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topic 24567

Paint peel off problems


A discussion started in 2003 but continuing through 2018

(2003)

Q. Dear Sir,

At one of our clients location we are facing a severe paint peel off problem from hot and cold rolled sheet metals used for manufacturing of earth mover (OEM) machines. Existing method:
1) Components are cleaned manually with alkaline degreasing chemical
2) Pretreatment ( Bath system) followed by
3) Manual cleaning with emery paper, then final wash with thinner or IPA.

despite all this tedious exercise we are facing peel off problem (entire strip) In this regard we seek your help what are the possibilities? Your earliest response will be off great help for us.

Thanking you,

Sadashiv Gugawad
Cleaners - Pune, Maharashtra, India


simultaneous (2003)

A. Earth movers are a rather large item in the powder coating spectrum. Aside from cleaning, I would look closely at the cure of the powder coating. I'm not sure of the gauge of metal and the cure schedule or media used for your application, but I am assuming that the substrate is thick (real thick). Perform a pencil hardness and MEK / methyl ethyl ketone rub test to the current cured film to detect softness indicative of an under cured powder coated surface. If cure is suspect, try to extend time at temperature until these tests are acceptable, and hope that your cleaning is sufficient. If the powder is cured and still failing, you can focus on the metal prep as the problem. If the cure is the problem look at an IR "boost" to a conventional gas fired oven to maintain efficiency.

Andy Peal
- Grand Rapids, Michigan


(2003)

A. Check your pretreatment line; surely there is some problem. Check your first stage (degreasing) by water break test.

Derusting is a must. Process to follow: Degreasing-wr-wr-derusting-wr-wr-phosphating-wr-wr(DM)-passivation-dry-coating.

Rakesh Sharma
- Delhi, India


(2003)

A. Dear Mr. Sadashiv Gugawad,

In case you are talking of paint peel off in places which are not undergoing abrasive action during operation of the earth moving machinery then there seems to be a problem in your method of pretreatment.

A good pretreatment and the correct paint will protect the paint from peel off. Could we know what type of paint are you currently using?

Regards,

Sandeep Kundra
manufacturers of metal pretreatment chemicals - Bombay, Maharashtra, India


July 13, 2011

A. Dear Mr. Sadashiv Gugawad,

In case you are talking of paint peel off in places which are not undergoing abrasive action during operation of the earth moving machinery then there seems to be a problem in your method of pretreatment.

A good pretreatment and the correct paint will protect the paint from peel off. Maintain the Water Rinse pH value, Chemical bath Pointage, Baking Oven Temp., Conveyor Speed and D.F.T.

Regards,

Popat Bhise
Assist. Manager Powder Coating Dept, - Pune, Maharashtra, India


July 28, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi,

I ship MS products. I tried a few enamel paints but none of them worked. By the time the shipment reached, paint had completely come off from the surface.

I am new to the paint. And I couldn't find the exact query on other forum. Can anyone please suggest me what kind of paints are required? Or if a proper way of packing or different type of container can make things better for me?

Many thanks in advance.

Aseem Patel
- India


July 30, 2012

A. Hi Aseem.

Although packing is important, poor packaging is not what made the paint peel off. It peeled off because the pretreatment before painting was inadequate.

We have appended your inquiry to a previous thread which should give you a starting point. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



January 8, 2018

Q. Dear Sir,

At one of our clients' locations we are facing a paint peel off problem from hot and cold rolled sheet metals used for manufacturing of bikes Chain Case (Honda) machines. Existing method:
1) Components are cleaned manually with alkaline degreasing chemical
2) Pretreatment (Bath system) followed by
3) Manual cleaning with emery paper, then final wash with thinner or IPA.

Despite all this tedious exercise we are facing peel off problem (Tail side Surface) In this regard we seek your help what are the possibilities? Your earliest response will be of great help for us.

Thanking you,
Regards

asad_mumtaz
Asad Mumtaz
engineering works - Lahore Pakistan


January 2018

A. Hi Asad. I may be misunderstanding what you wrote, and you seem to have "cut & pasted" from previous postings, but the process sounds backwards to me :-)

If you need emery paper sanding it should be done before the (phosphatizing?) pretreatment, not after it.

Again, I might be misunderstanding you, but I think the correct process would be:
1. Emery paper sanding
2. Alkaline degreasing
3. Phosphatizing pretreatment
4. Painting (no thinner or IPA step).

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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