powder coatings

[niksmith]

I am reading more and more these days on powder coatings .The doubt which I have is whether application in the traditional manner ie,spraying the coating over the substrate in a liquid form is inferior in terms of physical and chemical properties with respect to a coating applied using the powder coating technique assuming both are having the same resin base ??

Any input is welcome .

Best Regards,
NIk Smith

 

[Demon3]

Firstly I am not sure there will be a difference but if there were one I would expect the liquid spray to be better because the low viscosity liquid will wet out the metal substrate better and therefore tend to give better adhesion.

 

[CoryPad]

Since your question is general in nature, the general answer is that both liquid- and powder-based coatings can have very good properties. One reason to use powder-coating is for thicker coatings - it is hard to get large thickness from liquid-based coatings unless you apply it many times. Do you have a specific question? If so, you should be able to get a specific answer.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[niksmith]

Yes I have a specific question .Can this process of powder coating be used for coating hot glass ( at 700-800 degC) ? I have tried coating glass at the above said temperature but with the iquid based coating the glass cooled too rapidly and the powder did not adhere well nor was it possible to apply it to a thickness as to have an opaque coating .

best regards,
NIk Smith

 

[Demon3]

As you know rapid cooling will not be good for adhesion as the thermal expansion coefficient for the coating will be far higher than for the glass thus creating an interfacial force that aids delamination. Slower cooling will help a bit. One way to improve the adhesion to the glass is to use the appropriate silane coupling agent (from Dow Corning and others). This bonds chemically to the glass and to the coating.