21 Jul How to Paint with a Paint Gun Part-2
Some tips and tricks on how to paint a smoker!
Quick shout out to SoloQue for this writeup! Thanks brother!
by SoloQue » July 18th, 2012, 1:21 pm
Thickness / Viscosity – In order to consistently spray a good coat of paint you will need to have a consistent thickness of paint. If you had access to a lab there are multiple tools out there to measure thickness but for the purpose of these guidelines we will just use a tongue blade. (pop-sicle stick)
Temperature has a big impact on paint thickness so like I said earlier aim for testing the paint under similar temps every time. If it is a little cold outside you can set the paint can in some warm water to get it around 75 – 77F. Dip the stick into the paint and see if it wants to stand up on its own. If this happens then I’m pretty sure it is too thick. If the stick wants to quickly slip to one side then the paint is on the thin side. Check the bottom of the can for settlement, if present just mix it in. (At this point you can either mechanically mix the paint until the thinner burns off or you can go ahead with the spray by intentionally backing off on the distance to the target and make a few more passes. To get a numerical idea of just how thick your paint is push the stick down until all but the top inch is immersed and pulled up quickly. As soon as the bottom of the stick clears the paint surface start counting. The count stops when you see the first real break or drip in the falling paint. The good thing about this is that you can record that number and you can have a target for future sprays. I did a few pop-sicle tests and 9 – 12 seconds (@ 77F) continuous drip time should give you a good thickness. To be honest the target here is to give you a chance to measure what you are using and be able to reproduce this thickness on future sprays. You can decide what number works best for your own spray technique.
Thinning – Anytime you are going to thin a paint with something that is not specifically listed on the paint container itself I would recommend pouring off a small amount into a cup and add a generous amount of the intended thinner. If you see strings or moss-like pieces form as you stir in the thinner or the whole thing snots up you are trying to use a non-compatible solvent which will ruin your paint. Not all pigments or resins work with all solvents so a little trial and error is advised Probably one of the most universal is Acetone but it has limits
Acetone – Try thinning in 1% by weight increments. A 5% adjustment by weight using Acetone should be easily noticed and is probably the most you would need unless your paint is extremely old and thick. Be careful using too much Acetone, it flashes so fast that the top layer of your paint can “flash” cure (like a tacky top skin) which will trap the other solvents needing to work to the surface as the paint dries. This can lead to blisters once it has cured. Acetone might not be your best bet on really hot days since it will be flashing so quickly that the paint won’t get a chance to lie down so to speak as it dries
Toluene – Another good solvent for thinning with a higher flashpoint. Toluene is a wetting solvent that will not thin as drastically as Acetone but can help with smooth lay down of the paint
Xylenes – Be careful using Xylene for thinning if you are spraying colors. Thinning with Xylene can cause colors to fall out and what you end up with could be visually off from what you thought you were spraying. The bad part is that it will not become apparent until the paint starts to dry. Especially true with yellows for some reason
Thinning with Heat – If you don’t have anything to thin with but you feel the paint is on the thick side you can put the can in some hot water and heat it up to around 90 – 95f. This will allow you to get the paint sprayed and improve the application. This is a thin and go situation since leaving a can open at elevated temps will change the properties of your paint. Keep in mind that at 95F you are probably flashing off some of the solvents and you will need to keep the 4 – 5 passes fairly quick to prevent the layers from flashing and getting tacky which will trap moisture. Note: Most paints are not made with a single solvent, they are a blend of materials that burn off at unique temperatures. To intentionally raise the paint temp will not flash off the components equally and will effect cure rates and long term performance. (lab talk there but useful to understand the effects of over heating)
Paper Cone Filters – Anytime you are using a paint gun I would recommend running the paint through a paper filter cone before actually trying to apply. You will keep your sprays more uniform and have a better chance of a good final appearance