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Early yellowing of clear anodized architectural extrusions

What could cause clear anodized (architectural)extrusions to yellow when exposed to exterior (only) after 1 year? Parts were class 2 anodized and sealed in mid temp (170F) non-nickel seal. Would certain adhesives sealants cause this?

CATHARINE BRYLA
sales rep - TORONTO, ONTARIO, CANADA
2003

Your reference to "certain adhesives sealants" if pretty vague, Ms. Bryla. Please tell us your hypothesis and the thinking that leads to it.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

Most probably inadequate sealing caused your problem of yellowing. Did you use any sealing additive for mid temp sealing? Correct type and amount? Did you rinse aluminum in demineralized water before sealing? Mid temp sealing not dependable to my opinion. Hot sealing is more secure.

Tim [last name deleted for privacy by Editor]
Aluminium Extrusion & Anodizing - Istanbul, Turkey
2003

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