You can e-mail your questions to Professor Hammer at, or mail to Professor Hammer. We'll print your name and city unless you request otherwise. Ron Covell has made many DVDs on metalworking processes, and offers an ongoing series of workshops across the nation covering all aspects of metalworking. Check them out online at, or call for a current schedule of workshops and their free catalog of DVDs and fine-quality metalworking tools. Phone 800-747-4631, or 831-768-0705. You can send a request by mail to Covell Creative Metalworking, 106 Airport Boulevard #105, Freedom, CA 95019.

Dear Readers,
Let's have a celebration! This is the 100th edition of the Professor Hammer column in CLASSIC TRUCKS Magazine! It has been a true pleasure to share my knowledge about metalworking with our enthusiastic readers over the last nine years, and I'm delighted that so many of you come to Covell Creative Metalworking with your questions about truck building. Don't hesitate to contact me by mail or e-mail with any questions on metalworking. You'll receive a personal reply even if your letter isn't published!

Q. I have a question about cleaning sheetmetal when MIG welding. Before welding, I always strip the area down to clean metal. After I make the weld, I use acetone on a small brush to clean the weld in preparation for painting. Is there something better? I'm concerned about cleaning the contaminants that form during welding, such as when using anti-spatter spray or those dark, burnt smoky spots that develop when tacking. I am under the impression that welding creates an environment that promotes rusting if the metal is not cleaned properly when the welding is completed. I am doing a patch on the cowl of my truck just below the windshield, and I want to minimize the chance of rust reappearing.

I've been using the Spoolarc Easy Grind wire for this job, and it has some interesting qualities. It's certainly easier to sand the weld than when using standard ER70S-6 wire.

Two last questions: What size wire do you recommend for welding the 18-gauge metal my truck body is made from, and do you prefer the "push" or the "pull" technique when welding sheetmetal?
Marc D'Estout
Santa Cruz, CA