Summary for 13.5 pH seal requirement Discussion
13.5 pH requirement for seal on anodizing is discussed as a request for a sealing system that can meet a higher pH spec and still be difficult to strip. Bryant Tokarz asks whether any U.S. supplier offers a seal additive that will satisfy the 13.5 pH requirement, noting he has heard of a German or European source but has not found one in the States. The only answer in the thread comes from an unnamed contributor, who suggests looking at nickel fluoride impregnation sealing rather than hydrothermal sealing such as boiling water or steam. The answerer notes these are often called "cold sealing" systems and points out a practical advantage: defective coatings can be very hard to strip in the normal sodium hydroxide stripper, which may be the property the requester is after. No specific U.S. supplier is identified in the thread.
Q. We are hearing a lot requests for bumping the seal requirement on Aluminum Anodizing up to 13.5 pH. I have heard that someone in Germany/Europe is meeting this requirement but I have not found anyone in the states who can supply a seal additive to meet this requirement. Does anyone know if someone is producing a seal that will meet this in the US?
Bryant Tokarz
– Murfreesboro, Tennessee, USA
April 3, 2012
A. I would consider sealing systems which use nickel fluoride impregnation sealing rather than hydrothermal (boiling water or steam) sealing. These processes are often called “cold sealing”. One of the problems that arise from using them is the great difficulty in stripping defective coatings in the normal stripper, sodium hydroxide – a property you are seeking.
Harry Parkes
– Birmingham, UK
April 11, 2012