This thread is for Joey K

[eric99gt]

Joey I will be soon getting the sc/t kit for my car. My buddy will be painting it and at the same time repainting my front quarter panels because they have some scratches. Heres my questions....do urethane body parts require any sort of special instructions besides just mixing the paint and spraying it? Also the quarter panels any special tips as to prep work, same goes for the kit? Only reason I ask is because he is really good at laying the paint on just sometimes forgets about basic prep work. Like when we painted my sd hood, since it's fiberglass we had a real problem with the paint not sticking. Like we left it sit for 2 weeks after we painted it. looked great, get ready to install, the paint just is a pile of goo. I could push on it and put handprints in it lol. Well sorry for the long story but i really appreciate the help. Thanks

[JoeyK]

For the prep work-Just make sure you wash everyting to be refinished down w/ wax & grease remover, feather out all your knicks & scratches w/ 320 grit or finer & don't forget to use a tack cloth just prior to painting. Urethane panels prep just the same as fiberglass or metal. There's no special rules for prepping Urethane, just treat it the same as amy other panel.(it's just more to difficult to repair damage on a urethane panel)
Now, for the important part, the Paint- Urethane body panels, as we all know by now are very flexible, especially when warmed. This is where some people get into trouble. Because or the expansion & shrinkage due to temp increases/ decreases urethane body panels will crack ordanary laquers & enamels unless a FLEX ADDITIVE is added. You can go w/ a laquer or enamel if you so choose, but I must warn you, the flex additives are not all foolproof. I've seen some mixed w/ the propper amount of additive & still crack! That's why I highly reccomend urethane paint. Urethane paint will stay flexible, although it may seem tough as nails to the touch. here's the differences in the compositions: laquers generaly have a chemical & pigment compoud, with a binding agent added in. Enamels generally have chemical, pigment, binding agent & cereamic compound. Urethane, on the other hand is ideal w/ chemical,pigment, binder & urethane plastic compound.
So as you see, urethane paint litterally has (urethane)plasitc in it. It is this property that allows it to remain flexible & is the primary paint type used in the automotive industry today, not too mention many other industries.
I assume you went w/ urethane on your hood? w/ urethane paint you have to have (assumeing it's already been reduced, or thinned for you by your jobber/paint supplier) hardener(catylist) & accelerater. I assume you either had the wrong ammount of additives, or just missed out on putting one or the other in. I too have accidentally done this before on a semi truck doghouse- man , what a mess as all you can do is wash it back off w/ reducer or thinner & start all over again!
So in a quick recap: Treat your fenders & sct kit the same, prep by washing down w/ wax & grease remover, feather out all your knicks & scratches, make sure you finish sand w/ 320 grit or finer, wash down again & then tack off prior to painting. - Use urethane paint & mix EXACTLY to manufacturers instructions!~ VERY important!
If you can tell me what paint you useing (PPG, Dupont, etc. ) I could even help you w/ any questions as far as mixing & application. untill then good luck, I'll try & keep an eye out for any other questions.

[eric99gt]

Hey man, post greatly appreciated. I'm not sure what they used to paint my hood because i had a bodyshop do it, but so far it's holding up well even through our harsh winter. The paint I will be using is PPG. My buddy likes spraying that on. Once again thanks alot for the help.

[eric99gt]

hey joey u have any advice on mixing for the ppg paint....thanks
also any special painting instructions for the urethane paint

[JoeyK]

Just be VERY precise when mixing, follow the instructions on the label & be aware of the temp & humidity. Believe it or not, high humidity makes urethane kick faster. There are fast, med & slow reducers & fast & slow accelerators. which ones are right for your application depends on your climate & the temp your painting at. High heat & humidity you'd want the slow reducer & accelerator, nothing worse than the paint hardening on you before your done. On the other hand, if it's somewhat cold, like 70 degrees, then you'd want the fast. if that paint takes too long to harden the more of a chance it will have to sag & run. You'll just have to play w/ your spray gun setting for the amount of material feed, everyone paints different. (Different speeds, diff. size strokes, etc.) I set my air at 45 psi & set my material at 1 ounce/15 sec. out of the gun. Make sure you test spray on something to ensure your set right before you shoot your parts. Also, incase you don't know, spray as long a stroke as you can & keep an even pace, about 8 in. off the panel & overlap every stroke by 50% You may want to "Spot in" any tricky contours first, then keep an even stroke over them as you come accross them while painting the rest of the part. ~ It may take two to three coats to cover the parts, stop when it looks correct~ Don't try to get it covered all at once or you'll end up w/ runs, just make sure you have good wet, even coats. (Also, people sometimes brag about how many coats of paint they have on thier car, ignore that. You only need enough to make it look correct, unless your gonna wet sand it to a morrir finish, then maybe you'd need 5 or 6)
Oh, ya one more thing, most people think accelerator is optional, w/out it it could take hours or sometimes days to dry. Make sure you put accelerator in the mix, there should be instrucions on that can also.
Hope that helps, kinda seems like I was rambleing onbut oh well, atleast most of the info. you'd need is there:)