Hello,
I like weathing and detailing models with my airbrush but sometimes get inconsistant results. I think the reason is because when I thin it down I am not getting the proper viscosity? I think I remember seeing some kind of device that that helps you find the measure viscosity? Does anyone know anything about this and were I can find this tool?
Regards,
Frank

Check with a local auto parts store that handles automotive paint, or talk to the guys at a body shop, they use viscosity cups when preparing to paint auto body surfaces.

bhady

You need to know what you are doing, when using a viscosity cup. They come in differents sizes, for different viscosities of paint. All require a paint sample large than the quantities that you will likely be using in your air brush. Quality cups will also cost more than the average air brush.

i've never even thought of a viscosity cup. just getting into painting this is a great thread to see. i'm currently painting Nelson's paint with a hvlp gun and getting good results just approximating the viscosity. i haven't got to my airbrush yet.

You would be refering to a Zahn cup.........or a Ford cup.............or a Din cup.........among others.

In other words there are a number of different cups out there. The Zahn cup is used more in the states than the others but as was said, it isn't cheap. Last I looked at pricing for one, they are running anywhere between $15 and $130 depending on which cup....which size. There are also a number of different size cups. They come in different types/sizes depending on if you're using low, mid or high solids among other things.

If you're just doing airbrush work, you would have to mix up more than you would use just to check the viscosity since you have to fill the cup and time how long it takes for the fluid to drain from the hole in the bottom of the cup.

i just had a complete chapter of painting added to my research.[&o] i've been reading steady for an hour now on viscosity. could viscosity be measured with a stir stick for those of us mixing smaller amounts of paint?

some paints you can just stick a screwdriver into the paint a couple of inches...pull it out of paint and let it drain back in container. When it makes a tinkling sound....you got it thinned close!! your mileage may vary!

If you mix up a little of your paint, stick your mixing stick (since it's a small amount a popsicle stick works good) into the paint and pull it out. If you were trying for a solid coat, you would count the drops off the stir stick and when you get to say 9 or 10 drops before it quits, you can count it good. Since you're spraying with an airbrush, the paint needs to be a bit thinner. If you add some more reducer down to where you get 3 or 4 drips, you will probably be pretty close considering you are trying to give your model a weathered look and not an out right solid color coat.

Regardless, different colors can have a different viscosity right out of the can so once you get it close, check it out on a piece of scrap the first time to check and see if you're getting the effect you're looking for.

Good luck on your new career!

Paul

i haven't made it to my airbrush yet. still learning to use a hvlp gun. the results are coming along fine. http://www.rcuniverse.com/forum/m_6819340/tm.htm

i don't have a need for an airbrush on that project but any advance tips are always appreciated. this viscosity thread grabbed my attention in a hurry. i like the drops idea. the nelson paint i'm using comes in difference viscosities. the white is really thick, the black is much thinner. i will start experimenting with the stick and drop idea. thx.

Temperature also effects viscosity. At one point, and maybe still, the US paint industry used a standard of 77F to check viscosity. All paint was brought to that temperature before the lab tested it.

In reality, for our usage, all this technical stuff isn't necessary. Skrez is looking for a simple, reliable, way to make his paint viscosity into a reliable and repeatable form for spraying.

The best advice that I've received, is to adjust your paint to the consistency of milk. This has worked well for me.

Technically, you could easily make your own. Since you are only interested in getting the viscosity right for YOUR situation, you don't need it to match what the rest of the world is using.

Get a small container that is shaped like a test tube (one of those metal cases that some cigars come in would work)

Cut it about 1" long and glue a stick to the outside for dipping, then drill about a 5/32" hole in the rounded bottom.

Dip it in the paint, pull it out and measure the seconds it takes to reach the bottom (Don't count residual drainage)

Let's say it takes 8 seconds

If the paint it too thick, thin it out a little, measure again - maybe it's 6 seconds this time.

If the paint works well, just use 6 seconds as a target.