GOLD CHEMICAL CONVERSION COATING PER MIL-DTL-5541F TYPE II CLASS 3

[KENAT]

I have a question on the ROHS compliant type II version of this finish, is it still available in gold?

Our old note was just:

FINISH: CHROMATE CONVERSION COATING PER MIL-STD-5541 TYPE 1A (GOLD)

A vendor just supplied parts with clear coating to TYPE II. They were mistaken as having no coating, becase being clear it wasn't immediately obvious, and rejected. When contacted the Vendor implied that Type II was not available in gold, is this true (we're trying to get hold of their 'expert' but haven't managed yet)?

We'd like to keep the Type II as ROHS is a concern but also want Gold for primarily aesthetic reasons. My proposed new note is below (Class change is for ESD reasons).

FINISH: CHEMICAL CONVERSION COATING PER MIL-DTL-5541F TYPE II CLASS 3 (GOLD).

Google searches of web and this site didn't turn up a definative answer.

http://www.finishing.com/418/22.shtml

suggests to me it is available in gold. Looking at the standard itself it suggests gold is available but isn't explicit.

Thanks.

KENAT, probably the least qualified checker you'll ever meet...

 

[israelkk]

First, no mention of GOLD in the spec. This is just the color due to the compositions containing hexavalent chromium in Type I. In type II where the compositions containing no hexavalent chromium it is probably clear.

Here is a quote from MIL-DTL-5541F "Materials qualified under MIL-DTL-81706 produce coatings that range in color from clear/colorless to iridescent yellow, brown, gray, or blue".

MIL-DTL-81706 - Chemical Conversion Materials for Coating Aluminum and Aluminum Alloys

 

[KENAT]

Israelk, I realize it doesn't mention 'Gold' but does mention the iridescent yellow, which my guess is covers the color often referred to as gold.

What you say about the chromium content makes sense/rings a bell, I just wasn't sure if a 'died' version of the Type II was available that was goldish in color.

However, my colleague just got an early morning phonecall from the vendor in question and they confirmed that there isn't a gold Type II yet that they're aware of. So it looks like the note will be:

FINISH: CHEMICAL CONVERSION COATING PER MIL-DTL-5541F TYPE II CLASS 3 (CLEAR).

Thanks,

KENAT, probably the least qualified checker you'll ever meet...

 

[drawoh]

KENAT,

I have not been in this forum before. I just found your post by searching "mil 5541 rohs" on Eng-Tips Google. I did the same search on the

http://www.google.ca,

and the first hit is the following website...

http://www.finishing.com/444/84.shtml

Apparently, yellow is "the natural color of toxic, carcinogenic, hexavalent chromium". RoHS compliant coatings are approximately clear in colour. I am doing this search because some people here believe this to not be true anymore.

JHG

 

[KENAT]

Interesting, my searches at the time came up with a bunch of results from that site but not that particular one.

I can't remember where but I saw something recently which led me to believe there may be a Gold ROHS variant now but can't recall what/where.

I'll probably stick with clear until further notice.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[CoryPad]

There is a yellow dye for trivalent chromate conversion coatings. Contact big companies like MacDermid or Enthone or Atotech.

Regards,

Cory

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

 

[KENAT]

Cory, does that die work for chemical conversion onto aluminium? All my searches seem to show solutions for applying over zinc plating but most don't mention direct onto Aluminum.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?