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


-----

What Powder Coating Thickness to Shoot For

What coating thickness is recommended for outdoor products? 14-16 gauge CR mild steel, iron phosphated, powdered with Polyester TGIC. Currently we aim for 2-3 mm^milsthickness. Thanks.

Rollin Heide
job shop employee - Manitoba, Canada
November 9, 2010

I think that there may be a misprint in your question i.e. applying 2 - 3 mm -- this equates to 2000 - 3000 microns or 78 - 118 mils. The ideal DFW (deposited film weight) would be between 75 microns (3 mils) and 100 microns (4 mils). Personally I would not worry if the DFW rose to 120 microns (app 5 mils. My main concern is your use of iron phosphate as this would give minimum protection to the substrate should the powder film become damaged.

Terry Hickling
Birmingham, United Kingdom
November 16, 2010

Yes, that should read mils. Thank you for pointing out my error.

Rollin Heide
- Manitoba, Canada
November 17, 2010

---

November 22, 2010

Thank heavens for that.
I had visions of powdercoaters coating, recoating, recoating ad infinitum.
Maybe you could look at a Zn Al base mtl then a Zn Phosphate pretreat then your polyester tgic finish coat.
I think your film build will to a degree depend on Colour selection.
Safety Yellows, Oranges & Reds are notoriously translucent since the abolition of lead pigments.
Generally one would aim for ~80 microns but with these colours, dependent upon Powder quality you may need up to 130 microns.
Hope this helps.
Regards,
Bill

William Doherty
Trainer - Salamander Bay, Australia