Hey paint peeps! Couple quick question regarding Acrylic Urethane. This is the first time I've used single stage Acrylic Urethane. It will be shot over properly prepared epoxy primer and sealer. I'm spraying a hot rod frame and when laying primer it took me approximately 25 to 30 minutes to get every nook and cranny for each coat. The primer flash time with the 70* working temp worked out fine as long as I kept moving and paid attention. NOW! The flash time on the AU appears to be 10 to 15 minutes, according to the spec sheet. That's essentially faster than what I will be laying it down. I will be using "medium" reducer and ambient should be around 70-75 degrees with about 30% humidity. Will I be okay to simply go from one coat right into the next, or can I let it set for a bit before laying down the next "wet coat"? ALSO! Being this is my first time shooting this stuff, I have a feeling I'll be fixing a run or two and who knows what else. Going to follow the great tech on here for cutting runs in AU, but can AU typically be cut and polished if I have a little overspray or orange peel? Or am I forced to knock it down and shoot again? Just trying to plan ahead for my paint schedule and supplies... Thanks!
Read thru this: http://www.jalopyjournal.com/forum/showthread.php?t=308529&highlight=acrylic+urethane+death . And be careful! . . . .
I cut and polished AU before. The touring had a fair amount done on it. On the T frame, by the time I had to reload the gun and get back on it, it had tacked enough for another coat. This is coming from a home painter that paints once every 5-10 years, just what works for me. I did learn from a pro and worked in his shop in HS so there is some residual base I am working off of.
YES! Important safety tip for the day! I don't think it can be stressed enough to be careful when working around this crap. I sprayed some gloss black Polyurethane recently and used a SUPPLIED respirator and still felt a little bizarre at the end of the day. No complications to speak of, but the polyurethane tends to pass through the skin, eyes, and of course the lungs. I'm going to use a supplied respirator again for this. Sort of a pain to drag the hose around along with the compressed air hose for the gun, but I would rather be safe than worry about anything I read in that thread! I think this subject rates right up there with "Don't Cross the Streams!"
Ok Scooter, the safety issues have been fairly well beaten into your eyeballs by now. That link to the other painter was scary huh? Now I will try to answer your questions the best I know how. Flash time-my experience is that epoxy primer flashes faster than urethane top coats. Let's refer to this from now on as just color. The color will get sticky as all get out as it drys/hardens. The epoxy primer just seems to flash dry and get dry to the touch. My advice is that the issue you will have when you are working your way around the frame and try to spray color adjacent to an area you started out at, the fresh color will not blend into the not so fresh color. That's because the color started flashing off and getting sticky and the fresh color doesn't properly dissolve into it. Solution- spray that frame from one end to the other and try to work in such a manner that you are never spraying next to color that has laid on too long. Your ambient temp will also contribute to the color getting sticky quickly. On the other hand your ambient should allow the color to flow beautifully. In answer to the second question about going from one coat right into the second, if the paint is sticky to the touch but does not pull strings when you touch it then it is ready for another coat. It is likely that by the time you finish one pass on that frame, and with your ambient temp, the frame will be ready for it's second pass. Do the finger touch test in a hidden area. In my opinion, if you wait too long and it goes from sticky to merely tacky or not tacky at all you have waited too long and you don't get the best adhesion between coats. Of course it will still work but I'm trying to give you the best case scenario. In reference to your other questions regarding cutting and buffing. AU has a kinda narrow window of opportunity for best cutting and buffing. If you start sanding too soon it balls up in your paper. If you wait too long it is literally like trying to sand rock. Urethane is funny in that it always remains somewhat flexible but it also cures really hard. I would wait about 24hrs or so before sanding but not any longer. In other words, please don't try to paint it one weekend and then try sanding it the next weekend. With your temps down there it wouldn't be any fun at all. To answer your question directly, yes AU can be cut and polished if you have a little overspray or orange peel. Be aware though that uncut AU is very very glossy and if you only cut and buff some areas and not others they likely will not match in glossiness. I would like to recommend shooting the inside areas of your frame a little dry to absolutely minimize chances for runs. Just don't go too heavy with the paint when trying to get it to lay down super smooth. Fixing runs and buffing on the inside of the frame would be a major PITA. On the outside and other areas that are readily seen, go ahead and try to lay it down a little more wet to get that super attractive flow and smoothness. Also be aware that AU and your temps will flow after you shoot it a little. So what looks perhaps a tad rough right after you spray might lay down some with a little time. Okay that's enough. I just wrote a book. If you have more questions just ask. Joe
Joe! Thank you! Perfect! I believe that about clears that up! To add two more questions... - Should first color coat be merely a tack coat or should I let it flow? (with respect to your above reply about inside and outside of the frame) - In the event of orange peel after it sets, what should I start and finish with? (i.e. 1500 then polish or 1000, 1200, 1500, then polish) Thanks for the long response! Good info right there!!!
