unique1

Topic: Best aluminum cleaner for shutters?

I'm about to powder coat some shutters a black wrinkle and i need to find the best pretreatment for them. I have alumibrite,phosphate and a few others out there. I'm looking for something that i can dip them into and either it evaporate off or spray off with the water hose. 

dpatterson

Re: Best aluminum cleaner for shutters?

Unique1:

To correctly prepare aluminum for powder coating it should be cleaned to remove the oxides on the surface and then pretreated with a conversion coating which improves the paint adhesion and minimizes corrosion.  Are you doing the shutters for a customer and are you providing any type of warranty on how long the paint will last.

For shutters especially along the coasts or in very humid climates I recommend a non-chromate conversion coating designed for aluminum.  The majority of these can be applied to a clean oxide free surface and allowed to dry in place by immersion or I have customers applying this material with a pump up garden sprayer.  The cleaner will need to be rinsed off the metal prior to applying the conversion coating.

Products such as these are available from most of not all of the major pretreatment suppliers.  You mentioned you have a phosphate, I recommend you start by talking to the supplier of that material.  If they do not have a product then ask your powder supplier if he or she can recommend a pretreatment supplier for you. 

One more item for you to be aware of; by applying a conversion coating you become a catagorial discharger and will need to look at waste water issues.  If you are a very small operation then you can probably just evaporate any process solutions but check with someone in your area.

I hope this has helped you out.

dpatterson


   abrite.jpg

DustinGebhardt

Re: Best aluminum cleaner for shutters?

I second what dpatterson said.


If these are old shutters that you are trying to rework, then be sure to get all of the old oxide off.  Media blasting can help if they are severely corroded.  However, anything that is already oxidized will probably be pitted at the base metal, but perhaps the wrinkle will hide them.

-Dustin Gebhardt,
CEF
Plating Engineer
Danaher Tool Group
Gastonia, NC

unique1

Re: Best aluminum cleaner for shutters?

Yes, these are for a customer. We are a small company that just started powder coating about 1 yr. ago in lower AL. I gave him a waranty on the "workmanship" and quality of the work. As far as the color fading and what knot, no. I have got in touch with a chemical place locally and they recomended something called Big A. He said it has some type of acid too. 

unique1

Re: Best aluminum cleaner for shutters?

I recommend a non-chromate conversion coating designed for aluminum. What is that?

Paul Fisher

Re: Best aluminum cleaner for shutters?

Chromate conversion coating is a type of conversion coating applied to passivate aluminium, zinc, cadmium, copper, silver, magnesium, tin and their alloys to slow corrosion. The process uses various toxic chromium compounds which may include hexavalent chromium. The industry is developing less toxic alternatives in order to comply with substance restriction legislation such as RoHS. One alternative is trivalent chromate conversion which is not as effective but less environmentally damaging.

Chromating is commonly used on zinc-plated parts to protect the zinc from white corrosion, which is primarily a cosmetic issue. It cannot be applied directly to steel or iron, and does not enhance zinc's cathodic protection of the underlying steel from brown corrosion. It is also commonly used on aluminium alloy parts in the aircraft industry where it is often called chemical film, or the well known brand name Alodine. It has additional value as a primer for subsequent organic coatings, as untreated metal, especially aluminium, is difficult to paint or glue. Chromated parts retain their electrical conductivity to varying degrees, depending on coating thickness. The process may be used to add color for decorative or identification purposes.

Chromate coatings are soft and gelatinous when first applied but harden and become hydrophobic as they age. Curing can be accelerated by heating up to 70Ā°C, but higher temperatures will gradually damage the coating over time. Some chromate conversion processes use brief degassing treatments at temperatures of up to 200Ā°C. Coating thickness vary from a few nanometers to a few micrometers thick.

Paul Fisher's Website