What to use for smooth paint finish on MDF?

[justin sherriff]

I am building a corner bench breakfast nook out of MDF and need it decide on how and with what to paint it. I am looking to do a spry for a smooth finish.
Would like to try HVLP with a air compressor. I have a good compressor just need a gun for under $50 most likely harbor freight.
It looks like latex is not good with HVLP. I see some stuff about lacquer but the only lacquer paint I can find at menards is spry cans.
Any suggestions on what I could use or where I can find it?

[Chris Schoenthal]

I did a Google search for "latex with harbor freight hvlp" and came up with a thread from this forum. Basically says that a gravity feed gun doesn't work well and you need one with a pressure pot. A link is in the post to one.

Harbor Freight HVLP gun for latex paint?

[John TenEyck]

The web is your friend. Look at Target Coatings EM-6500. TC can tint it to any Benjamin Moore color. Or you can go to BM and buy Duralac WB lacquer or MegaVar WB poly/acrylic, both of which they can tint to any color. MegaVar will be the most chemically durable. All will give a hard finish. All have viscosities around 100 seconds through a #4 Ford cup. If you can get a gun with a 2.2 mm N/N you should be able to spray them w/o thinning. With a 1.8 mm N/N you will likely need to thin them at least 10%.

On MDF I recommend you consider BIN shellac based primer. It won't case cause any problems like WB primers might. The viscosity is only about 35 seconds so it will spray great through a gun even with a 1.4 mm N/N set. Also, it can be tinted towards your topcoat color to reduce the number of finish coats required.

Whatever products you choose, test everything on scrap first to make sure everything works and works together.

John

[Justin Ludwig]

You can't spray BIN through a gravity HVLP without thinning unless you remove the filter. The shellac will clog the filter in short time.

You can't shoot any WB product through a 2.2 tip gravity HVLP without thinning. You'd need pressure assist.

You're asking a lot out of a $50 HF that you'll likely hook up to a pancake compressor; especially with zero experience.

Did you know you can get a slick finish with proper paint selection, brush selection, thinning methods, proper sanding and prep?

First off - tell us what you have to work with and we can maybe steer you down a path that will achieve the results you desire.

[Bennett Ostroff]

I just went through a whole fiasco painting an MDF bookcase. I would strongly recommend brushing on a coat or two of BIN shellac based primer. Then lightly sand smooth and paint. It's the only thing that worked for me to get a smooth paint surface. I tried using several different kinds of paint right on the MDF and it sucked up the paint like crazy.

[John TenEyck]

You can't spray BIN through a gravity HVLP without thinning unless you remove the filter. The shellac will clog the filter in short time.

You can't shoot any WB product through a 2.2 tip gravity HVLP without thinning. You'd need pressure assist.

You're asking a lot out of a $50 HF that you'll likely hook up to a pancake compressor; especially with zero experience.

Did you know you can get a slick finish with proper paint selection, brush selection, thinning methods, proper sanding and prep?

First off - tell us what you have to work with and we can maybe steer you down a path that will achieve the results you desire.

Actually, you can. At about 100 seconds viscosity you can spray any of the WB products I mentioned w/o thinning, or minimal thinning, through a 2.2 mm N/N gravity feed gun. And typical WB clearcoats, which are around 45 seconds viscosity, spray w/o thinning very well through a 1.8 mm N/N set.

You do need to remove the internal filter of a gravity feed HVLP gun to spray shellac - or anything IMO - good catch.

The cheap HF guns spray surprisingly well. But I agree, most of them will need at least 6 cfm to spray well and you won't get that with a pancake compressor, but the OP said he had a "good compressor" so I took that to mean something larger.

We all learned to spray by trying.

John

[justin sherriff]

I have 7.5 cfm with my compressor setup. I will be using BIN primer.
I do have a Graco 2900 Paint Sprayer I have used to paint a few things with. But wanted to try a hvlp gravity feed spry gun.
When I decided to go with MDF I thought MDF took paint easy.

[Wayne Lomman]

Mdf does paint easily. It's one of the reasons for its existence. You have to use a primer with a bit of body to it. Edges suck up more paint than faces so the technique is to spray edges first, then the rest and then edges again. John T has the good advice on products and gear to use. Cheers

[Kevin Jenness]

I've been using Target pigmented finishes with a Qualspray lvlp gravity feed gun from Homestead Finishing. It's a bit slow because I have a relatively low air capacity (3 hp compressor), but works well with little thinning. A bigger compressor and higher volume gun it would be better. The gravity gun with 3M PPS cups is so easy to clean compared to cup guns it's ridiculous, plus the balance is better and I can spray at any angle all the way to empty.

