Aloha, fun & authoritative answers -- no cost, no registration, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Home /
T.O.C.
Fun
FAQs
Good
Books
Ref.
Libr.
Adver-
tise
Help
Wanted
Current
Q&A's
Site 🔍
Search
pub  Where the
world gathers for metal finishing
Q&As since 1989



-----

Should we bake the paint?




 

Q. My company remanufactures two-stroke aluminum block engines. The engine block components are disassembled and blasted clean of all grease and paint before the remanufacturing process. The bare aluminum of the assembled engine is then repainted back to the OEM color. Right now we use high temperature engine enamel from a can. We are looking to improve the process so that we get a harder finish that sticks to the aluminum a little better and has a longer life. One of the current drawbacks now is the time it takes for the paint to harden. It also seems to peel away once it is scratched.

Some questions we have are:

1) Should we be spraying from a gun rather than a can? We have looked at the economics and it really doesn't seem that much cheaper, only faster. Are we missing something? How much should we pay for a paint that will work in this application.

2) Should we be priming the bare aluminum? What processes should we consider. Please keep in mind we are working with an assembled engine that cannot be dipped in water or other cleaners/solvents.

3) Should we be baking the paint to quicken the drying process. Drying is not a problem in the winter, it's only an issue in the summer when the humidity is high. The operating temperature of the paint needs to be rated for about 250 to 300 °F. If we bake, we really cannot exceed a skin temperature of about 150 °F.

4) Do we need to use accelerators or hardeners?

5) We currently paint in a 10' x 20' paint booth.

Thanks,

Greg Pickren
- Clearwater, Florida


A. Try painting the block while it is hot!

A number of years ago I worked in a powerhouse on the DEWLINE. The engines were 671 Jimmy diesels, possibly the dirtiest engine ever made.

The powerhouse looked like new. Any grease was wiped off, and paint was sprayed on the running engine. The spray can paint bubbled a bit, but the end result was a fresh new look. The paint never seemed to peel or scratch!

Richard Trower
retired - O'Fallon, Missouri, USA


2007

A. For engine painting we can do that by
1. Clean surface of parts by
1.1 sand brush or sanding
1.2 solvent wipe off
1.3 steam cleaner [on eBay or Amazon]
2. Blow off surface until clean and wipe off again by tack rag (sticky cloth)
3. To spray special primer (for aluminum) on the parts
4. To spray top coat (2k type)
5. Are finished and no need to bake.

Arkom Salikarin
- Bangkok, Thailand




Q. I need to finish a small sheet metal box. I've tried painting with car paint but it scratches very easily. Can I bake the paint to make it harder? How is this done?

Thanks,

Joe Rogers
hobbyist - Calgary, Alberta, Canada
2003


A. Hi Joe. If the paint was meant to be baked, it must be baked. If the paint you selected was not intended to be baked, it should not be. I suspect that lack of pretreatment and primer is why the paint scratches too easily. Ideally the sheet metal should receive a phosphate pretreatment or at least thorough cleaning followed by naval jelly [on eBay or Amazon] or rust converter [on eBay or Amazon] . If this is a hobbyist application where that isn't possible, second best is shot blasting. If that isn't possible either, then really thorough sanding or thorough cleaning followed by a Self-etching primer [on eBay or Amazon] . Good luck.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 29, 2013




(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:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


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