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RE: Re-visit of cleaning metal prior to painting



Hi Kirsten,

I see a number of problems right from the start.  The forming operation
could be fouling the phosphate treated surface with oil.  Since the treated
metal is porous, it is much more difficult to clean.  They should either
form the metal then clean and phosphate or switch from hand wiping to
immersion cleaning and drying.

As for the paint, a 1 to 2 day cure time is excessive.  Are they located
near the coast?  High humidity can drastically extend dry times.  I would
suggest they properly cure the boxes after painting.  Perhaps a small IR
oven would work.  They should also look into their painting operation to
make sure that the paint is mixed and applied consistently.  Do they have a
coating specification ?  Too thick or too thin a coating can also affect
performance.

Just some thoughts,

Mike.callahan@jacobs.com
> ----------
> From: 	Kirsten Koepsel[SMTP:kkoepsel@arrirs04.uta.edu]
> Reply To: 	Kirsten Koepsel
> Sent: 	Tuesday, August 17, 1999 8:16 AM
> To: 	p2tech@great-lakes.net
> Subject: 	Re-visit of cleaning metal prior to painting
> 
> Hey guys,
> 
> Several months ago, I solicited some advice for one of my 
> manufacturers. I now have additional info since they contracted to 
> have this problem solved.
> 
> Here are the details:
> 
> Process steps: form metal, clean, paint, air dry, assemble
> 
> 
> Metal is phosphate treated zinc galvanized cold rolled steel
> 
> Cleaning process by handwiping formed metal boxes: use this 
> method since a large majority of their painted product is already 
> assembled prior to painting
> 
> Cleaner contains-toluene, MEK, acetone, isopropanol, xylene. 
> They are interested in changing to a less VOC/HAP oriented 
> cleaner but the paint not sticking is the primary issue right now.
> 
> Paint-two kinds: one is an urethane/acrylic polymer (gray color) 
> and the other is acrylic polymer (bone color). The acrylic polymer 
> (bone color) is the one they are having problems with. They are 
> moving to all bone color boxes.
> 
> The drying time is approximately 1-2 days for the bone color 
> boxes before being assembled onto the rest of the parts. No 
> drying oven is used.
> 
> Observations: Flaking on edges, paint comes up as screws are 
> torqued, able to peel paint off in one piece instead of in flakes.
> 
> Any suggestions as to how to alleviate the paint peeling process? 
> 
> I do have the MSDS sheets from the paint manufacturer. They 
> have even been out to vist the manufacturer and haven't been 
> able to come up with a good answer.
> 
> They are looking to move into a major consumer market and paint 
> peeling is not a good thing (in the words of Martha Stewart).
> 
> Thanks.
> Kirsten
> 
> 
> 
> 
> 
> Kirsten M. Koepsel
> Texas Manufacturing Assistance Center
> 7300 Jack Newell Blvd., South
> Fort Worth, TX  76118
> 
> 817-272-5925
> 817-272-5977 (fax)
> kkoepsel@arri.uta.edu (e-mail)
> 
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