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Urethane paint, need the basics.


sak

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I think I will give urethane paint a try, but I need to know the basics. For example, what to thin it with, is it happy over testors enamels or dupli-color or tamiya based paints.

Thanks

Jeff

Jeff urethane can be shot over any paint as long as it is dry. However you MUST WEAR a carbon filtered facemask!!!

:D

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Jeff urethane can be shot over any paint as long as it is dry. However you MUST WEAR a carbon filtered facemask!!!

:D

Jeff,

Len is correct. When you start getting into the urethanes, you start getting into some really nasty solvents that will eventually kill you if you don't take the necessary precautions. Of course anything can kill you, but you can be proactive to prevent this one from doing so.

The model paints are docile compared to the urethanes (I am referring to the automotive kind).

The big thing to remember with urethanes is this: to avoid compatibility issues, it is best to stick with the hardner, reducer and clear made by the same company. Mixing a PPG hardner with a DuPont clear will cause all kinds of problems either up front, or down the road. While they are docile when sprayed over all bases (color coats), they perform best when mixed with like chemicals that the chemist designed them to be mixed.

You will find the urethanes are more expensive than model paints, but you get a more because most paint jobbers don't mix bases or sell clears in less than a quart. You will need to buy the clear, the hardner and the reducer. I use PPG and the Concept 2021 is AWESOME. I have areas that don't need to be buffed when I spray it. It is suppose to be a 4:1:1 mix meaning 4 parts clear, 1 part hardner, 1 part reducer. I generally mix about 2-3 parts reducer to get it to flow better. It won't matter on a model if you over reduce it. What ever product you use, ask for the mix sheet and the MSDS sheet so you know how to mix it and how to spray it. I have sheets on all my products because each one is different and I can't remember. I have a paint folder with the sheets and when I am spraying a particular product, I grab the sheet and it tells me mix ratio, PSI, Flash times, recoat times, pot life and all. It's nice to have this on hand.

Go to Home Depot and get you a mask that has changeable filters (canisters) and buy a few extra canisters while you are there. Trust me. I bought only the mask, and when I went to get new cans, they said "oh, we don't sell that kind of mask anymore" so I had to fork out anther $30 for a new mask.....and this time I bought a few extra cans.

And your lungs are worth $30. Trust me.

David

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Just a little tip from someone who has to wear a respirator for work. IF you have a beard or heavy mustache your respirator can be ineffective. You need a tight seal around your face. To test fit cover the both filters with your hands (like in the pic) and breath in. It should suck to your face a little bit. Now you know you have a good seal. Put your hand on the middle vent and breath out a little it should puff out a bit. Now you know the exhalation valve is working. Inspect the flaps on the inside and make sure they are not cracked. Check the gaskets on the filters. When you are done using it take a Alcohol wipe and clean it.

The most important thing to do with your respirator is when not using it Seal it in an airtight bag. Once you open the filters they never stop working. If you leave it hang on the work bench the filters are absorbing anything that is opened or sprayed. Glue has fumes an open container of thinner has fumes or that quick spray job you just did. Those filters are working even though you are not pulling air through it. Check to make sure you have the right filters some will work for certain applications some will not .

Read the label on the filter.

Last but not least if you stick a respirator on your face and you have a hard time breathing because of a medical condition take it off right away. Breathing through a respirator makes your body work harder you could get into trouble really quick. The minute you feel light headed or have any trouble breathing take it off. If you are claustrophobic

you may have a hard time wearing one it sounds silly but I have seen people in a panic when they have to put one on. What ever material you use make sure you have the right filters.

post-4026-12822722508591_thumb.jpg

Edited by mredzadventure
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This is great info because shooting urethane coats sims like such a mystery. I bought a quart of Concept DCU2021,DCX61 hardener & the reducer DT885. I plan on trying it soon. How long of a window once mixed is there before it gels? Should I mix just enough to make one coat wait ten minutes or so (not sure)then mix up another or will it last a few hours?

Edited by slapshot
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This is great info because shooting urethane coats sims like such a mystery. I bought a quart of Concept DCU2021,DCX61 hardener & the reducer DT885. I plan on trying it soon. How long of a window once mixed is there before it gels? Should I mix just enough to make one coat wait ten minutes or so (not sure)then mix up another or will it last a few hours?

Read your MFGR supplied info sheets.....they tell it all , ratios, temp, pot life, safety tips for proper use.

Any place that sells these products should have all the sheets including MSD...they also will tell you what works if you ask.

Also urethane colors do not need hardener, the clears do. You can also shoot clear lacquer over a urethane base

Edited by MikeMc
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This is great info because shooting urethane coats sims like such a mystery. I bought a quart of Concept DCU2021,DCX61 hardener & the reducer DT885. I plan on trying it soon. How long of a window once mixed is there before it gels? Should I mix just enough to make one coat wait ten minutes or so (not sure)then mix up another or will it last a few hours?

Gary,

You need to get the info sheets for the products you are using so you know all the important stuff like mix ratios, pot life, PSI's and a lot of other GREAT info that changes for every product, so it's hard to remember everything unless you use this stuff everyday.

The pot life for 2021 is about 4-6 hours. You should only mix what you need as it will harden and serves very little purpose other than being a lake on a diorama.

