Authoritative Answers, Fun, & Aloha -- no cost, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Home /
Site 🔍
pub     mobile?
Metal finishing Q&As since 1989


The seal coat on anodized parts is inhibiting an epoxy cure


Our problem is:

We adhere a tiny aluminum bobbin to other tiny aluminum parts in the manufacture of industrial instruments. The parts are color anodized (sulfuric). Due to a recent juggle in the sourcing of these parts, we are having them anodized at a local plater instead of the vendor's shop. The problem is that at some point, the epoxy will not cure these parts any more. It is a special non-hygroscopic, one part, thermally cured adhesive. I believe that the new plater is using a different sealing method, and a component of the seal coat (probably the surfactant in a nickel acetate solution) is a cure inhibitor to the epoxy. We have had this issue once before with an older "lime" finish on aluminum and this epoxy. We have had this epoxy work with color anodized parts for over a year now and believe the epoxy is not the problem (not 100% sure about this batch of epoxy). The epoxy mfg. claims to have this batch of epoxy work with our parts by cleaning them with acetone [on eBay or Amazon (adv.)]. I haven't been able to repeat that with many attempts. I have tried numerous solutions to treat the parts, alcohols, solvents, acids, etc. no success. This epoxy will cure Iridited parts. or bare parts. I may have the parts stripped and re-anodized with a boiled DI seal or no seal. Any ideas?

Mfg Engineer

Edward Doherty
instruments - Coral Springs, FL, USA

I believe we have a solution on this problem. Although we have a new anodizer for many of these parts, we still have many styles in stock from the original finisher. The epoxy would not cure those parts either. It is true that any high ph contaminant or moisture will be a cure inhibitor for this epoxy, but our current dilema cannot be caused by a finishing issue. What had happened was this batch of epoxy had been refrigerated to extend shelf life - that was a mistake. Every time it got opened, moisture would condense on the surface of the epoxy and dissolve into the mixture. This had a cummulative effect and created the cure inhibitor issue only on anodized finishes. A new batch of epoxy has been ordered, so problem is not 100% verified solved, but we are confident in it.

Edward Doherty
instruments - Coral Springs, Florida, USA

In either event, you wil get much better adhesion if you will bond the epoxy to UNsealed anodizing, then go back and seal after the epoxy has cured.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina


Can you tell me what type of epoxy you are using for this application.
I have a similar need for an epoxy coating on anodized aluminum.


Steven Roehlk
- Indianapolis, IN, USA

(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:

Chemicals &
& Software

About/Contact  -  Privacy Policy  -  ©1995-2024, Pine Beach, New Jersey, USA  -  about "affil links"