Scoot First coat should be a medium to light coat. In the old days of lacquer and enamels we shot light tack coats so the first coat would not run and so the other coats would have something to stick to. AU is soooo freaking sticky that you will not have that issue. Of course you don't spray it like the following coats, just not as lightly as a true tack coat. Once again, just my opinion from lots of AU and other types of spraying. Okaaay, so sanding grits huh? Part of this depends upon how cured the paint is when you try to cut it. BTW when you start sanding it will outgas a little more as you just broke the outer skin so be prepared for some smellies. Personally I am sick in the head and love the smell of most paints but that's not for most people. In answer, I would start with 1000, then 1500, then 2000. For the areas that are really seen and if you want them to be tits on a ritz beautiful then finish with 3000. Yeah, I know it's like sanding with binder paper but it does make a difference. The buffing will happen much quicker with the finer grits of paper you use. I also use 3M buffing and polishing products. What are you going to use? What color are you squirting?
WOW! 3000! Crazy guy! I get it though, for sure! Guess I didn't realize that the polishing compounds would be any better than that. Wow! Someone told me here at work (he shoots linearized acrylic polyurethanes, he thought) said that the single stage AU's fall into sort of a base-clear suspension, but I didn't think that was the case. Aren't they the same make-up all the way through?? (In other words, it's not like polishing through a clear coat and then having to reapply it) I didn't think that was the case with the AU colors. The color will be pretty dark, so all my mistakes will be seen. By the way, I've been looking for this for the last couple hours and finally found it! Bill (Slowandlow63) have been a huge help in the past and this thread is awesome: http://www.jalopyjournal.com/forum/showthread.php?t=367250&highlight=tech
I think a polished frame tends to look a bit too fake for nearly anything, but I have a restoration mindset. That said, what I do for frames are 2 pretty simple and borderline obvious things. I start by cutting in all the tough spots. Like triggerman said, even if it does dry a tad bit too long it will still bite in and hold. So, do a good cut in everywhere that it'll be a bitch for the final pretty coat then paint the whole frame nice like you're looking for and overspray won't be much of an issue. The second thing, and I'm pretty amazed how often I see it opposite, is I paint the frame upside down for the final coat because that's where you see it the most...UNDER THE CAR. Now on our beloved hotrods we sometimes show more of the thing but who's ever going to see the spot where the body bolts down? There's another trick I do but it takes 2 engine stands. I bolt up a piece of angle front and rear with a tube the right size for the engine stand welded in center. You can use a bolt with a polished tip on it for the lock down hole and snug it just enough to be a damper for safe turning. I do this on big 11th series Packard frames with great results and yes, thos big bitches will spin 360deg on a conventional engine stand. However they're so big and heavy I won't spin em alone. Take pics and show off when you're done.
