Spray Painting MDF

[leapinlew]

I'm building a bartop and I wonder what peoples thoughts are on using spray paint on MDF?

Does it go on even? Does the finish hold? Do I need to prime it first?

[Bill Mote]

You can spray paint anything

You're not going to have the best finish using MDF, but sand, prime, sand paint, sand paint ... etc.  I used regular paint-grade plywood when I built mine.  I put 3 coats of primer on before putting 2 coats of paint.  I sanded before each coat of primer/paint.  It came out pretty nice.  Was 3 coats of primer overkill?  Probably, but it made me feel better about it.

dot

[MYX]

You can spray paint anything

You're not going to have the best finish using MDF, but sand, prime, sand paint, sand paint ... etc.  I used regular paint-grade plywood when I built mine.  I put 3 coats of primer on before putting 2 coats of paint.  I sanded before each coat of primer/paint.  It came out pretty nice.  Was 3 coats of primer overkill?  Probably, but it made me feel better about it.

dot

Hey LL
On my CP top, I played around with spraypaint. You can get a very nice smooth finish, but it was a pain in the but to get there. Dot asked if 3 coats was over kill. I had to go at least 3 coats (sanding in between) to make it glass smooth. Then I put on about 3 more layers of black (Sanding in between) for the top. Cost for cost, this is much more than getting a quart of kilz oil based primer tinted grey, sanding, recoating w kilz, then 2 or 3 layers of black (satin) sanding in between. Just get a big pack of foam rollers and chuck em after your done. No reason to use 14 gallons of solvent to save a $1.50 roller brush. 

[sealslayer]

I sprayed the whole inside of my cab after having major disasters painting it with a roller, I just couldn't  get the same sort of smooth finish with a roller than with a spray gun.

It took 6 coats to spray mine but that was mainly because I should have used white primer not grey.
Getting a super smooth finish is easy even if you can't spray too well, just let it dry for a couple of weeks then fine sand with 1200+ grade sand paper then using fine rubbing compound to get the super glossy shine.

[javeryh]

I will be needing some MDF painting tips soon too.  I'd like a high gloss finish if possible but the only spraying I can do is out of a can - I don't have a sprayer or anything...  What type of rubbing compound do you use?  How long does it last?

[sealslayer]

You can still achieve a perfect finish with spray cans but your going to need a lot of them, so many so that it may be worth your while hiring a compressor and spray gun for the weekend.
You may also encounter problems with overspray using cans because your not going to be able to spray a large area quick enough unless you have a couple of helpers shaking the next couple of cans ready for you to use, you can buy triggers that clip onto the top of the cans to make life easier on your thumb.
Car spray paint is touch dry pretty quick so you may be better off spraying one section and masking the other areas off to avoid overspray then let the panel you've sprayed dry then cover that one and continue with the others etc...

I used two different grades of farleca compound, I'm not sure what country's its available in but a good car spray paint shop will sell rubbing compound, make sure its a shop dedicated to car paint and not a general car spares shop as they will only sell regular cutting compound that ends up taking too much paint off.

Start with ultra fine wet n dry paper 1200 grade or higher with warm soapy water, washing up liquid is best. first to get rid of any orange peel effect, only lightly sanding otherwise you'll take too much paint off.
when you have it nice and smooth and it all looks a uniform matt texture with no shiny pits in it use the first regular grade of compound on soft cloth wet cloth in circular motions until the shine starts to appear, wipe that off then use the ultra fine finishing compound for the last stage, then use a nice car wax to get the gleam 

Make sure you have left the paint to dry long enough, two weeks is best unless you can leave the cabinet in a room with the heating on for a week so it gets time to bake nice and hard.

[Fozzy The Bear]

I'm building a bartop and I wonder what peoples thoughts are on using spray paint on MDF?

Does it go on even? Does the finish hold? Do I need to prime it first?

Spray painting MDF is really easy..... I know exactly why people have problems with it, and the cure is so simple that it seems to have been missed here.

The problem with MDF is that it soaks up paint like a sponge and dries rough as hell! Unless you follow this little tip:

1) Sand thouroughly with 400 Grit wet and dry paper, used DRY!! very important don't get the MDF wet YET!!

2) Get some weatherproof PVA (White Glue) and thin it down approx 30% PVA to 70% water... maybe even a little thiner than that.

3) Paint it on with a brush! letting it soak well into the the MDF.  Give it pleanty of time to dry out.

