ask aluminium Forum

Aluminum Diamond plate is most commonly seen on the backs of trucks as storage units and tool boxes. Usually it is silver, but some people do like to paint it to match the rest of the automotive decor or just to suit their taste. You can paint diamond plate aluminum, but it needs to be appropriately prepped first.

Step 1
Take the tarnish off. Aluminum will have a bit of tarnish on the top, and this needs to be removed. Using your toilet bowl cleaner, scrub it on with the brush and rinse it completely.

Step 2
Allow it to dry. You can wipe the diamond plate aluminum off with a dry rag, but you still need to let it sit and air dry as well. Give it ten to twenty minutes in a warm, dry atmosphere to make sure it is completely dry. It needs to be 100 percent dry before the next step.

Step 3
Spray paint the diamond plate aluminum. Start from the upper left corner and work your way down and across to the lower right corner so that you have covered the entire diamond plate. This initial coat will serve as a primer. You do not need a separate primer from the spray paint itself because you have removed the tarnish and made the plate amenable to painting already.

Step 4
Let the paint dry. This can take several hours or more if the air is humid. Do not touch or move the plate until the paint is completely dry.

Step 5
Add second coat of spray paint. Move in the same pattern as before, from the upper left to the lower right. This coat will add brightness and durability to your painted diamond plate aluminum. Allow the spray paint to dry again, then you can add a third coat if you wish, but it is not necessary.

Aluminum begins to form an oxide layer immediately on exposure to air, if it's not already present. This is what helps keep corrosion down.

Options:

1) Don't paint it. You don't need to - aluminum won't corrode outside of caustic environments (generally) anyhow.

2) Sand or brush the oxide layer off, wipe it down immediately with mineral spirit or denatured alcohol, and spray down as soon as it's dry with acid-etching primer (and you'll usually end up with an oxide layer anyhow.)

3) Anodise. Anodising is simply a special form of an oxide layer on the surface - it can be made to take a colour (many colours are available,) and you can make the oxide layer harder than the base metal (a MIL-spec hard anno on aluminum that has been mildly knurled will make a part that can be used to literally saw through an aluminum plate. Not sheet - plate!)

4) Powdercoat. Powdercoating isn't as hard as a good hard anno, and it's an applied finish (instead of a surface-layer conversion,) but it's stuck on better than most epoxy finishes.

I'd honestly say that option #3 is your best bet if a specific colour is desired, with #1 or #3 (clear anno) for metal "in the white." Powdercoating aluminum is reasonably effective, but anno is a better option.

Depending on the size of the parts and what means you have available, you can get anno or powdercoating kits to use at home. You can also fully DIY your anno setup with a little research. (Powdercoating requires heat, so you will be limited by the size of the oven you have available.)

Another option - if you need a muted colour - is an interesting PTFE/Moly finish that is available for use with firearms parts. I've seen it through Brownell's, and I've been wanting to get it for my refit to use on certain parts (mainly underbody stuff - brake calipers, backing plates, axle covers, and the like.) The colour selection may have expanded by now, and it's something that may bear looking into, depending on your needs.