Highlander, I totally agree about painting the frame upside down. It should be obvious to most of us but it usually isn't. Scooter, 3000 only if you desire that super smooth, not a single sanding scratch finish. I glanced at the link you posted and it looks informative. I'll read it later. 3M makes a Trizac(sp) sanding system where you can buy sanding discs that attach to your DA sander and use them wet. I use them and the paper last a lot longer but the initial buy in is steeper. On a body it's a hell of a lot faster than hand sanding but may not apply to your frame. In my experience sanding AU, I have never seen it layered. As soon as I start sanding, color starts sluffing off. However, like I stated before, it drys super glossy and takes one heck of a concerted effort to buff out to that same level of gloss. Dark color will also determine which polish you use especially if you use the 3M line. Yes, it will also show EVERY LITTLE FRIGGIN' MISTAKE. Just remember now, I'm helping with your paint and you're gonna help when I rebuild one of my hemis right? LOL
Highlander... I totally see the whole thing on being "TOO GLOSSY". And frankly I agree with that very statement based on the application I have here. I know AU has a tendency to look plastic-like, so if it's possible to get around that, I would like to. This is a driver and not a show car. Only the front couple feet of the frame rails will be seen as well as the very back of the rear cross member. That's it. The rotisserie thing was something that I KNEW I would need for this frame with all it's tight spots, so I built something that would be easy to work with. Worked GREAT for the primer! Plus I have plenty of future projects I knew it would help with. (This is pre-primer before filler work was finished)
I don't know if it is in the thread of Bill's that you posted but I believe he and others tend to cut the last few coats with clear to give it less of a plastic look and more of a lacquer look. You should ask him but I seem to remember they do it up to a 50/50 ratio.
LMAO, cool. That rotisserie looks killer dude. If you want your AU to look a little more enamelly (can I make that a new word?) then just don't sand it as fine and don't buff it as much either. The finer sanding and the more buffing, the shinier the paint will become. Try stopping at 1500 and buff lightly then go for a polish. When I did a '69 Camaro it looked like oxidized enamel after just sanding with 3000 because it had a sheen without gloss or much shine. That was an AU job BTW. It was/is painted Dover white and Hugger Orange. I don't think I should post a pic of an OT car but can PM them to you if you want to see what is possible.
That thing is way cool. Seems like good tech week material. You need an oompa loompa to slowly turn it for you while you paint. +1 for 3M trizact although I use it dry, not wet.
Hey Scoot, On shootin a frame in acrylic urethane.................... I'd kick up to a slower reducer given as hot as it's been, and the fact that I'd rather walk through hell on Sunday than coloursand a frame with as many cutbacks and returns as that one! Flow is the name of the game, and makin the product work for you, not the other way 'round. I'd use a detail gun in those tight, inside corners, and lay down a full wet coat on the sides & tops of the rails. I love the big fat fan of an old #7 ( The SCAQMD will have to check me in action before I'll swing from the rope) for flow and speed on something like this. Given that material is usually cheaper than labor, this works for me. Spending many hours sanding out dry peel and tryin to wheel out a passable finish would probably drive me to the passionate embrace of a bottle of Austin Nickols! If you're gunshy 'bout ''hangers'' & "sags" jump up on your game and do a workout on some bike frames or sheetmetal parts. Work on your triggering and gun control (the only good kind of gun control) and build up that skill level. " Beware the irrational however seductive "
Yes, thanks. My observations are purely from the hobbyist side of things. Nice to hear confirmation from a painter. I did a cycle and dulled it down quite a bit. On the last car I only buffed until I had a nice gloss, not plasticky looking. Might have taken it to 8 or 1200 before buffing it out.
Yep! I have a little detail gun ready to go! Good tips, as always! The other good thing is, only about the front 32 inches or so is going to be seen, and a little of the rear cross member. I've been spending LOADS of time on the flat sides of the rails and tops to make sure they are good and flat and not wavy. Lots of blocking! So I think as long as I can keep my guns under control I'll do all right. Been practicing quite a bit. I guess we'll see if it was enough! (YIKES!) Seriously some very good tips here!! I really appreciate everyones input! I'm very excited to be to this point! Been five years of hard work to finally get to this milestone... The final color! Now where's that bottle of... LOL! Thanks again everyone!
Have to lay color on Sunday! We are going to assemble the rolling chassis over Labor Day weekend, so I'm hoping everything goes smooth! Fingers crossed!! There will DEFINITELY be pictures!!
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