Painting MDF can be a real chore. Especially trying to paint the edge of MDF. It just drinks up the paint and takes forever to seal. It seems everyone has a different method and recommendation when it comes to painting and sealing the edges of MDF so I thought I would put 9 of those methods to the test.
Methods Tested:
The MDF test pieces were all sanded to 240 grit before applying the different methods.
For the top coats of paint I used spray gloss paint. I chose this because I thought gloss would give the best comparison surface finish between each method. Using spray paint will remove issues like brush strokes and marks left by rollers. I used Rustoleum Mode paint which is actually recommended for MDF on the can.
Method: Iron & Blowtorch
The first suggestion was one I hadn't ever considered before. I was recommended to use heat to seal the MDF before painting. This came in the form of using an iron and a blowtorch. I tried the iron method on the left side of the MDF and the blowtorch was tested on the right side of the MDF.
The iron was set to its highest heat and the steam function was turned off. I applied heat evenly across the left side of the MDF edge. It felt smoother but I sanded it and applied the heat again. This made the edge feel silky smooth.
The blowtorch was used on the right side of the MDF edge. I applied the flame until the MDF was evenly scorched. After sanding it did feel smoother but I applied the blowtorch again for a second coat of heat. After sanding the second coat it felt silky smooth.
Iron
Cost: £0.00 (only cost being electricity which I can see being fractions of a penny)
Coats: 2
Time To Apply: 2m 36s
Blowtorch
Cost: £15.20 (full 0.4kg canister of gas)
Coats: 2
Time To Apply: 24s
Results
After applying 2 top coats of paint sanding between each with 240 grit paper I was really disappointed with the finish. Before paint the surface felt as though it had sealed but the paint just soaked in and made it feel rough again.
The iron side had a flat dull appearance and still felt quite rough.
The blowtorch side felt smoother than the iron side but it was still really dull. It wasn't a great finish.
Overall I would give both these methods 0 out of 5 stars.
Edge Banding
Edge banding has been recommended by loads of people but I've never actually tried it myself.
Applying it was really easy. I cut it to length with scissors.
I could then use the iron to apply it to the edge of the MDF. It sets almost instantly.
There are specific trimming tools you can buy for edge banding but I just used a sharp knife and some sandpaper.
Cost: £8.95 (7.5m roll)
Coats: 1
Time To Apply: 3m 50s
Results
The edge banding was quick and easy to apply. Simple to trim to size and was ready for paint right away. The finish is near perfect!
It gave a silky smooth finish after both top coats of paint. It had a really high gloss appearance too.
Overall I would give this method 5 out of 5 stars.
Wood Filler
I was recommended to use wood filler to seal the edge of MDF but I was also recommended to use car body filler. Rather than buying both to test out I opted to find a middle ground and bought a 2 part wood filler instead. I hope this will offer a good compromise between the two.
Mixing the wood filler is simple. It does have a strong odour to it though so make sure you wear a mask and have plenty of ventilation. It has 10 mins of working time once mixed.
Applying it with a putty knife was simple. I can see it taking some practice to get an even coat over a large area though. It took 30 mins to dry. Once it was sanded it was silky smooth to the touch. The smoothest out of all the methods.
Cost: £1.99 per 100ml
Coats: 1
Time To Apply: 34m
Results
After applying 2 coats of paint and sanding between each the surface felt like glass. But some banding was visible. I think this is where I either sanded too much of the filler away revealing the MDF beneath or I didn't apply the wood filler as even as I thought.
It has a high gloss finish and I would say it is very close to the edge banding in quality.
Overall I would give this method 4 out of 5 stars.
Spackle or Polyfilla
Spackle was another suggestion I had. I believe in the UK we would know it as Polyfilla so that what I got. I hope it's right.
It's really simple to apply with a putty knife. Like the wood filler, I can see it taking some practice to get an even layer though. I took 1 hour to dry and even after sanding it still felt really rough.
Cost: £0.83 per 100ml
Coats: 1
Time To Apply: 1h 2m
Results
After the 2 top coats of paint the surface still felt really rough. I was surprised just how much texture the surface had.
The surface is really pitted and its given a really dull finish.
Overall I would give this method 1 out of 5 stars.
Eggshell Paint
Eggshell paint has always been my go to method for painting MDF. It's really thick which I think is ideal for sealing the edge of MDF.
Eggshell paint is easy to apply with a roller but it can also be thinned down and sprayed too. It took each coat 30 mins to dry and after sanding it felt nice and smooth.
