Gregg,

What you are seeing is not uncommon. I found this same issue with pink poly bags several years ago.  What I found is that not all pink poly bags are created equal, and the difference is truly in the creation, regardless of any MIL spec certification.

The mil spec for the static dissipative poly bags (usually pink, but not always) is MIL-PRF-81705 Type II.  Turns out there are two common ways to get a bag to meet this spec:

1) Coat a poly bag with a static dissipative coating.  This is apparently the prevalent method, largely because it is the cheapest.  The downside is that the surface treatment often leaves an oily film on the bag, and consequently on items placed IN the bag.

2) Make a bag from static dissipative plastic polymer.  The dissipative properties on this type come from conductive material (I believe it is carbon or carbon-based) impregnated and literally molded into the bag material.  These materials are NOT a surface coating and leave NO oily residues.

We were able to "solve" this issue by limiting purchasing to a qualified vendor listing, and those vendors must meet the following criteria:

- ANTI-STATIC PER MIL-PRF-81705 TYPE II (COFC REQD)
- COLOR PINK
- AMINE FREE AND NON-CORROSIVE
- IMPREGNATED PLASTIC MFG PROCESS
- FREE OF PHYSICAL AND CHEMICAL (OILY / STICKY)
- CONTAMINANTS.
- DATE CODE AND LOT NO MARKINGS ON BAG DESIRED

We also inspect for all of these criteria at Incoming Inspection for each receipt of bags.

Your purchasing people will grumble because these requirements will drive costs up and also make it harder for them to source.  It takes quite some effort to find distributors who know anything at all about the method used to make the bags they are selling, or to even get them to find out for you.  Ultimately though, if they are unwilling to help you out, you probably don't want the risk of doing business with them anyway.

Overall, I found it is still cheaper to highly screen sources of supply for Type II dissipative bags than simply banning outright and using Type III shielding bags across the board, which was one of the solutions we initially considered.

Good Luck.

Kevin Glidden
Manufacturing Engineer
Astronics Luminescent Systems Inc.

-----Original Message-----
From: Gregg Owens [mailto:[log in to unmask]] 
Sent: Tuesday, March 30, 2010 10:04 AM
To: [log in to unmask]
Subject: [TN] ESD Cap Plugs

Dear TechNet:

There has been discussion on the use of "pink poly" for ESD prevention on flight hardware. An expressed concern has been the chemicals added to the surface of pink poly can potentially contaminate our products with the residue pink poly leaves behind. I have posted a picture of one of our boxes which have both the pink poly and black ESD style of cap plugs. What are any of your experiences with contamination associated with using pink poly? As always, thanks,

Gregg Owens
Technical Writer - Avionics
Space Exploration Technologies Corporation
1 Rocket Road | Hawthorne | CA | 90250
310-363-6533 | [log in to unmask]


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