4) Your MDF is now sealed and you can sand the surface with 600 Grit Wet and Dry Paper (again used dry)

5) Spray paint the surface with any finishing paint you like ( I like Plasticote "Rust Not" Matt Black, for black finishes... It comes kind of satin finish on this surface) The finish will look almost exactly like it's been laminated.

No need for primers and huge numbers of rubbing down layers and all of that stuff!! Just whak the top coat on. It holds really well on top of the PVA sealer and looks great!!

Best Regards,
Julian (Fozzy The Bear) 

[AlanS17]

I just started pealing the sideart from my TMNT cabinet, and it looks sealed underneath. Would this be safe to paint on? I'm assuming so. Could I get away with using a roller or do i still need to spray?

[johnvv]

The problem with MDF is that it soaks up paint like a sponge and dries rough as hell! Unless you follow this little tip:

1) Sand thouroughly with 400 Grit wet and dry paper, used DRY!! very important don't get the MDF wet YET!!

I'll disagree with Fozzy, though his method may well work.

- If you are going to sand MDF, you must use a mask and work in a well ventilated area.  The MDF dust is, esentially, toxic.  Check prior threads on this.

- The point of priming MDF is to a) protect it from water and moister which will severely damage MDF and b) give it a smoother surface for the paint.  There a lots of threads on this as well.

So, it is not really much effort to spray (with a can) or apply (with a roller) one or two coats of primer.  You just need to lightly sand, by hand, between coats.  Wont' take more than about 5 minutes per side to sand.  If you use an oil-based paint then you must use an oil-based primer.  for latex paint, use a water-based primer.

As noted earlier, regardless of which method you use, let the paint cure for 10-14 days before doing any further work on it (polishing, side art, etc).

[Fozzy The Bear]

The point of priming MDF is to a) protect it from water and moister which will severely damage MDF and b) give it a smoother surface for the paint.

Sorry?? You're not disagreeing with me at all.... That's exactly what I said.

However: The method I gave there takes 1/10th of the time because you don't have to wait days for two primer coats to dry with sanding in between and it takes the topcoat straight onto the sealed surface with near perfect results.  I've never had it fail on me yet. On top of that you can paint it with water based or oil based paints with no adverse reaction.

The PVA soaked into the MDF seals and protects it totally, preventing moisture penetration of any sort. In fact so much so that I've seen and been in a boat built this way.

Try it out for yourself! It works, it's faster, it's cheaper and it requires 10 times less effort to get a great result.

As for letting the paint cure for 10-14 days before doing any further work on it (polishing, side art, etc)..... If you follow the above method and use the paint that I suggested you can do all of that after 10 hours! after that amount of time it's rock hard set and more or less cured.


Best Regards,
Julian (Fozzy The Bear)

[Mamed for life]

So, it is not really much effort to spray (with a can) or apply (with a roller) one or two coats of primer.  You just need to lightly sand, by hand, between coats.  Wont' take more than about 5 minutes per side to sand.  If you use an oil-based paint then you must use an oil-based primer.  for latex paint, use a water-based primer.

As noted earlier, regardless of which method you use, let the paint cure for 10-14 days before doing any further work on it (polishing, side art, etc).

Hi Fozzy,

Would this be a good options for rolling on paint, then? A 250ml tin of MDF primer in B+Q near me is nearly €20! Would this be a good option instead of primimg: seal it like this then use a roller to paint on the semi gloss paint?

[AlanS17]

Regardless of what you're painting onto, priming is always good idea. Some people just consider it a nicety while other consider it a necesity. Priming doesn't just give you a smooth finish, It can affect the durability of the paint job. It all comes down to a matter of personal preference.

If you're spending $550+ on a cab, spending $20 on primer for the "skin" isn't such a bad idea. After all, it's the part of the machine that everyone see no matter what side they're standing on.

[javeryh]

So using either primer or Fozzy's glue mixture accomplishes the same thing (which is sealing the MDF and readying it to accept paint)?

I am inclined to give both methods a shot on some scrap MDF over the next few days and see which finish I like the best and then apply that to the entire cabinet.  I'm really hoping to get results similar to what sealslayer got.  That's a really nice finish!

Fozzy - is the PVA really just regular old white glue (like Elmer's)?

THANKS!!

[Mamed for life]

Regardless of what you're painting onto, priming is always good idea. Some people just consider it a nicety while other consider it a necesity. Priming doesn't just give you a smooth finish, It can affect the durability of the paint job. It all comes down to a matter of personal preference.

If you're spending $550+ on a cab, spending $20 on primer for the "skin" isn't such a bad idea. After all, it's the part of the machine that everyone see no matter what side they're standing on.

