DIY MDF Skirting

[DontlikeDIY]

This is an attempt at homemade MDF Skirting. It's the moisture proof MDF that my husband cut himself. I've tried to prime and paint them but was left with a rough finish.

The photo shows where I have tested by sanding with sanding machine and painted one coat of satinwood.

Even though I've sanded till smooth after I apply paint I'm left with these small indents.

Can I try anything else or is this just a lost cause and should we just be buying ready made primed MDF skirting??

TIA

 

[Pat ex]

What size sanding paper are you using?
MDF is a soft wood, and needs a fine paper.

 

[oldbutnotdead]

If you are paying for the MDF, have a look at timber instead, it was cheaper last month like for like.
I've never managed a good finish when routing MDF, it always comes up a bit fluffy and porous (though the sealing stuff you paint on does help)

 

[DontlikeDIY]

What size sanding paper are you using?
MDF is a soft wood, and needs a fine paper.

It's P120 it's probably way too rough.

 

[DontlikeDIY]

If you are paying for the MDF, have a look at timber instead, it was cheaper last month like for like.
I've never managed a good finish when routing MDF, it always comes up a bit fluffy and porous (though the sealing stuff you paint on does help)

We've already bought and cut all the MDF so I have to make it work!

 

[Munroast]

It is very very difficult to get rid of that finish on MDF - it really is horrible stuff.

try oil based gloss paint, it seems quite good at filling the surface (but then you won't be able to finish with water base. Real wood is far better.

I have just had about 60m of pre painted MDF skirting delivered, I only glanced at the finish and it wasn't too bad - so there must be a technique to deal with it.

 

[DontlikeDIY]

It is very very difficult to get rid of that finish on MDF - it really is horrible stuff.

try oil based gloss paint, it seems quite good at filling the surface (but then you won't be able to finish with water base. Real wood is far better.

I have just had about 60m of pre painted MDF skirting delivered, I only glanced at the finish and it wasn't too bad - so there must be a technique to deal with it.

Thanks. I was hoping to avoid using anything oil based but may not have a choice.

I've been watching some YouTube videos trying to find a sealant of some kind. Wondering if this might work for a better finish?

I have already primed then sanded and painted over so this technique didn't seem to work for me.

 

[Deleted member 174758]

I've never managed a good finish when routing MDF, it always comes up a bit fluffy and porous (though the sealing stuff you paint on does help)

The trick, in part, is to use MR-MDF or HDF rather than ordinary MDF. Both of those machine to a better quality edge finish and absorb finishes less, so less grain raising.

 

[oldbutnotdead]

The trick, in part, is to use MR-MDF or HDF rather than ordinary MDF. Both of those machine to a better quality edge finish and absorb finishes less, so less grain raising.

I 'win' the MDF I use mainly from theatre sets so no real control over what type it is, ta for the tip

 

[Deleted member 174758]

Thanks. I was hoping to avoid using anything oil based but may not have a choice.

TBH applying any water-based finish to a timber or timber-based product will raise the grain because wood fibres always swell when you dampen them. MDF is particularly bad in that respect, hence the preference to side step the issue by using oil-based primers

What I have done in the past was to sand through the grits to something like 320 grit before (spray) finishing. The finer surface seems to absorb water less readily, although spraying as opposed to brushing or rollering also makes a difference. Even so it still requires 3 to 4 coats, denibbed between coats, to get a good quality finish

I've been watching some YouTube videos⁹ trying to find a sealant of some kind. Wondering I have already primed then sanded and painted over so this technique didn't seem to work for me.

How fine (what grit) did you sand to before priming? What type of primer dud you use? (Water or oil based? High solids?) Did you denib and prime a second time then denib and prime a third time? (For high gloss piano finishes you may need to go through this process 6 or more times - a lot of work)

Sorry, but there is no magic bullet product out there, although oil-based high solids primers get close

 

[DontlikeDIY]

We have already cut and routed out moisture resistant MDF for the entire house so thats a lot of sanding, priming, painting etc.

Is this a lost cause of a project and should we sling it all and fork out on new readymade skirting and architrave?

 

[DontlikeDIY]

TBH applying any water-based finish to a timber or timber-based product will raise the grain because wood fibres always swell when you dampen them. MDF is particularly bad in that respect, hence the preference to side step the issue by using oil-based primers

What I have done in the past was to sand through the grits to something like 320 grit before (spray) finishing. The finer surface seems to absorb water less readily, although spraying as opposed to brushing or rollering also makes a difference. Even so it still requires 3 to 4 coats, denibbed between coats, to get a good quality finish


How fine (what grit) did you sand to before priming? What type of primer dud you use? (Water or oil based? High solids?) Did you denib and prime a second time then denib and prime a third time? (For high gloss piano finishes you may need to go through this process 6 or more times - a lot of work)

Sorry, but there is no magic bullet product out there, although oil-based high solids primers get close

P21 grit sanded first then primed then water based paint. Sanded again and painted to test. All seems too time consuming!

 

[oldbutnotdead]

Was the primer water based as well? Oops. TBH I don't know why anyone would DIY MDF skirting, dado etc- the trades buy the prefinished stuff cos it saves time (cut to length, glue to wall, done) but it's the same price as real timber (or it was last month).
I'd suggest you try refinishing one section or one room (rout or sand it back to whatever profile, prime and paint with oil based paint), see what it looks like and take it from there.
If the budget will stretch, buy timber for one section, sand, prime etc and see what you think of that (or do what I've done- sand it, stain it, seal it. Wood is lovely to look at).

 

[DontlikeDIY]

Was the primer water based as well? Oops. TBH I don't know why anyone would DIY MDF skirting, dado etc- the trades buy the prefinished stuff cos it saves time (cut to length, glue to wall, done) but it's the same price as real timber (or it was last month).
I'd suggest you try refinishing one section or one room (rout or sand it back to whatever profile, prime and paint with oil based paint), see what it looks like and take it from there.
If the budget will stretch, buy timber for one section, sand, prime etc and see what you think of that (or do what I've done- sand it, stain it, seal it. Wood is lovely to look at).

Yes the primer was water based. We thought this would be money saving as we are spending a lot of money on other parts of the house. Didn't realise timber was cheaper. After watching many YouTube experiments on MDF it seems the finished look still has a mottled effect.

This is essentially the look we were going for: It's a new build house (20 yes old) so the look we are going for is modern clean edges.

 

[oldbutnotdead]

A few years ago MDF was cheaper but not any more.
Those sharp edges will make your life very difficult. Painting them without buildup on the inside corners is hard work (spraying possibly a better method), your mitres and corners have to be absolutely spot-on (any feathering will stand out instantly), the sharp top edge will highlight any impact damage, you'll get dust buildup in the channel. Entirely up to you but it feels like a showhome style- looks slick but doesn't work in the real world.