Help wanted High Gloss finish on MDF?

[sprog1]

Hi, I want to spray some kitchen doors & I want a high gloss finish.
They are flat panels made of MDF. How do I achieve a mirror like gloss?
Can I use car paint & if so normal or 2 pack, I say car spray because I know I can get that easy enough here in Thailand
. I've looked on YouTube but can't seem to find what I want.
Thanks

[Chris Parks]

Automotive two pack will do it but the stuff is a health hazard and needs a proper booth to be sprayed in.

[malb]

High gloss doors and panels are reasonably common in Aus. They generally use a 2 pack paint on a melamine faced MDF substrate, commonly known in the trade as carcass satin. Here the material is prepared, (cut to size, hinge pockets prepared, edge sanded, and all edges/corners broken to about 1.5mm radius) at the cabinet makers, then the blanks are passed to a specialist painter to finish because of the specialist gear required and health and safety and environmental regulations make in house setups uneconomical. The painter passes the blanks through a drum sander to lightly score the face surface for a key, then coats the edges with a high build primer to fill the core surface, sands the edges smooth, and primes the face and edges with a primer suitable for the finish. The primed surfaces are then given 2 coats of 2 pack finish.

Some people do prime and spray raw MDF with car type paints and achieve reasonable results. However our standard grade MDF is never truly optically flat, so if the finish is high gloss, there are virtually always visible distortions in the finished product, similar to those that become apparent when a car body is repaired and painted without being properly filled and blocked before hand to eliminate all miniscule defects before painting. After some years operating a CNC router cutting cabinet components on an MDF vacuum spoilboard system, I can say that the surface variations for raw MDF sheets can be more than 0.5mm per face, as our skim cuts over the surface were 0.5mm deep and sometimes 3 skims per side were needed to achieve a flat surface free of patches of remnant skin, a sign of surface depressions.

Hope this helps you.

[woodPixel]

I spray MDF all the time.

Haymes TriCoat first, which is a primer, sealer, filler and undercoat. It dries fast and sands dead flat.

Next I use automotive finishes. Here we have Supercheap Auto which stocks a decent range of finishes. There is both air dry and catalysed finishes.

With reasonable precautions they are easy to spray and give a dead flat high gloss finish.

I have been playing with pre-catalysed air dry clear coats recently over colour and it's dead easy. It sprays right out of the can with no farting around (just like nitrocellulose)

One of the VERY cool aspects of this clear is it's very strong UV resistence. It can be sprayed right over ordinary timber, perfectly sealing it in a rock hard finish (which may be a bad thing)

I'm using it on veneered boxes. I'm strongly thinking of dumping urethane and nitro and using only this. It polishes to a show room finish

edit: This is the clear: Septone Paint - Acrylic, Clear, 1 Litre - Supercheap Auto Its incredibly generic. I remember spraying it way back in 1998 (when I was young and dumb) and it was the same damned can. Since I'm still alive and seem to be largely free of lung cancer, it must be not too toxic

[Fumbler]

I have been playing with pre-catalysed air dry clear coats recently over colour and it's dead easy. It sprays right out of the can with no farting around (like nitro)

One of the VERY cool aspects of this clear is it's very strong UV resistence. It can be sprayed right over ordinary timber, perfectly sealing it in a rock hard finish (which may be a bad thing)

I'm using it on veneered boxes. I'm strongly thinking of dumping urethane and nitro and using only this. It polishes to a show room finish

Woodpixel, what's the name of the clear coat you just mentioned?

[woodPixel]

Woodpixel, what's the name of the clear coat you just mentioned?

Just edited my post. It seemed a bit of an oversight to not put that in.. it was late and I was in bed on my phone

The link is posted above. The stuff is so generic it isn't funny. Plus its cheap ($20), so you can afford to just give it a blat on a test piece without having to sweat about price. Clean up is easy too. As everyone says, like everything in life, take precautions.... don't be smoking or breathing this crap in, for you will end up with a nuclear explosion or epoxy-cast lung alveoli!

I saw this stuff a week ago and thought about buying a can: ColorSpec Paint - Acrylic, Clear Coat, 1 Litre - Supercheap Auto It is twice the price ($40) but with auto sprays price really does determine quality. I've not shot any down, but I'd wager it will give a better flat, won't bloom and might lay down a little better.

Still, spraying is 90% technique. Practice on big sheets of cardboard first. If you can get your technique correct on cardboard you are 98% of the way there.

I'm only limiting my comments to address the OP with the desire to spray-get-gloss-flat-easy.....