I am using Target 5000 series primer/surfacer and 6500 pigmented lacquer with a 2.0mm tip and 9300 polycarbonate clear topcoat with a 1.3 or 1.5 tip. The finishes lay out nicely, sand easily and dry dust free quickly with low odor.

The mdf edges need to be thoroughly sanded to 220 and still take a lot of primer. To me it's a tossup whether to fill initially with glue size or epoxy or apply multiple primer coats.

John. what sort of problems do you have with waterborne primers? Have you used Target 5000?

[John TenEyck]

Kevin, I've only used SW's WB primer, "wall and wood primer" or something like that. It's really, really thick, you'd never be able to spray it with a gravity feed gun, which is one reason I prefer BIN. The SW's product worked will enough though. But I stick with BIN because it sprays great, dries very quickly, and there's no risk of swelling the wood.

An easy way to fill the grain on MDF is to use lightweight joint compound. Just smear it into the edge with your finger, then sand after it dries.

Justin, with 7.5 cfm available you should look at the Qualspray AM-6008 SmartPak with the 3M PPS cup option. It's not really cheap at about $375, but it sprays everything from WB dyes to BM Advance w/o thinning. One gun to spray everything, well, makes it a very good deal to me.

John

[Justin Ludwig]

John, maybe it's just my gravity gun. It does not like WB or latex without considerable thinning even with a 2.2 tip. I don't mind thinning material - but since I shoot mainly solvent based products I can get 2 good coats of primer or topcoat with just letting the first coat flash (I'll prep the next piece to be sprayed while the piece I just shot is flashing, then spray a second coat before I set it on the drying rack).

MDF does paint easily. Use a tack rag on the surfaces right before you shoot it. Sand any edges or machined surfaces before you apply the BIN or you'll have to apply 3 coats before the MDF stops drinking it.

Here's a full proof method to get a good edge on MDF. Coat the edge with watered down PVA glue, let dry. Hand sand to 320 or ROS sand to 180. Then start the priming process. Getting a good slick finish is all about preparation and sanding technique.

With BM ADVANCE, I wet sand in between coats because it is more forgiving and kept the sand paper from filling/gumming.

BIN sands just like a lacquer sanding sealer. STIR IT VERY WELL before spraying. I shake the can like crazy, then stir it with a wire hanger in a drill, then strain it to get the bubbles from my shaking out of it. I use a 3M PPS system that has integrated filters, so when I have about 100ml left in the cup, I have to refill and clean off the filter.

[glenn bradley]

I have 7.5 cfm with my compressor setup. I will be using BIN primer.
I do have a Graco 2900 Paint Sprayer I have used to paint a few things with. But wanted to try a hvlp gravity feed spry gun.
When I decided to go with MDF I thought MDF took paint easy.

MDF takes paint easy in the manner that it is smooth and easily prep'd. Your BIN primer will take care of the absorption issue; this is one of the reasons we prime. Let the BIN fully 'dry' and remove and nibs or irregularities before applying your color coat.

[John TenEyck]

I wonder what's up with your gun Justin. I just sprayed some GF High Performance Poly yesterday through a little 1.0 mm detail gun. It's 65 seconds in the can. I added 10% water to it, which probably brought it down to around 35 - 40 seconds, still high for a 1.0 mm N/N, but it sprayed fine.

I can spray GF's Enduro Clear Poly (50 seconds in the can) w/o thinning with my cheap 1.8 mm gravity feed HVLP gun.

I have no clue why you are having problems. As long as there are no internal filters or restrictions it shouldn't be a problem. I assume you've opened the fluid needle but still aren't getting sufficient flow, yes?

John

[Justin Ludwig]

I wonder what's up with your gun Justin. I just sprayed some GF High Performance Poly yesterday through a little 1.0 mm detail gun. It's 65 seconds in the can. I added 10% water to it, which probably brought it down to around 35 - 40 seconds, still high for a 1.0 mm N/N, but it sprayed fine.

I can spray GF's Enduro Clear Poly (50 seconds in the can) w/o thinning with my cheap 1.8 mm gravity feed HVLP gun.

I have no clue why you are having problems. As long as there are no internal filters or restrictions it shouldn't be a problem. I assume you've opened the fluid needle but still aren't getting sufficient flow, yes?

John

After every cleaning, I set my needle to max flow and my air nozzle to max pattern. I always start there and adjust down instead of adjust up. Maybe it's because my gun is designed for automotive painting (I've had it for 4 years). When I bought it, I was very very noviced. Here's how I chose it (DeVilbiss FLG4): drove to O'Reillys, asked for their selection of HVLP guns, looked through the book, and chose a $200 pretty gun. I was in a hurry! :facepalm:

You know, for the prices you talk of HF guns, it wouldn't be a loss if it didn't work out.

I'm gonna make a post about thinning material so it's not off topic here.