Where the
world gathers for metal finishing
Q&As since 1989


-----

Sign maker asks about 3-layer Powder Coating. How?

I have been asked to powder coat treated aluminum to 3 layers. How do I do this ?

John Hoover
Sign Mfg. - Little Rock, Arkansas
July 22, 2008

---

First of two simultaneous responses -- July 23, 2008

If you only partly cure the first coat, then partly cure 2nd coat then apply top coat and fully cure it might work....

But you'd be best to ask the question WHY ?

Oftentimes a customer will ask a coater to do what the customer thinks is best, because someone told them a good trick, or a special process or something. Often they really don't know what they want, but want to sound knowledgeable.
For example, some think that the thicker the coating the better it is...

Ask what they're trying to achieve? What result do they want? Might be a much better way.

Sometimes they ask for something by a name they think its called, but really want something else.

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

---

Second of two simultaneous responses --

What do you mean by treated aluminium?
I think your client may only understand liquid paint requirements. One coat of wash primer, primer or finish and finally a top-coat clear. We supply several sign mf and the recognised process for aluminium destined for an outside locations, would be - chromating, polyester powder and if you wish to go over the top, a final coat of polyester or acrylic transparent (clear) powder. That would be the three coats. However, we do supply the alloy wheel industry with a three coat system - epoxy primer, epoxy/polyester aluminium base coat which is then over-coated with polyester transparent (clear) powder - giving you your three coat system. Nevertheless, do you require the aesthetic quality they look for in (OME) alloy wheels?

Terry Hickling
Birmingham, United Kingdom
July 24, 2008