Breathe easy! No registration or passwords; no maddening pop-up or floating ads :-)

Home /
Search 🔍
the Site
pub Where the world gathers for
plating, anodizing, & finishing Q&As since 1989


Pin hole problem



I am trainee in powder coating dept. We are doing powder coating on bathroom hanger made of mild steel. We first phosphate it then coat powder manually with epoxy powder, then we bake it for 10 min. Our main problem is pin holes come on the component. rejection is about 30 %. Please tell me the solution of this problem

Hemant Kumar Singh
international electron device limited - Ghaziabad, Uttar Pradesh, India


Mr. Singh,

I can't give you the solution, but I can give you the cause, pinholes are caused when two incompatible powders are mixed, or sprayed in close proximity of each other. If the source is airborne contamination, it will happen between the exit end of the paint booth and the entry of the oven. It's a good idea to have this area completely enclosed, If that isn't a possibility, make it taboo for ANYBODY to use spray paints or any type of aerosol anything close to the freshly painted parts. If it's a cross-contamination problem, it could be that the clean-up from whatever was being sprayed previously was not done properly. If the painter uses a powder supply hose for both polyurethane and epoxy paints, the probability of cross-contamination (and pinholes) is high on the suspect list. Now that you know the cause, the solution is to investigate! Good Luck.

Sheldon Taylor
Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina

(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 &
Consult'g, Train'g
& Software

About/Contact    -    Privacy Policy    -    ©1995-2023, Pine Beach, New Jersey, USA