Heavy smoke damage from a trash can fire on white hardboard….

Has anyone ever had success removing soot/smoke residue from white hardy board? If so what product and method worked best? I haven't used the power washer yet bc I read it only makes it worse.

Tried the vinegar route and a couple other products, but it only smeared mostly.

Any suggestions or successes appreciated.

If it's inside on a wall in a room, if you have an ozone machine, it will help break those molecules down and you can clean it easier

Outside. Hardy board. White.

Vinegar just smears the soot. It's thick. I'm looking for something to break it down and clean it.