[sprog1]

I would like to thank everyone who's replied to my thread on how to finish MDF, they were very informative. Special thanks must go to Woodpixel & Malb.
Has I've said before there are a lot of thing I can't get here Haymes Tricoat being one of them, I can get sanding sealer though
I have never thought to spray over Melamine, always thinking MDF was flat, but I now know different
I take it you rub down between each coat, what grade paper do you use? & do you use a buffing compound, like T cut to finish off?
I haven't looked yet, but is there any information on how to make a spray booth, & drying room. I have a couple of rooms I can use both measuring about 4m x 4m.
Tanks again everyone

[woodPixel]

Yeah, I didn't expect you'd get the Haymes there I was hoping that something like it might be. It really is just a general workhorse etcher-filler-undercoat that is sandable. It sands very flat.

I use 180 on a random orbital sander (Festool).

There is an outstanding video on panel preparation on YouTube. Let me find it.

Edit: here it is https://youtu.be/K0pXjV4zGDM .... This video and many others will show you that perfection in MDF is absolutely doable. Personally, I use car products as they are cheaper and the quality is outstanding. Mirka, 3M, Meguiar's and such have awesome paint finish pastes and papers.

[sprog1]

Thanks again WoodPixel, watched the video, & read quite a few comments. Doesn't it look easy when a pro does it. I think I have the idea now. so I will give it a go. I will let you know how I get on.
Has anyone got any idea's on how to make a spray booth?
Thanks

[Arron]

I haven't looked yet, but is there any information on how to make a spray booth, & drying room. I have a couple of rooms I can use both measuring about 4m x 4m.
Tanks again everyone

My view on this is don’t. There is a lot of information online about people making DIY spray booths out of tents or tarpaulins and repurposed fans. The owners normally seem pleased with their efforts but I think they are more likely fooling themselves. Without proper measurement of dust it’s easy to believe something works when it doesn’t.

Consider spraying outside. Or in a space that is generally clean but has good ventilation, and wear your respirator.

The products Woodpixel is recommending are very quick drying - by the time you’ve sprayed a panel the end where you started is dry - and the other end is dry a few minutes later. Once it’s dry, it won’t allow dust to settle - that’s the key thing. It’s slow drying products which attract every bit of dust in the atmosphere while they dry that need a spray booth. So just put it aside and go on with the next one.

As for a drying room, not necessary. Just some racks to put your panels on as you finish them.

Of course I’m talking strictly low VOC acrylic here. 2 pack is a whole other story.

[Arron]

I take it you rub down between each coat, what grade paper do you use? & do you use a buffing compound, like T cut to finish off?
Tanks again everyone

400 grit between each coat of primer, or 320. Not at all between the topcoats. If faults occur, deal with them in the buffing stage.

Afterwards, allow to harden for a few days. Then sand with 1500 grit (very lightly) and machine-buff with a quality autofinishing compound. One that doesn’t have silicon in it.

Regarding spraying mdf. The question is a bit irrelevant. If you do your priming and filling properly, then the surface will be flat and smooth. The fact that mdf is under it is irrelevant,, it’s well hidden. The topcoat only sees the Primer.

[woodPixel]

Arron is bang-on. These things are fast drying. It's a huge advantage.

I tried to address the question directly without adding additional tangents and irrelevancies.

My tiny little business has been offering spraying to my MDF-customers for about 5 years now. I've made every mistake there is to make! Some absolute disasters!

Auto products are truely incredible and offer almost consumer friendliness. They aren't your hardware store option, but if you are prepared to do a bit of work you'll get an inspiring result that you will be pleased with for years.

Àrrons point of hardening is very important. The things will flash pretty fast, but the real action takes a bit of time. From what I know (which isn't much) but there are ways to hurry it up, but it needs lamps and heat.

Once it is hard, the polishing can begin! It's very fast. Use Auto products, they are super fast at polishing with the right grit. Don't get incentive, just follow the manufacturer's method. I like 3M and Meguiar's products.

I perfected the method on my boxes (sprayed with nitro and lately polyurethane) and the results are amazing.

[woodPixel]

Ah yes! "Spray booth" are a number of refrigerator boxes I lay sideways on foldable plastic tables.

The side is cut open, so it flaps open upwards at the front.

When you've sprayed, close the front down and the bugs won't go in

I get boxes from the recycling centre. They are huge and the cardboard super thick. Fold them flat between uses so they don't take up room

[woodPixel]

A bit more here by Arron so we don't hijack (!!!) The thread: https://www.woodworkforums.com/f308/h...tricoat-221027

[sprog1]

Hi Arron, Thanks for your reply I will have to work indoors, I'm not officially allowed to work in Thailand, the police know I do a bit, but turn a blind eye has long has I don't flaunt it, so working outside is out.
Has for somewhere to dry, it's rainy season from April until about October & it's very humid, so I will have to rig some heat lamps up in another room