Painting hardboard...

GrahamRounce · 24 Jun 2017

Yes, I'm afraid so! Not up to the usual level of fine finishes here, but still..
I want to paint some cupboard door panels, of new hardboard, the smooth side, with water-based emulsion paint. I don't want the hardboard to fluff up when it absorbs the paint, or indeed ever.
Should I seal it with something first? Something that won't cause fluff-up itself, but which the emulsion paint will stick to?
Thanks very much,
Graham

ED65 · 24 Jun 2017

I'll be interested myself in what anyone might recommend here, if anything.

First thoughts if you do need to prime or undercoat are BIN but that's expensive as hell and I'm not sure it's really needed TBH.

I've painted on hardboard many times in previous years in a different way to this (it's used as a panel material by artists) and even with untempered it didn't seem to me that it fluffed up that much when the first coat went on, but I was going to smother it with numerous further coats of the stuff so it might be that I just didn't notice.

Do you have an offcut or spare piece? The primer I put down first is actually of quite a similar consistency to emulsion so you might try it directly and see if it's okay.

GrahamRounce · 24 Jun 2017

Hi - yes, I've got plenty of offcuts, about half of it, unfort

. I can try that primer - what is it?
"Untempered"? Que? I fear the hardboard might absorb water more easily than oil.
I was thinking maybe some cheap spray lacquer, but doubt if the paint would stick to it.
I can experiment with all sorts, but I just wondered if there was a standard way, which would save me the trouble...
Thanks,

ED65 · 24 Jun 2017

Not sure if what I said was ambiguous but I was suggesting trying emulsion directly on the hardboard, not what I used to use.

That primer wouldn't be good for normal painting purposes as it's made for artists and priced steeply. If you saw what they're asking for turps in tiny bottles in an art shop you'd laugh your socks off!

AndyT · 24 Jun 2017

There are two common sorts of hardboard. The cheaper, ordinary grade is perfectly ok painted with oil based paints - thousands of doors were 'modernised' and painted back in the 60s.

I've never needed to try this with modern, water-based paints, but you could experiment with ordinary water-based primer as sold for interior woodwork, then a top coat of gloss or satin from the same range. In other words, treat it like softwood. For the broad surfaces you'd probably get best results with a 4" foam or fleece roller.

You could try the emulsion you have - it's probably quite similar to acrylic primer - but there is a possibility that the hardboard will absorb water from the paint and give you a rough surface. You might get away with one coat, light sanding, then a second coat of the same paint.

The better sort of hardboard, as alluded to by Ed, is "oil tempered" and is more water-resistant. If you have this, then water based paint is much less likely to spoil it. For the same size board, oil-tempered is much heavier and stronger. Naturally, it costs more, so is less common.