Home /
T.O.C.
FAQs
 
Good
Books
Ref.
Libr.
Advertise
Here
Help
Wanted
Current
Q&A's
Search 🔍
the Site
pub Where the world gathers for
plating, anodizing, & finishing Q&As since 1989





-----

Spot test on clear chem film





2005

What is the fastest test to verify there is chromate present on a clear chem filmed panel.

Need to know asap thank you all.

Jesse Santillan
- Sylmar, California



2005

Hmmmm. This a trick question. There is no such thing as "clear" chromate film. Yes, I know the MIL spec talks about "clear", but...chromium compounds are highly colored. No color at all = no chromate film at all.

Most people who buy and sell "clear" chromate understand that it is really pale yellow. Maybe very pale, but yellow nevertheless.

Some purchasers insist that their "clear" chromate have no color whatsoever. The shops who supply them do so in the same way as you make a very, very dry martini - just wave the Vermouth bottle over the glass...and just wave the parts over the chromate tank.

Sorry I can't be of more help, but if you have absolutely no color whatsoever, you aren't going to find any chromium by a test, because there isn't any. See if you can settle on "almost clear", and then you can tell by eye whether it is there.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina



2005

Having been around this industry for many years I have seen the development of conversion coatings. There indeed was once clear: this is done by leaching a yellow conversiion coating (dichromate) in an alkaline solution until clear. Here you have the reason Jeffrey says a little yellow: if you leach too long you don't know if your clear has any chromate left so most just leave a hint of yellow. (these have the highest corrosion resistance of clears) To further muddy the waters blue bright finshes are also referred to as clears and these came along years later billed as brighter, more appealing and less expensive as a single dip process. Now the above were all hexavalent, today there are trivalent finishes some of which can come out truly clear (generally these are designed as a base for yellow dye).

Gosh ain't this confusing.

Gene Packman
process supplier - Great Neck, New York



2005

You can find traces of Cr+6 by using kits that detect Cr+6 in water. If you see the violet color even if it very faint than you know you have chrome on the film. Make sure the panel is clean as the test is very sensitive.

Moshe Yaakov
- ISRAEL


none
finishing.com is made possible by ...
this text gets replaced with bannerText
spacer gets replaced with bannerImages



(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact    -    Privacy Policy    -    ©1995-2023 finishing.com, Pine Beach, New Jersey, USA