No disagreement from me: I haven't built yet but like I said, only 250ml is 20 bucks. I'd need, what, about 8 tins, to roll a full size cab? It's the only size available, so if Fozzy's method would work for rolling on MDF, I think it would be good. Mind you, I reckon I'll have a test run on a piece of scrap first, as well!

[AlanS17]

What are you buying that costs $80 per liter??? That $20 ought to buy you enough primer to do a couple of cabinets.

[Fozzy The Bear]

Fozzy - is the PVA really just regular old white glue (like Elmer's)?

Sorry I have no idea what Elmers is... I live in the UK and we don't have that brand over here.

What you need to look for is sold as weatherproof or Exterior Use(waterproof once dried) PVA Glue. It is a white glue, so maybe the Elmers brand you're talking about would do the job. The brand I use over here is EVO-STICK Weatherproof Wood Adhesive (sold by B&Q and no doubt by other retailers as well)

In reply to "Mamed For Life" Yes it's fine to roller onto it afterwards. But do make sure you follow the sanding instructions for the best results, and try one of those smooth foam glossing rollers.

Best Regards,
Julian (Fozzy The Bear)

[Mamed for life]

What are you buying that costs $80 per liter??? That $20 ought to buy you enough primer to do a couple of cabinets.

Hi AlanS

Yeah, that my point: when I went to B+Q (UK retailer) I asked for primer for MDF and was told that that was the only one they had. Looking back now, I must have my numbers wrong; but it was only the small tins, you know (1 litre)? From what i've seen on the boards, I was going to prime at least 2 or 3 times, and one of those little tins looks like you wouldn't even get one coat on a cab out of it! At least, not the way I splash paint around.

Thanks for the tip Fozzy, I'm going to try your recommendation!

[sealslayer]

If your spraying then your better off using a primer that's the same chemical as the gloss topcoat, i.e acrylic, 2pack,cellulose etc..
Primer in spray cans seals the MDF perfectly well especially if its filler primer or high build primer.
Remember your top coat of gloss is only going to be as smooth as your primered base coats.
Rolling primer on then spraying on top will look awful unless you sand it down to nothing, if that's the case then you may as well spray the primer from the start to get the smoothness rather than rolling or painting with a brush.
For quality of finish you can't beat spraying especially if your cab is already built, trying to use a roller on joined edges without leaving any roller or brush strokes is very awkward and time consuming and a major pain in the ass.

Personally I would never hand paint again, I'd either spray, or for the perfect result with less mess and time wasted I'd laminate it.

[javeryh]

I'm going to give the spray painting a try on some scrap MDF.  I had problems on my last cab getting into the corners/joints and making everything look smooth (there are a few small runs).  I will be butying the paint in cans though because I don't have a sprayer or anything.  In order to get a smooth, mirror-like finish I guess I'll pick up:

1.  white primer/waterproof glue (I'm going to try both methods)
2.  colored paint
3.  sandpaper
4.  rubbing compound

Is there anything I'm forgetting?  How many coats of each should I put on there?

[ahofle]

Just curious why so many people are after glossy/mirror finishes on their arcade cabs.  I don't recall ever seeing an actual cab that was glossy.

[javeryh]

Just curious why so many people are after glossy/mirror finishes on their arcade cabs.  I don't recall ever seeing an actual cab that was glossy.

I can't speak for the others but I'm building this cab for my daughter and I want it to be as girly and fancy as possible.  It's tiny (80%) and I think a mirrored, glossy finish will go with the girly pink theme.  I probably wouldn't finish a "real" cabinet like this though but that's just me.

[AlanS17]

I personally don't need a mirror finish. I would settle for uniform. I intend to get some adhesive-backed sideart onto my next project anyways. It might be the last machine I ever build, and I want it to be a good one.

[ahofle]

Just curious why so many people are after glossy/mirror finishes on their arcade cabs.  I don't recall ever seeing an actual cab that was glossy.

I can't speak for the others but I'm building this cab for my daughter and I want it to be as girly and fancy as possible.  It's tiny (80%) and I think a mirrored, glossy finish will go with the girly pink theme.

Wow, that is awesome.  Your daughter is a lucky girl.

[sealslayer]

I'm going to give the spray painting a try on some scrap MDF.  I had problems on my last cab getting into the corners/joints and making everything look smooth (there are a few small runs).  I will be buying the paint in cans though because I don't have a sprayer or anything.  In order to get a smooth, mirror-like finish I guess I'll pick up:

1.  white primer/waterproof glue (I'm going to try both methods)
2.  colored paint
3.  sandpaper
4.  rubbing compound

Is there anything I'm forgetting?  How many coats of each should I put on there?

