Metal finishing Q&As since 1989

-----

What is the difference between hot press, cold press, and galvanized sheet metal

I run a retail picture frame and art store. I am renovating my store and I am using sheet metal to cover a few walls in my store. I have purchased some hot rolled steel 16 gauge, It seems like it is kind of "wavy" on the edges, and I may have a hard time getting it to lay flat against the wall. I have used galvanized sheet metal a few years ago and it laid almost perfectly flat. Is this hot rolled sheet metal defective? Should I try cold pressed sheet metal instead? Do you have any advice? Second, this may sound really stupid, but what product do I use to wipe down the sheet metal so I can get the dirt, grease, and minor rust off of it?

Melissa Baughman
using metal to renovate store - Aurora, Colorado, USA
2004

---

2004

First of all, when you refer to hot or cold rolling, that is referred to the method of how the sheet metal was formed. Galvanizing is a coating that is applied to sheet metal.

The galvanizing coating is non-oxidizing (does not rust) and is bonded to ordinary sheet metal.

As far as cleaning to remove grease and normal dirt/grime, the best liquid is acetone [on eBay or Amazon]. Be careful though, as acetone [on eBay or Amazon] will harm most surfaces that are not metal.

If your sheet metal is rusting, either you have a bad galvanized coating, or the material is not coated at all. The only true way to remove rust is to grind (or sand) it away, then coat the material with something that will seal out air (such as paint or polyurethane).

My experience with sheet metal is that if you want it to be flat, use cold rolled. I hope that gives you a little background and it helps your decision.

Tom Beyreis
- Wheeling, Illinois, USA

---

Cold rolled steel is rolled at room temp. while hot rolled is rolled heated.

Simon Dupay
- Roseville, MN, USA
2004