaners that are formulated for the purpose of de-greasing/pre-cleaning a surface before painting are specifically made to be a very aggressive solvent for dissolving the majority of (typical) contaminants you come up against. And very importantly, cleaner-specific formulas are designed to not evaporate very fast giving you a lot of time to wipe it off while it is still wet.
Paint thinners usually evaporate too fast, and additionally, thinners and other chemicals may contain product specific ingredients of their own that could be left behind and create other problems in the paint finish.
If you're near a PPG auto paint store, pick up a gallon or two of DX330 "Acrili-Clean" which is PPG's product designed for the purpose of pre-cleaning a surface before painting.
If you like Dupont, I believe they call theirs "PrepSol".
You should be able to find the product bulletins for either of those two products on the Internet, but all you really need to know is that you use either one by wiping on generously (sloppy) wet, and then wiping off immediately and thoroughly with a clean, dry cloth.
The reference to a "tack free cloth" by your friend is also known in the trade as a "tack cloth" or "tack rag".
All that is, is a gauze cloth that is impregnated with a mildy sticky medium (non-contaminating) that you gently wipe over a surface AFTER it's been thoroughly cleaned with DX330 and dried. The only purpose of the tack cloth is to pick up any dust that will show up in the sprayed finish.
The moment you are finished wiping the surface with the tack cloth, you go immediatly into spraying your material.
Hope that helps.
Vern
