Spray Painting MDF

[BambFurniture]

Im currently creating some furniture of which i want to gain a smooth finish, now im using child safe paint as its for a childs room.

My question is, how can i use my gravity feed spray gun to use with water based paint? How much would i need to thin it down by? Has anyone used this method in the past. Im reading alot about buying an airless one to do the job but i have the gravity fed spray gun and compressor to hand and would prefer not to spend even more money. I dont want to use a roller just down to my own preference and even using a roller i know i cant get as smooth of finish as i could with a spray gun.

BTW all my edges have been sealed already.

Any response will be greatly appreciated.

 

[RickN]

There is no hard and fast rule to thinning paint ratio's , as it differs vastly from type of paint and even down to manufacturers. first off , grab a piece of scrap material to test spray on, , start off about 20 - 25psi , and I'm assuming your using an acrylic paint, thin with appropriate thinner, ( again this can vary massively, dependent on what the base paint is ) I've used alcohol based acrylics and water based acrylics in the past. and the thin with anything from isopropyl Alcohol , Halfords Screen wash, to plain old water.

Ratio wise , take a glass or clear plastic cup, pour in some paint, get another container with some thinner in it, and add a little thinner to the paint in small amounts, mix , with a stirring stick, ( mcdonalds or starbucks are great for these ) , draw the stick against the side of the mixing container and look at the paint as it flows back down the wall of the container, your aiming for skimmed milk consistency.

I use 25ml syringe bodies to add thinner to paint, but any thing will do as long as you can control the amount of thinner you add.

Hope that sheds a little light on the subject.
Regards Rick.

 

[Droogs]

If you are intending to spray using acrylics then I would suggest that you get a Zahn #2 viscosity cup. You can get them for about £20 from fleabay. Make sure you get a #2 Though as this has the correct size nozzle/hole for paints/finishes that you are likely to use in woodworking. Each paint you buy should have a specs sheet on the manufacturers website which will state the viscosity test timings for that paint. The timing stated is for how long it takes a full zahn cup to empty, for most paints it's in the 16 - 30 seconds. that way you now you are in the right area to spray. You also need to remember that the time will vary depending on temp.

 

[DiscoStu]

My cheap Erbauer sprayer came with a viscosity cup. I would think that you could make you with just a small hole in a plastic pot. Put a fill mark on it and see how long it takes to drain. Then with some trial and error on thinning and spraying you would get a time that you know works and then you're set forever.

 

[Roughcut]

There is no hard and fast rule to thinning paint ratio's , as it differs vastly from type of paint and even down to manufacturers. first off , grab a piece of scrap material to test spray on, , start off about 20 - 25psi , and I'm assuming your using an acrylic paint, thin with appropriate thinner, ( again this can vary massively, dependent on what the base paint is ) I've used alcohol based acrylics and water based acrylics in the past. and the thin with anything from isopropyl Alcohol , Halfords Screen wash, to plain old water.

Ratio wise , take a glass or clear plastic cup, pour in some paint, get another container with some thinner in it, and add a little thinner to the paint in small amounts, mix , with a stirring stick, ( mcdonalds or starbucks are great for these ) , draw the stick against the side of the mixing container and look at the paint as it flows back down the wall of the container, your aiming for skimmed milk consistency.

I use 25ml syringe bodies to add thinner to paint, but any thing will do as long as you can control the amount of thinner you add.

Hope that sheds a little light on the subject.
Regards Rick.

Good advice.
This is the way I do it too.