Filling tiny 2mm nail holes in mdf skirting board before painting - polyfilla or caulk OK?

[alligatorlizard]

As title says, have some newly fitted skirting board with tiny nail holes from nailgun - about 2mm in diameter, and not very deep.

As I already have polyfilla and decorators caulk, can I just use one of these to fill these holes before painting? Of these, polyfilla would be my 1st choice as it's easier to apply out of the tube and paints over better than caulk.

I realise wood filler is what I should ideally be using, but for really tiny holes like these, does it matter? I think I should be able to just press a bit of polyfilla in, level off with filling knife, wipe surrounding area clean, and probably not even need to sand.

MDF is pre-primed, and I'll be painting over with Johnstone's Aqua Guard undercoat, then topcoat.

 

[Wayners]

Filler not caulk.

 

[Notch7]

2 pack

 

[opps]

I spent many years painting MDF cabinets that had skirtings/mouldings fitted with a 18g pin gun.

My go to filler was RedDevil OneTime. It is very soft, but the holes were too small to be hit by vacuum cleaners and so forth. 180 grit paper was enough to sand it flat

 

[alligatorlizard]

I spent many years painting MDF cabinets that had skirtings/mouldings fitted with a 18g pin gun.

My go to filler was RedDevil OneTime. It is very soft, but the holes were too small to be hit by vacuum cleaners and so forth. 180 grit paper was enough to sand it flat

Just looked up some info on RedDevil OneTime - this does look ideal - for one thing, it says it's suitable for wood, which polyfilla doesn't claim.

That said, have experimentally filled a couple of holes with polyfilla, and it looks fine so far... Holes filled, looks level, doubt you'd notice it once painted. Is there some reason why using polyfilla could cause me problems down the line though, as opposed to this RedDevil stuff (or a dedicated wood filler)?

btw, the only reason I'm persisting with the polyfilla option is because that way I could get the painting done this weekend (as opposed to having to order some RedDevil or similar) - but if there's a good reason not to use polyfilla, will reschedule - better to delay and do things properly than have to do it twice!

 

[Wayners]

The red devil is lower water content so no MDF swelling. I use a bit sometimes for filling.
2 pack is harder than MDF which becomes a problem when sanding.

 

[alligatorlizard]

I've got a feeling the nail holes are so tiny that swelling etc wouldn't be an issue - BUT have missed my slot for painting this weekend, so will take no chances, and order some RedDevil.

Unless there's an equivalent product that is stocked by Screwfix/Toolstation/Wickes/B&Q?

e.g. would "Everbuild One Strike Ready Mixed Filler" be just as good?

 

[opps]

One Strike will work. It is very similar to RedDevil, but in my experience, it doesn't sand as nicely. Not too much of an issue for tiny holes.

The powder based fillers are more likely to push out as the MDF expands and contracts- that said, pin holes, it will only expand a tiny bit. I often work in properties where I painted MDF cabinets 30+ years ago. None of the RedDevil filler in pin holes expanded.

When working with MDF, ideally any holes are as small as possible. There are times when I have to sand 2 pack filler used to fill screw holes in, for example, MDF skirting boards. I warn the customer that in a few years, the filler will become, very, very slightly proud. Bizarrely, once sanded back (again) it seems to behave. The Red devil doesn't seem to do that, but if you are filling a countersunk hole for a 5mm screw, the diameter is 8(?)mm. You will need at least two hits of the RD to get it flush (using 180-240 grit) to stop the hole becoming a crater.

 

[alligatorlizard]

Just to report back, this red devil one time filler came in very useful indeed, so many thanks for that recommendation! Not just for the nail holes in skirting, but also various general filling and smoothing of small cracks and imperfections in walls before (and during painting) - ended up going through several tubs of it!

One thing I probably couldn't have fixed without it, is when sanding plastered-over electrical chases, I was often left with some "pockmarked" areas, lots of tiny holes clustered together - not sure if that was due to air holes in the plaster/filler or due to the sanding, but anyway, was able to use the red devil to smooth all these out by just rubbing globs of it over the affected areas. Really doesn't need sanding for small repairs, you can just level it off with a knife or fingers.

I did try the everbuild one strike too, but didn't like this nearly as much - basically does the same thing, but was not as easy to work with, much more crumbly (even after adding a bit of water) and difficult to smooth off as nicely as the Red Devil.