Cost: £0.76 per 100ml
Coats: 2
Time To Apply: 1h 2m
Results
I was actually disappointed with the quality of finish on this one. It didn't have the gloss finish I'd hoped for and it was quite pitted.
The surface is semi gloss but you can see some deep pitting that reveals some of the white eggshell paint beneath. The texture on the surface is similar to orange peal too.
Overall I would give this method 2 out of 5 stars.
Acrylic Primer
Acrylic primer has been a high recommendation from a lot of people. I have used primers and undercoats before but they have always seemed watery and thin. I've never used an acrylic primer though.
Its easily applied with the roller and it can be sprayed too. Each coat took 30 mins to dry and after sanding it felt nice and smooth.
Cost: £0.60 per 100ml
Coats: 2
Time To Apply: 1h 2m
Results
The finish on the surface appeared even but did have some pitting. There was a semi gloss shine to it.
The pitting and texture is quite noticeable. Orange peel feeling like the eggshell paint but no as severe.
Overall I would give this method 3 out of 5 stars.
PVA Glue
I've heard PVA used a lot to seal MDF so putting it to the test will be interesting to see the results.
I was advised to water down the PVA glue to the consistency of milk. So I did that but I also tried to apply the PVA neat to see if there was any difference. Both methods took an age to dry. I had to apply 4 coats of each before I got it to feel relatively smooth.
Cost: £0.30 per 100ml
Coats: 4
Time To Apply: 3h 36m
Results
The resulting surfaces after the paint was applied wasn't great. Both sides, the watered down and the neat PVA looked very similar.
The texture was rough, pitted and raw feeling. It felt like the MDF wasn't sealed even after the 4 coats being applied. I didn't notice much of a difference between the watered down and neat PVA methods.
Overall I would give this method 2 out of 5 stars.
MDF Sealer
MDF sealer is a method I have tried myself in the past and I wasn't impressed by it.
Its a really thin consistency and is soaked up a lot by the MDF because of this. Very similar application to the watered down PVA. It also took an age to apply and dry. 4 coats being needed again. It did however feel smoother than the PVA glue.
Cost: £1.31 per 100ml
Coats: 4
Time To Apply: 3h 36m
Results
After the top coats of paint were applied the surface was smother to the touch than PVA glue but the finish still wasn't as glossy as I'd hoped.
The texture was still quite pitted and while it was smoother than the PVA glue, it still was textured like raw MDF. The gloss was improved with this method though.
Overall I would give this method 3 out of 5 stars.
Control - Just Paint
As a control I wanted to try just paint as both and see how it compares. I used it as the undercoating method and for the top coats.
As you can imagine its really easy to apply. Each coat took 30 mins to dry. I applied 4 coats and stopped at that point. I thought 4 under coats would make it a fair comparison with the other methods. It felt quite rough.
Cost: £1.98 per 100ml
Coats: 4
Time To Apply: 2h 40s
Results
After adding the top coats the finish was better than expected. Still not great, but better than I thought.
It felt relatively smooth although you could see areas where the MDF was showing its texture. The gloss was quite good too.
Overall I would give this method 3 out of 5 stars.
The Final Verdicts
The Cheapest Method
- Acrylic Primer -
On paper, the Iron and the PVA glue where the 2 cheapest methods. When I take into consideration the extra top coats they would require though I have to give the cheapest method to Acrylic Primer. Cheap and relatively quick to apply. It provides a good finish too.
The Quickest Method
- Edge Banding -
The blowtorch and iron where the quickest on paper but taking in to account the extra top coats you would need to apply I had to give the quickest method to edge banding. Fast to apply and gives a fantastic finish.
The Quality Method
- Edge Banding -
I gave it the highest star rating and for good reason. Edge banding gave the best finish. I would like to mention that wood filler gave a great finish too so it's a very close second but I have to give the quality finish to edge banding.
Closing Thoughts
After taking into account all the different methods I will be using 3 in particular moving forward. I'll be using edge banding and/or wood filler when the edge of MDF will be a prominent feature of a project. I'm not a fan of the costs involved but the finish quality would be worth it for important projects. I would use edge banding on flat edges and wood filler on edges that have a profile like a round over or a chamfer as edge banding would be awkward to apply to those edges.
For basic sealing of MDF edges I'll be using acrylic primer. I did hold out hope for my suggestion of eggshell paint but acrylic primer is cheaper and gives a better finish. It will be ideal for the projects that aren't as crucial. Edges that wont be easily seen or projects that don't require such a high quality finish.
But what do you think? I hope you found these tests helpful. Painting MDF is a pain but I think these tests have shed some light different options available and the costs/times involved with each.