Should I sand the primer, or undercoat then sand on primed doors?


27 Oct 2003
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United Kingdom
Hello again!

I've got Howdens primed doors that have a routed detail.

In many places the router has left some roughness - you know the kind of hairy edge you get when you cut something like hardboard. It's in most of the rebates, sometimes the whole length or width of the door. (Tried to photo it but can't get close enough).

I'm sanding with P320 Saitac sandpaper folded over the edge of a wide scraper, to get into the rebate and target the roughness. In places I'm getting back to the wood.

Am I best to sand the primer like this? Or do a coat of undercoat, then sand? (Am using Bedec water-based undercoat.)

And do I have to worry about the odd bit of primer missing, or will the undercoat bridge the gap? None of the bits of bare wood is more than 1mm, and probably still has a smidge of primer on.

Thanks folks
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I would have expected only a light sanding is required, enough to get a 'key'.

The roughness does of course need special attention, and bare wood should be primed. An oil-based primer should seal this kind of wood better IMO. If you do skimp on the priming, be sure the undercoat fully covers the bare wood before the final top coat, as you risk seeing these spots showing through the finish.
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