50044

Required leaching practice for anode bags and filters  

September 19, 2008

With todays quality of anode bag material is it necessary to leach these prior to use in a sulfamate nickel plating bath? What might be the ramifications if you don't? Also, we use 1 micron filter bags for our EN filters, Same question on leaching.

Jerry Wendt
Manufacturing Engineer - Manitowoc, Wisconsin, USA

They might be just fine as is, but....I once got in serious trouble using non-leached bags. It seems they were sewn with a silicone thread lubricant, which caused enormous problems in plating.

Wash them in hot water and detergent in a heavy duty washing machine. Twice.

Jeffrey Holmes, CEF - Spartanburg, SC, USA

Jerry,
The best thing to do is to contact your anode bag manufacturer and ask them. Some of todays anode bags come "pre - laundered" with no leaching necessary. Some dynel or synel bags still contain sizing material which should be leached out with a 10% solution of sulfuric acid, then rinsed well. Again, see what the mfg. says.

Mark Baker
Process Engineer - Syracuse, New York

I agree with Jeffrey. Although manufacturers claim you don't need to leach the bags it does lead back to the old saying "an ounce of prevention....".

I generally suggest, for your application, leaching the bags in 5% by volume sulfuric acid for 24 hours. I would also add some of the wetting agent (anti pit) you may be using to this leach solution. Then water rinse throughly.
The reason for the use of the wetting agent is because of the tendency of the polypropylene to absorb some of the wetting agent from the solutpon.

Gene Packman
- Great Neck, NY