If all your holes are filled nicely then that's all you should need, when it comes to spraying the primer I'd go with 3 coats sanding between them all.
My cab took 6 coats of paint but as I said earlier I could have got away with less if I had used white primer.

As your going to be cutting back with the compound I would spray until it looks nice and even then add one more coat for the paint that will be lost while you are lightsanding and cutting back with the compound.
Its very easy to sand too much and suddenly see the primer appear underneath and make all your hard work a waste of time.

Here's a link that a member placed on another topic about spraying, it shows all the principles of using compound etc.

http://www.mnpctech.com/case-mod-paint-computer-pc-case-mod-how-to1.html

If you do end up getting a run then let it dry for about 20 minutes and sand it back with medium grade wet n dry until its smooth then continue spraying, its no good spraying over it as it will get higher and higher the more coats you put on.

Only other advice I can offer is go slow and steady, practise on some scrap, go too slow and you'll get runs, go too fast and you'll get a uneven spray pattern.
While your spraying your looking for a nice gloss appearing as you spray if its not then your going too fast.
Start at the top of the panel and move left to right then come across the panel about a  inch lower so the new line of spray half covers the line you just sprayed  from right to left and continue until you get to the bottom, don't be tempted to go back and cover a bit if it looks blotchy, you can cover that bit on the next coat.

Your probably going to end up with overspray but don't worry about that you can light sand that down after its dried nice and hard. If it looks and feels rough after you have finished don't worry that wont be your final finish, once you get your hands on the compound you'll truly see your hard work come to light.

[javeryh]

Thanks for the tips sealslayer. 

Can you buy spray paint in any color you want or are you limited to what is in the cans on the shelf? 

[sealslayer]

Here's where it starts to cost money, if you go to a regular car spares shop they may have 50 or so cans on display for regular cars like ford etc, you may have about 3 or 4 different shades of each colour but that's about it.
If you go to a dedicated car bodyshop supplier they will have colour charts for almost any shade of colour you want.
Over here a regular can of spray paint will cost 4-5 Pounds ($10) for 500ml, to get one made up for your exact colour it costs 12.99 ($25) that works out to be very, very expensive, I don't know it may be cheaper for you.

I worked out I would need at least 20 cans to do my cab so it was cheaper for me to buy a compressor and spray gun and buy the paint in litres that I could dilute with thinners at a 50:50 ratio, it cost me 25 pounds for 1 litre that I thinned down to two litres.
It still worked out at over 100 pound ($200) in paint but I saved in the long run and have a compressor for any jobs in the future.
I took a section of T-Molding with me to the body shop suppliers and they made the paint up to the exact colour, when you look at the cab you can't seen any difference at all in the two.
If you can get the paint cheap enough then great, but do consider getting a compressor if you can, the finish will be much better giving you Less work at the end and you'll always have it for other jobs should the need arise.

[javeryh]

I'm going to go for it this weekend!  I'm just going to test finish a scrap panel and see how it comes out.  I've got to buy a spray gun.  Will this do the job?  http://tinyurl.com/yn5q6b

Or can someone recommend a somewhat inexpensive spray gun to use?  Do I just pour any old paint into the container or so I need special paint made to be sprayed on?

Now I'm thinking I should figure out a way to paint and finish everything prior to assembly but that might be more trouble than it's worth...

[Xam]

I'm going to go for it this weekend!  I'm just going to test finish a scrap panel and see how it comes out.  I've got to buy a spray gun.  Will this do the job?  http://tinyurl.com/yn5q6b

Or can someone recommend a somewhat inexpensive spray gun to use?  Do I just pour any old paint into the container or so I need special paint made to be sprayed on?

Now I'm thinking I should figure out a way to paint and finish everything prior to assembly but that might be more trouble than it's worth...

Harbor Freight has a paint sprayer that they frequently put on sale for $12.50. I purchased one some time ago, but have yet to use it. I cannot say if it works well or not. I should know soon as I am getting ready to paint this weekend (if the weekend goes well).

Xam

[sealslayer]

I can't see what that link goes to, it showed laptops lol, I believe you can buy electric sprayguns but I'm not sure how much pressure one of those gives out.
I used a small 2hp compressor and a spray gun that was designed for spraying car paint.

