I got a weird question the other day. Is it OK to paint an AC adapter? Or: Can you paint an AC adapter?
I wouldn’t. For a couple of reasons.
My first concern is safety. Liquids getting in the adapter are OK as long as they dry out completely before you plug them back in. But since most AC adapters don’t open, you don’t really have any way to verify that they’re completely dry. All you can do is let it sit in a dry, warm place for a day or two, and hope.
Beyond that, the biggest difficulty is trying to get the paint to actually stick to the adapter. Plastics are notoriously difficult to paint. The paint will stick for a while, but eventually will start to peel and flake off. And it would be difficult to prep the plastic case for proper painting.
Not only that, AC adapters tend to run hot, and that heat will cause the paint to degrade more quickly. That means more peeling and flaking, and depending on the amount of heat, it also means discoloration.
So, for those reasons, I’d just leave an AC adapter alone. It will look a lot better unpainted than it will look after 6 months of being painted.
Cleaning an AC adapter
If an AC adapter looks grungy, I would clean it instead of trying to paint it. Unplug the AC adapter, then wipe it down with a soft, slightly damp cloth. If it has stubborn dirt, you can use a little bit of detergent. Let it dry before you use it again. Once you get it clean, it’s going to look as good as it can.
If you just can’t make it look nice, here are some tips for replacing AC adapters with newer ones.