Industry specs for powder coating thickness and testing methods? p.2

A. There's not much relationship between those factors and coating thickness, though conveyor speed has some impact, but only where a conveyor is used (not all powder coating is done with a conveyor).
Varying the curing temperature doesn't change the thickness.

If you wish to change thickness of the coating, try varying gun parameters.

A. Well, this item is usually referred to as a "cure schedule".
Essentially it means time at metal temperature and is usually represented graphically.
There is very little change with varying coating thickness.
Hope this helps.
Regards,
Bill

A. Hi L M. When you say "structure finish", my understanding is that you are referring to what we call "texture finish" in the USA. Unfortunately, I'm not fully sure what your question is. You mention DFT of 60 to 180, presumably microns (1-1/2 to 4-1/2 mils)...

If you are asking whether that 3:1 range an acceptable variation, we'll have to wait for an expert with experience in structured coatings to chime in, but meanwhile my understanding is that the answer is "No" -- i.e., that for structure you will need a reliable minimum thickness of 75-80 microns, and that going much over 120 microns will be an invitation for orange peel. The powder vendor's technical data sheet probably has a suggested DFT range.

Regards,

A. TGIC resin polyester powders are normally coated at 60-80 microns.
If you are applying a Pb free Yellow / Orange /Red it might be advisable to knock this up to 80-100 microns for opacity.
Much above this could lead to Orange Peel.
Hope this helps,
Regards,
Bill

A. Hi Shrikant. The thickness depends on the type of powder (for example polyester thermoset vs. nylon thermoplastic); and the minimum thickness may be specified by the application, but as you've read on this page several times, typical polyester thicknesses are 30 to maybe as much as 80 microns.

You have to get operating instructions for a particular brand of thickness tester from its supplier. But the operating manual for the unit in question appears to be available on the web at http://www.metravi.com/PDF2/CTG-01.pdf

Regards,

A. The thickness is depends upon various factors like application method, use of the parts, chemistry of powders etc. But normally we can say the thickness 30-80 microns.

A. Hi James. Although PVDF powder coating is certainly possible, my understanding is that most of the 'super-durable' architectural coatings are usually multiple liquid coatings, not powder.

I think proper pretreatment and electrocoating before powder coating are far bigger contributors to the durability of powder coated surfaces than the thickness of the powder.

Regards,

A. Hi Lavjeet. I don't think the thickness of the powder coating has a lot of bearing on this. Proper phosphatization, plus electrocoating before powder coating, plus UV resistance if used outdoors, are probably far bigger indicators of longevity than the powder coating thickness.

Regards,

A. Our company declines work where the customer asks for a single coating of powder applied polymer on steel where the use is outdoors. Our reasoning is that this is a specification bound to fail, and the coater will get the blame not the specifier! All paints are porous, but that porosity varies from one coating type to another. Without some form of corrosion protection coating underneath, the first scratch, nick of crack in the coating and corrosion starts and spreads. It's almost inevitable that a steel item will get some impact and any damage to a coating will leave the steel open to corrosion. The thickness of that coating doesn't change this situation. Geoff Crowley Crithwood Ltd. Westfield, Scotland, UK A. Ted is correct, I currently work on a coil line, our coatings are typically half of what your would find on a post paint liquid line which is again lower than many powder lines. Ronald Zeeman Coil Coating - Brampton, Ontario, Canada

A. Hi Mohan. William Doherty suggests in the first response on this thread that 5 mils is probably too thick for good polyester coatings. What type of powder are you applying, and why does it need to be 5 mils thick? Thanks.

Regards,

A. Generally, 5 mil is too thick for powder coating products. Powder coating manufacturers suggest a thickness <4.5mil, but still, some industries prefer a thicker coat. In our extrusion plant, we usually provide 3 mil for powder coating aluminum profiles. But there are indeed some clients ask for 6 mil thick.