tack coat

T

Treeslayer

Mike
curious, do most of you guys shoot a light tack coat before the heavier coats?
also, i have read on numerous occasions that spi single stage is just clear with pigment and should be shot as one would shoot clear. would this likely be the case with any modern urethane single stage?
 
thanks Don and Brian.
Brian, i know you cant really speak to other manufactures products, but your knowledge in the industry is greatly appreciated.
this is really an attempt at me understanding modern paint technology and terminology.
 
Real tack coats were used with acrylic enamel, synthetic enamel, alkyd enamel, and were used because subsequent coats would bite in to the tack coat and allow the tack coat to "melt" and would flow out. They were used to help with runs in those type of products. Urethanes are completely different and never require a tack coat. Urethanes and Polyurethanes do not flow out in that manner, so when a tack coat is used it just makes texture on the surface that you can't get rid of with subsequent coats.
 
Chris_Hamilton said:
Real tack coats were used with acrylic enamel, synthetic enamel, alkyd enamel, and were used because subsequent coats would bite in to the tack coat and allow the tack coat to "melt" and would flow out. They were used to help with runs in those type of products. Urethanes are completely different and never require a tack coat. Urethanes and Polyurethanes do not flow out in that manner, so when a tack coat is used it just makes texture on the surface that you can't get rid of with subsequent coats.
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that makes sense Chris. two things for me, one, i hope my newest spray gun acquisition helps me lay out the urethane better with out runs.
two, in future i need to pay attention to what products im looking at using besides SPI and make adjustments accordingly. remember some times im just painting trailers or equipment. on that note, i used to get this CAT paint for equipment, yes it really did say CAT on the can. im sure caterpillar didnt make it, idk who made it or what it was, but it did lay out good and proved to be very durable. havent seen it in years.
 
Treeslayer said:
that makes sense Chris. two things for me, one, i hope my newest spray gun acquisition helps me lay out the urethane better with out runs.
two, in future i need to pay attention to what products im looking at using besides SPI and make adjustments accordingly. remember some times im just painting trailers or equipment. on that note, i used to get this CAT paint for equipment, yes it really did say CAT on the can. im sure caterpillar didnt make it, idk who made it or what it was, but it did lay out good and proved to be very durable. havent seen it in years.
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Spraying a clear or SS poly/urethane correctly is easier than it seems. I've written dozens of posts here about how to do it. If you are getting runs you are either going to slow on your passes or putting out too much fluid with your gun. Often a combo of both. You want to have tight overlap (75%), and with each pass you are watching the clear or SS where it hits the panel. You want it to "fill in" and no more. You adjust your speed and fluid to achieve that. Once you can do that consistently you can lay down slick coats. Orange peel = too dry. Runs = too wet or too slow. Just takes practice.

As Kent White used to say, "if you can nail it perfectly the first time, congratulations. If you can't....hey welcome to the human race." He was speaking of something different but it applies to painting as well.
 
I sprayed a few completes with enamel in the 90's. It got a tack coat and could take care of any fisheyes and then it was hammer down.

First coat of urethane low VOC clear I put on a tiny bit lighter than my next coat. Always spray a closed coat, you will know it's not enough if it has small holes. I do my first coat either with more psi, less fluid or less overlap and sometimes a combination of the 3. It helps for the blend panels as the clear will run easier where there is no base.

I started spraying fast and close to actually get more control of the paint. I start too fast and slow down until the paint looks right. Can stop and take a look how it settles. Can always go back over what was sprayed to add more, cannot take it off when there is too much.
 
Chris_Hamilton said:
Spraying a clear or SS poly/urethane correctly is easier than it seems. I've written dozens of posts here about how to do it. If you are getting runs you are either going to slow on your passes or putting out too much fluid with your gun. Often a combo of both. You want to have tight overlap (75%), and with each pass you are watching the clear or SS where it hits the panel. You want it to "fill in" and no more. You adjust your speed and fluid to achieve that. Once you can do that consistently you can lay down slick coats. Orange peel = too dry. Runs = too wet or too slow. Just takes practice.

As Kent White used to say, "if you can nail it perfectly the first time, congratulations. If you can't....hey welcome to the human race." He was speaking of something different but it applies to painting as well.
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yes sir, i learn a bit more every time. im sure this new gun will be different, but i would think it has to atomize better than what i was using. i think my runs last time was my attempt to get it to fill in slick. i think i just couldnt ever get that gun to do that with out runs. we shall see, i might not like this one either, just have to try.
 
RosharonRooster said:
My friend Pete uses a binks7..
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How old is Pete? Got to be over 65 I bet. Guess he doesn't mind using a lot of product. Those things use nearly 2X as much. It was an old out of date gun in 1990 when I had one. I think the one I had was 15 years old at that time. Massive overspray. Old days using more wasn't the concern that it is now with the cost of the various products. I also hated cleaning a siphon pot and siphon gun. Very much disliked it. PITA.
 
Chris_Hamilton said:
How old is Pete? Got to be over 65 I bet. Guess he doesn't mind using a lot of product. Those things use nearly 2X as much. It was an old out of date gun in 1990 when I had one. I think the one I had was 15 years old at that time. Massive overspray. Old days using more wasn't the concern that it is now with the cost of the various products. I also hated cleaning a siphon pot and siphon gun. Very much disliked it. PITA.
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My friend Pete from youtube. He's probably late 50s...
 
Speaking of the devil lol
 

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Yep still have 2 Bimks #7 guns in my collection as well. Used one to spray a car trailer about 5 years ago with some jcheape enamel.
 
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