gthomson Thanks again for the great info. Dave, how long should it soak in the vinegar? I hope the baked goods didn't taste like spray paint after that!
Thanks again for the great info. Dave, how long should it soak in the vinegar? I hope the baked goods didn't taste like spray paint after that!
With vinegar, an hour or so ought to be enough. When (if) the metal changes color, usually it goes white, it has got enough etch. It isn't critical, leave it in over night and no harm done.
David Starr www.newsnorthwoods.blogspot.com
gthomson thanks all, will do the wash/rinse and I have model primer so hopefully that works. Don't think I wasn't to risk the wife's wrath using the baking process but I appreciate the advise.
thanks all, will do the wash/rinse and I have model primer so hopefully that works. Don't think I wasn't to risk the wife's wrath using the baking process but I appreciate the advise.
Yup, I used our kitchen oven once for an MDC boiler, and the smell ratted me out. The pastry queen was not impressed!
Step 1 is surface preparation, namely getting the surface squeaky clean so the primer will stick to it. For a Zamac diecasting, hot soapy (Dawn dish soap) water works. You can go with more aggressive laundry detergent or even TSP. The Zamac doesn't care. Paint doesn't like to stick to metal and it needs all the help you can give it in the surface prep department. Then you want to etch the surface to give the metal some tooth for the paint to grab onto. I use supermarket vinegar. Others use any mild acid they might have. Don't mess with the strong mineral acids, battery acid (sulphuric acid) or nitric acid. They are so strong as to be dangerous to handle. You can pickle before or after washing. Finish with a good hot water rinse and a good long dry. Don't touch the model with your bare hands after washing, the finger prints can show thru the paint.
For Zamac, I recommend the rattle can auto primers from Krylon or Rustoleum. These are sold to professional car mechanics who use them to touch up or even repaint car parts, which may be sorta greasy. So they have the best stick-to-metal chemistry known to man. The model primer paints are usually just the run of the production line model paint in a primer color. The rattle can auto primers are the best for stick and for coverage. And they dry dead flat and any kind of top coat sticks beautifully. Use light gray primer under light colors like yellow, use dark gray under dark colors, and red under red.
After applying the primer (auto primer works well), I bake the piece for 20 minutes at 250 degrees. You might have to negociate this with rest of the household if you use the kitchen stove. I bought a low cost stove for this purpose. Try not to touch the outside shell during the process. Good luck!
Simon
I've done diecast locomotives using the pickling method and not using it, and saw no difference in paint performance.I think that a good wash with dish detergent to remove oil and grease, and a good rinse will be just as effective.I used Floquil grey primer on mine, but any non-filler type automotive primer should work just fine, too.For finish paint, I've used both Floquil and PollyScale (both discontinued) with good success, and once the primer is on and fully dried, pretty-well any paint should work well.
Wayne
wash it with dishsoap , dry pickel in white vinagar and distilled water, coat with black automotive primer .
Does anyone have any advice for painting an old Bowser HO scale diecast metal trolley? Should I sand or clean first before applying a primer? Do I need to sand and polish the primer after I apply it?
Any help would be appreciated.