MDF Edges

[tsg]

Hi guys and girls, (this is my third attempt to post, cutting and pasting now !! )
this has probably been covered before but I can't find a link. I am making a cupboard and hopefully some wardrobes out of 18mm MDF. I have used it a few times before for a book case and a toy box, but I have never been able to get a smooth edge suitable for painting. Any advice??
Thanks in advance
Paul

 

[Mike.S]

Paul

I face a similar challenge in a project I'm undertaking - not just for painting but also gluing MDF edges. I don't yet have first hand experience but my understanding/plan is to smooth the edges in the usual way i.e. plane and/or sanding. The real 'trick' I believe is to then seal the edge e.g. using sanding sealer, prior to primer and top coat. MDF edges soak up paints - a bit like end grain in natural wood - so until they're sealed you're never going to get a good paint finish.

Hope that gives you some useful food for thought until someone more knowledgeable comes along.

Mike

 

[Steve Maskery]

Paul
MDF edge grain is notoriously problematic. The first step is to choose good quality MDF. Not all MDF is created equal. The water-resistant stuff (often, but not always, green) gives a better finish than the ordinary stuff.
Then use a primer specifically designed for MDF, rather than just wood.

There is a start for you.

 

[DIY Stew]

Check this out

advice-on-mdf-finishing-please-t60803.html

Alan (mailee) is the man to ask.

Stew

 

[sw_edge]

Make sure that you rip your boards with a suitable fine saw, sand edges down to 320grit and apply a coat of shellac on the edges before one more pass with the abrasive. It's always worked for me from DIY mdf to the likes of Medite, the better the quality board the less finishing you will have to do and whilst MRMDF machines pretty well it is not essential IMO.

Hope that's of some help.

 

[mailee]

Yes, as above really. A good sealing with sanding sealer is the key. I use a 2 pac primer for the edges but it is not cheap if this is a one off job. I find two coats of the sealer and then a good sanding with 320 grit does the job. I then apply two coats of finish for a smooth surface. Someone did recommend a product called Zinnser Bin but I have not tried it yet. HTH. :wink:

 

[custard]

Someone did recommend a product called Zinnser Bin but I have not tried it yet.

Zinnser Bin does the job, but it has two problems,

1. It's formulated for really tricky priming jobs like smoke stained substrates, consequently it's not cheap.
2. It's really, really hard to clean your brushes afterwards.

I've had such hit and miss results with MDF edges that increasingly I'm minimising the problem at the design stage wherever possible with lippings, mitred joins, different layouts etc. When there's no other way around it I'm in the "two or even three primer coat" camp with plenty of careful sanding.

The fact is there's no easy, cheap, quick, guaranteed solution to MDF edges, just recognise they're tricky and get yourself prepared to put the work in...if you want a first class result that is.

 

[studders]

The fact is there's no easy, cheap, quick, guaranteed solution to MDF edges, just recognise they're tricky and get yourself prepared to put the work in...if you want a first class result that is.

The only real satisfactory solution, I've found, is to apply Iron on edging to all faces that will be visible when finished.
The outlay on equipment and a bulk roll of edging is repaid with much better results that doesn't require buying special primers etc or multiple painting/sanding, time consuming, routines.

 

[tsg]

Thanks to everyone for the advice. I,ve got a number of offcuts so I will practice and try a few different ways to get the best finish. Will let you know what works best for me.

 

[tsg]

Studders, is this pre finished edging or edging that can be painted? I have so far tried a few of the suggestions with mixed results. Sill looking for that easy solution.

 

[superunknown]

I have recently completed study and bedroom furniture. Everything is made from MR.MDF. It's far superior to the standard MDF. (Mentioned in many threads on here) All my cut edges were sanded one time and then 2 primer coats applied (water based - Aquabuild)

Sanded when dry with 240 then 2 top coats. No edge issues, all came out perfect!

Sent from my Nexus 7 using Tapatalk 2

 

[rannndy]

treat the edges with a mixture of pva glue and water 20 to 30% glue. i always use ordinary mdf, no problems at all.
john

 

[Mister S]

treat the edges with a mixture of pva glue and water 20 to 30% glue. i always use ordinary mdf, no problems at all.
john

+1 for that.

Incidentally, this mixture also works as a barrier when painting over nicotine stained surfaces. When it's dry it stops anything leaching through into the new paintwork.

Steve

 

[rannndy]

good tip thanks
john

 

[Oryxdesign]

Someone did recommend a product called Zinnser Bin but I have not tried it yet.

2. It's really, really hard to clean your brushes afterwards.

Zinsser washes off your brushes very easily with bio washing powder, when I demonstrated this to a pro decorator last week he was amazed

 

[studders]

Studders, is this pre finished edging or edging that can be painted? I have so far tried a few of the suggestions with mixed results. Sill looking for that easy solution.

It can be either, and I use both types. You can get coloured plastic (Melamine?) or real wood. It's so quick to do and gives such good, professional looking results that I won't go back to other methods.

It's also a very good method for ply edges, covers any voids and makes it look almost like solid wood.

 

[johnf]

Someone did recommend a product called Zinnser Bin but I have not tried it yet.

2. It's really, really hard to clean your brushes afterwards.

Zinsser washes off your brushes very easily with bio washing powder, when I demonstrated this to a pro decorator last week he was amazed

Zinsser bulls eye does the same job but is water based so is easy to clean gear