Happy with the nitromorsing of a frame to get it raw but would it be OK left like that or is it best to have a clear coat put on the top?

Not looking to get it polished or anything, just want it ‘naked’ so I can match some part colours with the frame.

Depends what it’s made of. If it’s steel it will rust. If it’s alu then it’ll probably corrode as well. It’s really only Ti that you can leave really ‘raw’.

Leave it raw

“If it’s alu then it’ll probably corrode as well.”

Lots of bike companys make raw finished alu frames, inc. my Intense Spider, but it hasn’t corroded (not yet anyway). When/why does it corrode?

Bare aluminium corrodes to leave a thin aluminium oxide coating that supposedly prevents further corrosion.

If you polish some bare aluminium, and then just leave it, you’ll see it goes duller in a few hours / a day. Fingerprints will leave a mark.

The ‘raw’ aluminium frames you see are all clear anodised AFAIAA. This increases the thickness of the natural oxide layer, making it quite tough are looking reasonably good.

Raw isn’t always “raw”, it might well be a “raw” anodized finish. Salts are terrible for corroding alu frames, I’ve seen in where sweat gets under paint (from turbo use) and I’ve had road salt ruin the finish on a (poorly) anodised set of silver cranks.