How do I make aluminium roof sheets look old and rusty?

You could have just bought old second hand ones!!!

If you can get clear enamel paint and crumble rusty metal in it (or something resembling rust/oxidation)

Then paint patches of this on the sheets

Soak them in salt water

Aluminum sheets do not rust. Your pictures show corrugated sheet metal. If you're using it on a roof, you may get in trouble with leaking if you try to rust it prematurely. That said, a friend of mine used the corrugated metal as wainscoting in her country kitchen. She used muriatic acid to rust the areas she wanted.

Sand the area that you want rusted and wipe clean with a damp cloth.Then cover the galvanized metal with Lysol Toilet Bowl Cleaner that contains bleach. when you have the areas covered place in a safe place outside (out of the reach of children & pets) and leave it exposed to the elements for at least 4 hrs or overnight. When times up, rinse the solution off with water and allow to dry. Hopefully, your metal will be rusted and have an aged appearance! I got these directions from a post done by The Graphic Fairy. I hope it works!

muratic acid does the trick!

use toilet bowl cleaner. let sit. hose off

Try vinegar, it removes galvanized coating, and it's a lot safer than oven cleaner and better for the environment than a number of the suggestions. If you try using Muriatic acid, it might work but DO NOT breathe those fumes, they are very caustic to lungs!

If they are really aluminum they won't rust

Are your panels actually tin, rather than aluminum? If so, there are many methods to create rust, some quicker than others! :-)

Thanx SO much all that have answered my question. It has been very helpful. Tx again.

Michele, Cape Town, South Africa

Hi Michelle! I previously suggested the process used by The Graphic Fairy but I have since found the one that I couldn't find until now and I much prefer!

Mix together in a spray bottle 1 cup Hydrogen Peroxide, 1 cup white or cider vinegar and 2 Tbsp.salt.This mixture can be used on any metal for an aged patina, like Brass, Copper, Galvanized Aluminium or Steel.If you're aging small items like keys or hardware, you can put the mixture in a bucket and let the items soak overnight. Also, I keep the leftover mixture and just add more salt to it before reusing! It works like a charm!

I have used Hydrogen peroxide, vinegar and salt mixture to rust a number of things successfully and also recommend it.