David

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I can only give take on Dupont Hot Hues... With the paint I use the mid reducer this gives me up to 30 min window plus at 73 degrees in a air controal room this works good. Plus I heat up the inside of my spray booth to a 140 degrees with a little floor heater.. I put the heater in side it and cover the openning with a cardboard sheet. This will help the paint cure good and also lay down the best.. I shoot the paint nothing over 10 psi at the tip. ( No thinning needed with this paint as its real thin as it is.) Clear coat I still do the same above and shoot it at 7psi at the tip and still no thinning.. I can not speek for the PPG stuff but the window for doing 2nd coats on this I take the high road and wait the 3 days before putting on the clear coat after shooting the color. You can touch it once the clear is on after 6hrs but would recomend waiting the 24hrs before wet sanding and buffing.. You do not want to wait longer as then it will be too hard to wet sand.

Hope this helps on some things.

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Road, Du Pont does recommend to achive the best color resualts using the Hot Hues line a 72 hr wait.. This paint and also some of the Chromsystem paint line with the hues in the paints they do change (Sade) color from the time you spray it till the time they fully dry out.. To do it with out waiting the 72 hrs is if you bake it on like a normal body shop would. I have some red paint right now that you can watch it change shade colors every hr and and if you clear to soon you will get that shad of red and not what the full color is suppost to be.

Edited by Chas SCR
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Just a little tip from someone who has to wear a respirator for work. IF you have a beard or heavy mustache your respirator can be ineffective. You need a tight seal around your face. To test fit cover the both filters with your hands (like in the pic) and breath in. It should suck to your face a little bit. Now you know you have a good seal. Put your hand on the middle vent and breath out a little it should puff out a bit. Now you know the exhalation valve is working. Inspect the flaps on the inside and make sure they are not cracked. Check the gaskets on the filters. When you are done using it take a Alcohol wipe and clean it.

The most important thing to do with your respirator is when not using it Seal it in an airtight bag. Once you open the filters they never stop working. If you leave it hang on the work bench the filters are absorbing anything that is opened or sprayed. Glue has fumes an open container of thinner has fumes or that quick spray job you just did. Those filters are working even though you are not pulling air through it. Check to make sure you have the right filters some will work for certain applications some will not .

Read the label on the filter.

Last but not least if you stick a respirator on your face and you have a hard time breathing because of a medical condition take it off right away. Breathing through a respirator makes your body work harder you could get into trouble really quick. The minute you feel light headed or have any trouble breathing take it off. If you are claustrophobic

you may have a hard time wearing one it sounds silly but I have seen people in a panic when they have to put one on. What ever material you use make sure you have the right filters.

Good advice on the respirator use Ed as I had worked at a nuclear power plant and guys with beards were required to shave them off in order to wear the respirator correctly like you stated.

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Some air compressor's do not put out what they are saying if you have a meter with a water trap at the compressor and line.. I have to one at the start of the line and one connected to the air brush and line.. On the compressor I have it verys between 1 to 2 lbs.

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I shoot the paint nothing over 10 psi at the tip. ( No thinning needed with this paint as its real thin as it is.) Clear coat I still do the same above and shoot it at 7psi at the tip and still no thinning..

I have to one at the start of the line and one connected to the air brush and line.. On the compressor I have it verys between 1 to 2 lbs.

I've always done it pretty much the same as Len, shooting at 30-35 lbs, except for Alclad, which is 10 or so. I'm somewhat intrigued/puzzled by your method, Chas, but maybe I'm not following it correctly. You say you have 1-2 lbs at the compressor and 7-10 lbs at the "tip"? How is that possible? Mine drops a few lbs through the line, not gains....not much, but it does drop a little. If I only had 1-2 lbs at the compressor, it wouldn't spray anything at all. :blink:

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I'm sure that my set up is pretty close to the gauge reading. I shoot mostly with a Paasche H @ 32-35 .lbs. I have noticed that when I activate the the trigger mechanism that the poundage will drop approximately two pounds & I will adjust the air regulator to the desired air pressure. Here is a pic of my set up. When you guys transfer the urethane clear from the quart size container do you dip it out or use a baster? The hardener & reducer have tip & pour openings.

corvecompressorairbrush005-vi.jpg

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...When you guys transfer the urethane clear from the quart size container do you dip it out or use a baster? The hardener & reducer have tip & pour openings.

Gary, personally, I don't use that quart mixing cup...that would waste too much clear. I have a 1 oz airbrush bottle dedicated to clear, that I have measured and marked to the correct ratios.

Edited by roadhawg
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Yea I hear what you are saying. Do you use a spoon or or something to transfer the clear from the quart container to your mixing jar.Here is a pic of my mixing container with marked level for each ingredient.I think that I'm going to use a large table spoon to spoon out the proper amount from the quart container.

AMT66Nova-vi.jpg

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Road, Say the gage at the start of the line the compressor is putting out 12psi at the one that is between the line and the air brush is at at 10. And why would you guys be shooting paint that high for? I'm lost at why you would have to shoot it at 35psi, but then I do not move away from Hot Hues line inless i'm having a special color mix and then its still Chromsystem line. The stuff is so thin as it is and I use a Paashe VL and also Iwata. And for the chrome Alsa is also thin like water..

I buy it by the qrt and then go to michaels and get the glass eye droppers in the stainglass section.

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Well, I shot my first model with Urethane clear today & it went well, I think. The car body is in the dehydrator & it looks pretty dog gone shiny. The mixing ratio .5-.25-to.75 worked out great so far. It went on wet even got a small run near the lower rear quarter panel.I took a q-tip & held it to the drip & it sucked it right up. Will post pic after it gas's out. Next time I will wear a long sleeve shirt.I have one heck of a ventilation system in my shop & this stuff really stinks. Be careful out there do like ED says.Protect yourself & take extreme caution with your lungs.Thanks you guys for all the help.

Jeff I apologize for taking over your thread that surly was not my intentions.

Edited by slapshot
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