You can probably use any paint as log as the viscosity(sp?)  is correct, to thick and it wont spray, too thin and it'll run.
I'm sure you could use regular paint and thin it down as needed, although I've only ever used compound and fine wet n dry on paint that it was designed for, I have no idea if its even possible to compound domestic house paint or paint that's regularly used for cabs.

[MartyNg]

Fozzy - is the PVA really just regular old white glue (like Elmer's)?

Sorry I have no idea what Elmers is... I live in the UK and we don't have that brand over here

Did anyone figure out what an equivalent to to "PVA" is in the states yet?

[Fozzy The Bear]

Fozzy - is the PVA really just regular old white glue (like Elmer's)?

Sorry I have no idea what Elmers is... I live in the UK and we don't have that brand over here

Did anyone figure out what an equivalent to to "PVA" is in the states yet?

Yes.... Read the thread a little closer... You are looking for "PVA Based Weatherproof White Wood Glue" Your local DIY store will be able to supply this for you.

Best Regards,
Julian (Fozzy The Bear)

[MartyNg]

Yes.... Read the thread a little closer... You are looking for "PVA Based Weatherproof White Wood Glue" Your local DIY store will be able to supply this for you.

Best Regards,
Julian (Fozzy The Bear)

Yeah, I was hoping someone had a brand name so I don't have to waste time and money finding the one that's as close to yours in the UK as possible.

[javeryh]

OK, I had a slight delay in getting to the priming and painting of my MDF cab but tonight I am going to Home Depot straight from work and buying the necessary supplies to test out on scrap.  Any thoughts on painting in semi-cold weather.  I'm in NJ and it's been pretty mild but I'm afraid it's not going to last much longer.  I'll be painting in an unheated garage so no wind. 

Anyway, I hope this works!

[MartyNg]

OK, I had a slight delay in getting to the priming and painting of my MDF cab but tonight I am going to Home Depot straight from work and buying the necessary supplies to test out on scrap.  Any thoughts on painting in semi-cold weather.  I'm in NJ and it's been pretty mild but I'm afraid it's not going to last much longer.  I'll be painting in an unheated garage so no wind. 

Anyway, I hope this works!

I'm in NY and I found that spray painting under 50 degrees does not seem to work well if it is left in the cold. I left it in the garage just overnight after painting, and then brought it in the house the next day. DAYS later, the paint was still coming tacky!

[javeryh]

I couldn't find the PVA Glue at Home Depot - they had no idea what I was talking about but they are kind of moronish there...  anyway, I bought a sprayer and I'll be applying the primer today (although I'm going to brush the primer on and sand in between coats.  I anticipate 2 coats of primer followed by multiple coats of pink Behr paint (basically however many it takes until it looks right) sanding in between each one and then applying a top coat of rubbing compound which I'll buff out.  I wanted to get this done a while ago but real life keeps getting in the way of things!

Here's what I'm going to do (on some scrap MDF):
1.  Brush on 2 coats of primer and sand in between coats
2.  Spray on a bunch of thin coats of pink paint (sanding in between)
3.  Apply rubbing compound and buff it off with a cotton cloth

Whew!  I hope this goes well - I am excited to try though...

[fjl]

You shouldn't even call it PVA glue. I saw some at home Depot the other day. It should be where you get wood trimming. It'll say its for cabinets and or furniture and say that its weatherproof. Usually comes in brown or light brown color. And Elmer's Brand does make some of this glue.

[Ed_McCarron]

Plain old Elmer's Glue All seems to be a PVA (poly vinyl acetate) glue.  Snippet from the MSDS:

1. Chemical Product and Company Identification

 

     DESCRIPTION:     ELMER'S GLUE-ALL

     PRODUCT TYPE:    PVAC BASED ADHESIVE

Or am I missing something obvious?

[fjl]

Elmer's plain old white glue is usually used in schools for paper crafts and projects. It's not weather proof and it s not very strong. Yout don't want to use it as a permament or even a temp hold.

The better type to use the one that comes with wood fibers for sanding down and is weather proof. Elmers makes such glue. But then so do many other companies. Don't have to go with Elmers.

[Fozzy The Bear]

The better type to use the one that comes with wood fibers for sanding down and is weather proof.

In this application you most certainly DO NOT want one with wood fibres in it. You want plain ordinary "weatherproof white PVA wood glue" It's not for glueing things it's for sealing the surface so that it takes paint!!!

Best Regards,
Julian (Fozzy The Bear)

[RayB]

I skipped the entire thread. In answer to the main question: LOTS OF LIGHT COATS. Too much and it runs and gets all bump. Light sanding between coats too.