Edges of MDF prior to paint, filler, edge banding or lots of sanding?

[Designer1]

So, been testing a new way of making shaker doors today, basically running a router with a 6MM straight flute cutting bit 60MM away from the edge of the door using a fence to cut out the centre, rebating the back with a cutter at a depth of 9MM for a panel and pushing it in with a small amount of glue. Going to be doing a few with different styles pretty much to go on the website so customers can see the styles we do (window shopping often turns to real shopping lol).

In the past I've used filler but got a bit fed up of putting filler on every edge trying not to miss any so there's no chips or anything and I sometimes question its durability over time (made a blanket box last year from 18MM MDF and put some 9MM panels on the outside, just something for home didn`t have to be too fancy, the top where the lid rests has some chips from things in the box and presumably the lid itself).

Then for future projects moved onto a quick coat of filler primer on edges and sanding between coats of Leyland acrylic primer before top coat (120, 240, 320), this has been working well and had minimal problems to date.

Never used edge banding will probably try that next. Heard good things about poplar strips glued and pinned onto edges too, probably try this at some point as well, can get a bit finnicky if putting an ogee on or something, will have to make sure poplar is thick enough to take the profile.

What do other people like to use? Or if there's any other method feel free to input.

Designer1

 

[Doug71]

What kind of MDF are you using? As long as you use the moisture resistant stuff the edges don't normally cause too many problems.

 

[doctor Bob]

Are you doing this by hand or cnc, this seems a very complicated way of making a shaker door.
Like doug I just spray edges.

 

[baldkev]

As above, the mdf query.
Theres also different grades of moisture resistant. The caberwood standard mr is wooly when cut. The caberwood mr pro is a lot denser, like medite mr, but i would say the medite is smoother on the face to begin with.

One thing that might not help is using acrylic. The first coat will help bind the fibres to be sanded back smooth, but then you need to use oilbased. I prefer oil based for the first coat too if i want it to be a good finished edge. The water contenkt in acrylic can raise fibers the same as with wood ( less so with m.r )

 

[petermillard]

As above, use decent quality MR MDF (Medite, Finsa) and you don’t need to do anything special with the edges. And as Bob says, unless you’re doing this on a CNC that seems a very convoluted way to go about making a door.

 

[Designer1]

Awesome thanks for the replies, much appreciated.

 

[Droogs]

This topic has been brought up a few times. My method of treating the edge of all types of MDF especially profiles is to create the profiled edge but to deliberately make it fractionally 1/2 a mm too deep. Then I splodge on a layer of Isopon/Bondo car body filler that has an extra squirt of hardener in the mix. Once this is set (24 hours) properly I then run the edges again to get the right dimensions and profile. This gives me a fantastic surface to the edge, which is ready for painting with crisp clean features. Here is an example of the finish you can get (these are the drawer fronts for my router table in L/R metallic forest green)