White Powder/Salts on Anodized Aluminum

A. Aluminum How-To lists about 30 different causes for "white spots" and smut. By far the most frequent is calcium salts left behind from the seal, which you see only after the water evaporates. The second most frequent cause is galvanic corrosion usually between titanium rack sand stainless tanks/heaters. Come back to us with more information on the racking, tank materials and whether or not the dye and seal are made up with deionized water and whether tap water is dragged into the dye and seal. This problem CAN be beat.

A. Hello Lee. If you are saying that the parts are free of dust until your customer starts engraving them, then the engraving process generates dust, it sounds like what one would expect. The anodized surface is not metallic aluminum, but is a ceramic comprised of aluminum oxide and hydroxides. Depending on the engraving or machining methods, it may come off as a powder or grit rather than adhering to the aluminum 'chips'.

You may want to insure that your anodizers are not using chrome sealers which could contain hexavalent chrome (they probably aren't for signs and nameplates). It is not safe to inhale significant quantities of any dusts regardless of their chemical makeup -- lungs are very delicate micro-machines -- but aluminum oxides comprise more than 10% of the earth's crust, so the dust is probably not a hazardous material in my opinion (additional opinions and citations are certainly encouraged).

Regards,

A. I guess Lee's wording was confusing because 3 readers have read it 3 different ways :-)

My understanding was that Lee shipped the plates to a customer, and when the customer engraved them it generated a dust which the customer was concerned about.

Speaking personally, I have had emphysema for decades, which I attribute 90-95% to the fact that I smoked. But I also know that I never had the common sense to be careful to avoid inhaling dusts from woodworking, rust removal sanding, dusty attic visits, power lawn mowing, blowing the dust off this & that, smoke from candles blown out, etc. Now that my lungs are very bad, I can immediately feel and know how toxic it is to keep re-lighting & re-extinguishing the candles on birthday cakes for the perfect photo ... but I don't recall even once in my life our regulatory agencies warning us to be mindful about this *general* crap we should not coat our lungs with :-)
I feel that our regulatory agencies do a bit of a disservice concentrating on 'hazardous material dusts' because it lets them and us point the finger at "the bad guys" while removing people's focus from what seems to me is the far more important issue of warning people to try to avoid inhaling any smokes or dusts :-)

In my local TV area, I hear ads from NYC attorneys every night talking about widespread cancer in residents living in the 9-11 area. I don't think it's nearly as important to ascertain exactly what size and material of dust resulting from the collapse of the skyscrapers is causing cancer as it is to simply recognize that excessive inhalation of most such dust is a problem.

Perhaps it's possible to do this machine engraving with at least a continuous water wash to capture the dusts.

Regards,