I'm Trying To Get A Smooth Paint Finish, Should I Sand Down The Primer?

[fjl]

This is my first experience with trying to do an ultra smooth finish. I just painted some pieces of MDF with primer. I even used a sponge roller. One made for ultra smooth finishes. But the outcome is not what I expected. It looks really grainy. Should I sand it down? Is primer even meant to be sanded or should I just paint over the primer with the top coat and only sand that down? I'm obviously going for a smooth hi-gloss finish. What's the best method to achieving this?

[csa3d]

I feel your pain.  I tried the same thing.. including sanding down the primer.  I think the culprit in the whole matter is the roller brush.  Without spraying the paint on, it's my assumption achieving a smooth finish is next to impossible.  Maybe I'm wrong on this, but I can tell you that using Krylon (sp) spray paint made for plastic worked a lot better with the multi-coat sanding technique.  Not sure how this would turn out on an entire cab, but it worked great on my control panel.

-csa

[Hoopz]

Seriously, that search button works when you type things in it...

This is basically what  I did:

1.  Sanded MDF with 600 grit to get it as smooth as possible
2.  Applied OIL-based primer - rolled on with a 4" foam roller (2 coats).  Sanding after the 2nd coat with 220 grit.
3.  Applied water-based pink paint - rolled on with a 4" foam roller (6 coats).  Sanding after the 2nd, 4th and 5th coats with 220 grit.
4.  Sprayed on 25 coats of lacquer straight from the can - no sanding.
5.  Wetsanded like crazy with 1500 grit - I spent 8 hours just on this step
6.  Applied rubbing compound with soft cotton rag (2 coats)
7.  Applied polish with soft cotton rag and buffer (2 coats)

HERE are a few good shots of the difference the rubbing compound/polish makes.

I did not have access to any spraying tools/materials, unfortunately.  The lacquer was easy to apply though - I did it all in one weekend since each coat dried in 20 minutes.  I couldn't get it perfect but the finish still looks 1,000,000 times better than leaving brushstrokes on there with ordinary paint, IMO.  It almost looks like it came from the factory or something.

Good luck with whatever you decide to do - I'd be happy to answer any questions if I can...   

Check his links to his project too.  Then come back and tell us why it wont work for you...

[fjl]

Oil based primer? My experience with old based paints are that they very durable but takes eons to cure correctly. It takes forever to dry, smells horrible, hard to wash off, hard to spread on. It takes what, about a week so its finally sandable? 

It's too much of a hassle don't you think?

[Hoopz]

Check his links to his project too.  Then come back and tell us why it wont work for you...

  Told ya....

He uses two coats of oil based primer.  Either you can do it and get good results like his cabinets are or you can try a latex primer.  Regardless, he has a good recipe for everything else.

His paint jobs look incredible so I would advise you to listen to him. 

[sstorkel]

His paint jobs look incredible so I would advise you to listen to him.

I don't think FJL posts unless he's already decided not to listen to the replies 

[Hoopz]

His paint jobs look incredible so I would advise you to listen to him.

I don't think FJL posts unless he's already decided not to listen to the replies 

I disagree with that.  I didn't read it, but I still disagree.   

[fjl]

I don't agree to any of this.

[javeryh]

His paint jobs look incredible so I would advise you to listen to him. 

Thanks HooPZ - the reason I chose an oil-based primer was because MDF soaks up water and can warp.  The oil primer, once dried, kind of seals everything in so you can apply whatever you want on the surface.  Other people around here recommended mixing 30% Elmer's glue with 70% water and brushing it on to seal the MDF - I want to try that some day too.  The primer totally sucks to work with and I ended up throwing out all the rollers and brushes I used instead of cleaning them with turpentine.  I guess I didn't notice the drying time because I can only work on weekends like an hour or two at a time - after the primer went on it was another few weeks before I had a chance to work on it again so it didn't really matter to me.

[AcidArmitage]

dont do it! it sucks... i tried it a month ago and now im waiting for some formica laminate to come in! 

[fjl]

Don't do what? The oil based paint or the water downed wood glue?

[AcidArmitage]

paint the ultra smooth finish all together!

[fjl]

You're a very encouring guy...

Just because you failed and gave up doesnt mean I should. But I'm not gonna try to for the high plastic like side glossy finish like Javerys. I just want it to be somewhat smooth and glossy.

[JayB]

I know it's an old post but, thought I could offer some advice.

I built some studio furniture last year using MDF. My process was to seal with a PVA mix (1 part PVA to 4 part water). Do one coat and then sand with 180, then do that process two more times. That should be sealed and smooth to work with for the face. The edges draw up more so apply more heavily and maybe an extra coat and sand.

Painted with Black satin paint, sanding after each coat x 3 and job done.

Now the most important thing I found was using a particular kind of roller to get a great finish. I made the mistake of trying another on one coat and it looked terrible. The roller I use is made by a company called Hamilton, it is called Flock mini roller. It's is a sponge roller but it has a second layer that is like a very fine short hair which seems to stop any kind of pulling of the paint which can look like orange peel effect.

Trust me on the smooth finish as I ended up driving 10 miles one Sunday morning to find another they are that good.

 

[fjl]

PVA?

[nuka1195]

white/yellow glue

[coasterlvr]

I suggest using a polyester automotive primer like PCL Polyprimer.  http://www.pclautomotive.com/Product_Profile/polyprimer.pdf

I use it all the time for Car Audio stuff and paint an car like finish on top of it.  It fills, seals, and sands well and easy.  Yes, you need to sand it down in between coats and before the final paint.  You can make anything look like the paint on your car with this stuff.  Should be available at an body shop paint store near you.

[ghettodish]

my 2 cents:

Zinsser primer dries very quickly. B-I-N line of primer is schellac-based and dries in 15 minutes. It actually dries too quickly if you are rolling. It works good if you are spraying, but it is nasty stuff to be around.

Zinsser Cover Stain primer is oil-based and dries in about 45-minutes. It is good for rolling and spraying and it is sand-able. I buy it in gallons from Home Depot and I have them tint it half the color of the top-coat: Gray primer for Black paint, Pink primer for Red paint, etc. It's not good to tint the primer to the full color, it dilutes the primer too much and can cause failed finishes.

[SnApRoLl]

Kilz brand white primer works wonders for getting nice smooth finishes on all types of wood!!
I am a guitar player as well and I refinished an old Ibanez RG550 about 7 years ago and after I got the body down to bare wood and filled in any imperfections, I sanded it as smooth as possible and applied about 8 thin coats of Kilz white primer from Home Depot and once each coat was dry, I wet sanded it with 800 grit wet / dry sand paper working my way up to 1200 grit until all 8 coats were applied and I gave it a final wet sanding with 1200 grit until it was glass smooth. I took it to an automotive paint shop and they painted it in a real nice pearl red and it turned out beautiful!! Up until the neck got cracked at the head stock! 

Kilz primer is some great stuff!!! It's cheap and very easy to work with. Give it a try!


Shawn

[ChadTower]

I always use Kilz.  On projects, on the house, every time I paint.  Never fails to be the right stuff.

[galle]

sanding down the primer is ok!
I always warm up the paint! (not forget to open the can), put it on the central heater (radiator) Use no open fire!!!and then paint in thin layers.
If the result is not satisfiet? Then sanding sown the paint (only after a few days) and do the proces over again. If you want a top finish?
Ik use my car polisher.