Question re: Spray Painting 101

[Bill Yonescu]

I'm new to this forum so I hope this is the right place to post this.

I just finished watching SP101.. I liked it.. it was informative to me in many areas. While I probably have many questions, the one I hope to be answered is, while I am waiting for the first light coat of paint or clear coat to set up.. (said in the video to be about 10 minutes) does the paint in the spray gun need to be removed from the spay gun and the gun cleaned? .. Won't the gun clog up in the 10 minutes???

Thanks in advance,

Bill Yonescu

[Phil V]

The paint setup time in the gun is usually at least an hour, in many cases at least two or three hours. So no, you don't have to empty the gun in between coats of paint. A good logical question though.

[AutobodyCAD]

and as far as flash times (or curing for stuff with hardener/catalyst) remember to pay attention to the data that comes with your particular products... not the examples you see in a video or hear from a friend.

some 2K etch primers have a pot life of 24 hours or more. Some poly primers have only *minutes*, which would make your paint gun a $well paper weight.

[Bill Yonescu]

Thank you, both, for your replies...

I'm a wooden boat builder familiar with epoxies (adhesives, not paint) that "flash" or cure much faster when in the "pot" than when on the boat and just wanted to make sure that the spray gun would be OK...

When the time comes I'll be sure to read the product information.

Thanks,
Bill

[JoelF]

So does the 10 minute flash time start after finishing spraying or when you start?

Reason I ask is that if you are painting a Harley tank it might take only a few seconds to paint the entire tank, whereas if you are painting an old Chevelle it might 15 minutes or more to spray a coat.

In these two examples, the Harley would be getting it's second coat 10 mintues after the first, while the Chevelle might have its second coat laid down 25 mintues later (15m to complete paint coat 1 + 10m flash = 25m between first and second coats on the first panel painted).

Does this make sense? Or is it unimportant so long as flash time does not exceed X minutes?

[Phil V]

Joel, it definately makes sense. the recommended flash time is from the time the last of the paint is put down in that particular application sequence.

[Len]

I usually judge the flash time by how DRY the paint is rather than by the recommended flash time. The time before the next coat can vary widely depending on the paint, solvent and temperature so judging by touching can be much more accurate than a recommendation in writing. I allow the paint to "dry to the touch" after my first coat, and after I apply my second coat I allow it to just sit for until tacky before applying my third, if a third is required.

I try to touch a spot on the painted surface that will not show when the vehicle is assembled because touching the masking material is usually not an accurate measure of the condition of the surface.

[JoelF]

Thanks guys. For some reaons this question always nagged at me.

[yousif]

[B]dear bill

as you are a boats builder you must know this trick
in hot summer you add little hardner to your resin and in winter
you add more hardner to your resin to create fast chemical reaction

I were a boat painter for long time and been dealing with marine
poly primer, expoxy paints and building fibre glass racing boats
but now I switched to cars painting

but I had a problems only one time when I mixed fast sikkens hardner
which been recommended by the paint shop:rolleyes: . I applied the first wet clear coat on my boat custom painting
and after around 10 minuts I shooted the 2nd coat...but had asmall dirt. nips..created by the fast hardner
and spoiled all my finish, I called the paint shop and after that they
provided me with free paint with a normal hardner but I stopped buying sikkens paint :confused: and switched to spice heckers germany
and feel very happy with it