No registration or passwords; no pop-up ads -- just aloha, fun, & answers.
(as an eBay Partner & Amazon Affiliate earns from qualifying purchases).
Home /
T.O.C.
Fun
FAQs
Good
Books
Ref.
Libr.
Advertise
 
Help
Wanted
Current
Q&A's
Site 🔍
Search
pub  Where the
world gathers for metal finishing
Q&As since 1989





-----

Historic tin roof refuses to allow primer to stick


October 31, 2010

Hello: I live in Tennessee's oldest town. I have been restoring a turn of the century cottage, which has what I believe to be the original tin shingle/plate roof.
I am in a race against winter to repaint the back end ( south weasterly end) of the roof. It has got me stumped.
Originally, I followed Sherwin Williams advice: scraped off any lose paint, used Ospho rust neutralizer, rolled on Ken Kromic universal, an alkyd metal primer.Then I applied a dtm acrylic.
Within less than a year it started to peal off both the primer and paint.
Sherwin Williams gave me a generous quantity of primer/paint.
But I am confused. There appears to be a greenish blackish substance covering the shingles along with some rust spots, after I scrape the loose paint.I have sanded down to shiny metal to get rid of any rust and this covering. Is this substance my the culprit?
Could the original Ospho or primer have reacted weirdly? What do you think, I am pulling my hair out. I do not want to apply the primer if it is wrong for the task. Brian in Jonesborough.

Brian Mills
historic home restorationist - Jonesborough, Tennessee, USA



November 1, 2010

Hi, Brian

I'd like to hear from an historian or a metals conservator on this, because I am wondering if this might be a lead-tin (terne plate) hot dip coating rather than tin or zinc. Most acids/etches will not activate lead, but only make the adhesion worse.

If you google for terne plate, you'll see that there are some experts in the subject, and they may be able both to tell you if you have terne plate, and how to get adhesion on it.

If that doesn't work out, you might need a fluoride based dip to get adhesion, and this is dangerous stuff. If you have a truck-wash in the area, you might see what the operator has to say about the whole subject because they sometimes used hydrofluoric acid based washing solutions on the aluminum and stainless steel tankers. Good luck.

Regards,

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




(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"