Help on simple bumper painting. PLEASE

[Geneman]

Hi Peeps. I suck at this stuff. but must bite the bullet and giterdone myself before heading to sebring next week ....

Simple new IROC bumper. ( in fact i had to shorten it myself, taking out about 3 inches in the middle, reglassing, then glaze, prime, sand etc.. its prepped pretty well. I think will take a last 3M wool to it before paint )

I have a pretty high quality HVLP spray gun, gravity fed. but do not know how to use it.

Its single stage Genroc paint. you add the activator, and strengthening/flex solution to about 10% . that i can do. I got medium speed activator. its about 50-60 deg. here in philly.

Before i use this paint ( the good stuff ). how do i setup the spray gun ? can i use some soivent. or other junk paint to get a good pattern? The gun was all clogged with dried paint when i got it out from the last debacle, so i had to dissemble soak it. clean every friggin orifice..

I do not want to have the paint dry again inside the gun.

So if i do the first coat. Must i then pour the unused paint out, clean the gun completely with solvent. Let the paint dry. Then remix and do the whole thing over again for a second coat?

i get the entry pressure: 20-30 psi at the meter on the gun. How to you set the two adjustable dials on the gun: seems one on top is for paint volume, one on bottom adjusts the pin where the paint comes out and fan.

how much do i thin this for use in a gun?

what kind of paint can i use for a trial run to set the gun up ?

very much appreciated

[962porsche]

looks like LRP to me.
I go to the tracks at least once a week many times twice a week between instructing and racing. I just counted the amount of times I was at LRP this past season. 16 times my last day was on the 20th the other day. 3 hours of open track time.

how I set up my guns
I 1st adjust the pressure into the gun I tend to do this by feel more then what a gauge is telling me but in general it's about the 20 to 35 LBS much of this depends on the viscosity of what material/s I'm spraying.
from that point when you have the pressure set about where you want it you can adjust the spray pattern . you want a nice oval pattern. no dog bone shape or to round.
if the pressure is to high the pattern will give you a dog bone shape.
if the pressure is to low the droplets out of the spray tip will be to big.
to adjust the gun I do it with the product I'm spraying at the time. again it's has to to with the viscosity of the product your spraying.
for the 2nd knob down from the top of the gun or the needle adjustment.
I back the knob out almost all the way.
then I pull the trigger of the gun so it's hitting the handle. I then screw in the knob until it just pushes the trigger away from the handle with me still holding the trigger.
different painters will set the trigger up for there own liking but this is the way I like it.

with the genrock paint they will have what is called a TDS ( technical data sheet ) this will tell you what tip size you will need to spray the product , what pressure, what the reduction ratio is and so on.
as for needing a flex additive it's not needed at all ! you have a fiberglass bumper unlike a soft plastic or rubber pumper there is no flex in the substrate. if your thinking like many that it will help in the bumper to not get chips in it . this is totally untrue and a total myth!
a flex additive is for the flex of a bumper in cases were say it gets pushed on or pushed in so the finish will not delaminate or flake off. it does nothing at all to guard against chips or scratches.
guarding against this comes from your prep work and under coats you use.
the TDS for your products will tell you things like what grits you will need to do your final sanding in. how many coats to apply if you need a primer or sealer under your top coats. a sealer in many cases is a good idea .

when it comes to the between coats thing.
you spray your top coats in what is called wet on wet. it's referred to as flash time/s.
you would spray your sealer in your case with the color your spraying I would go with a white or very light gray color. this will help in adhesion and hold out so any sanding marks will not show after the paint cures.
from the sealer going wet on wet you would let the sealer dry for about 15 to 20 minutes ( check the TDS) in that time you wash out the gun with some thinner and get the paint ready to spray.
once the sealer flashes off you then spray your 1st coat of color.
only mix enough color to spray one coat at a time.
there should be no reason to clean the gun the paint should not dry or set up in the gun between the coats.
figure out how much paint you used on the 1st coat and only mix enough to do the next coat so your not mixing lots more than you need.
after the 1st coat has flashed off in most cases it's 15 to 30 minutes you spray your next and this should be your last coat.
after your finished spraying you then clean the hell out of the gun. and spray some thinner thru it to be sure it's nice and clean.

an easy way to see if your paint has flashed off and it's ready for the next coating take a 6" X 6" piece of cardboard and cover it with masking tape.
the reason for the masking tape is because if you just sprayed the bare cardboard the solvents would soak into the cardboard and seam dry when the bumper is not.
when you spray the bumper with each coat also spray the masked up cardboard.
you will know for sure when it's time for the next coating by placing you finger on the painted cardboard. if paint comes off on your finger then it's not ready for the next coat.
what you want is to be able to touch the cardboard and leave a finger mark and have no paint come off on your finger. when it's like this it's time for the next coat.
flash times are given for a temp of 70 degrees F but it's not the air temp it's the temp of the panel your painting that is the 70 degrees.
so if the air temp is colder that will make the panels surface temp also colder. this will increase the flash times . in some cases it will increase the flash times greatly.! so in the ads it may tell you 15 minutes between coats but in your garage it could be up to 30 or 40 minutes between coats. this is why the finger test is important.
I hope I'm covering your questions?

[Geneman]

Wow. great to hear from you. 962! Its Frank from Philly. we corresponded years ago about paint when i was just starting racing. ( in fact I lived in Branford for a few years ( right near short beach) while at grad school at Yale.) one of those vacation bungalows with NO insulation..friggin cold! You told me you stopped painting for the general public long ago..

i just did this about 3 hiours ago before reading this. However, turned out pretty close to your instructions. I buffed the gelcoat with 320 then sealed with rattle can high build grey primer. two coats. However, i did not continue color when the primer was flashed. instead. let it dry o.n., 400 dry sand, wipe with solvent. ( the wax/greases remover) . then mix and apply paint.. after many videos. i set gun up with about 30-40 pounds intake then 10 psi at pin. The genroc i added 10% flex ( good to know its not needed ) and 0.2 part thinner. to me it was pretty thin. but surprisingly, i seemed to get sprayt that was too big. also, it came out pretty slowly .. but seemed if i increased paint flow, it increased spray size (droplet size). However, even thiough droplets seemed to land large, they seemed to meld together on the surfsace and even out nicely. had to put gun pretty close to bumper and move gun slowly to getr coverage. also issue is that its about 45 degrees ambient here... I let it flash for 30, min. then another coat ( did not do the cardboard thing but really helpful to know). it was definitly sticky when i started 2nd coat.. cleaned gun in between. I was surprised how much paint one bumper could take. almost 2/3rds of a pint for both coats. it will dry O.N. outside ..so could take awhile with temps. I have some heat lamps but not sure they would do much. i learned gun cleaning is critical , which i had not been doing thoroughly in previous trys. now i must decide what to do for after-sanding and buffing. this single stage paint must have clear coat in it. so i do not know if i should post sand buff this fo orange peel , which there definitly is, as if it were real clearcoat .. thanks again for all your help. i have printed your response/instructions for my DIY bible!

[Geneman]

Yes indeed : LRP. this is a member day. last tuesday. i was a guest .. 70 degrees and beautiful. we lucked out on the day. great group of people. I met Simon Kirkby.. great guy .. he rode right seat with me and helped ALOT.... very nice guy and incredible racing experience. I got about 5 events at LRP this year, despite covid... my brother from Ridgefield CT has started track stuff with his 964 and he is addicted. hoping to get him race certifired so we can have a team. I have Been PCA Club racing now for years ( along with SVRA, SCCA, HSR etc). hope you are enjoying retirement!