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Re: Re-visit of cleaning metal prior to painting
They are probably not getting the parts very clean with the wipe
process. Are they just taking off light preservation oil? An aqueous
batch process with good rinsing should do a better job, in addition to
being cost-effective and low emmission. If they are phosphating
in-house, there are acidic aqueous based combination
cleaning/phosphoting products available. Two vendors I know of off hand
that supply them are DuBois and Oakite, there may be others as well.
There is an interesting case study published on closed-looping of such a
Recovery of an Aqueous Iron Phosphating/Degreasing Bath by
Ultrafiltration, Lindsey T.C., et al. J. Air & Waste Manage. Assoc. Vol
44, May 1944, p 697-701
If they are dead set on the wipe process, why not try a light odorless
Kirsten Koepsel wrote:
> 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).
> Kirsten M. Koepsel
> Texas Manufacturing Assistance Center
> 7300 Jack Newell Blvd., South
> Fort Worth, TX 76118
> 817-272-5977 (fax)
> firstname.lastname@example.org (e-mail)
> Juna Z. Snow
> List Manager
> IL. Waste Management
> & Research Center