Not sure if it's the humidity or that the paint I used wasn't really for plastics (ordered paint online that matches body color).

I fine-sanded (2000 grit), used adhesion promoter and the paint stayed on, didn't run, then sprayed layers of clear coat. Why is it grainy

Of course, I'm going to paint it again. At this point, how should I proceed? Rough-sand the paint? Use plastic primer? Paint with plastic paint from local stores?

 

If your are applying the clear to the piece while it's laying on a table it will not work.

Also have to pay attention to the distance from object being coated. Too close and it will run and could even re-blend the paint making it look wavy, too far away and you will get a textured semi gloss or matte look.

If possible, do two medium coats of clear then one heavier coat to finish it off for a nice glossy look. Object should be hanging up secure from a coat hangar so it doesn't spin around while spraying it.

 

..I know just what you speak of, not long ago I got a stock S roof spoiler to put on our justa, but it was BRG, so I ordered the factory black roof paint and clear..

..I hung it with a coat hanger..as grayraven points out..& the painting went well...but really grainy ..then took another look at the can of clear..it indicated need to buff out to get smooth & gloss..

..so (waited a few days to fully dry) then careful wet sand..then LOTS of time with rubbing compound..& it finally came out glossy as roof
J

 

You need to wetsand with 2000 grit between coats. I do this process:

Prep- Clean, sand the piece with 600 grit, then 1000 (make sure you go both directions.. cross hatch), wash with detergent (do NOT touch after this), dry with a blow dryer on cool air (towels tack dust to it), or you can wipe it down and wipe with a tack cloth afterwards.

Paint-Plastic primer, very light coat of paint (literally be very patient as its so light), let it dry, put on a medium coat, let dry, wet sand with 2000 grit, dry with process above, then (repeat with how many coats you want), I just do a medium-heavy coat here to get a nice gloss. Dry, wetsand with 2000 grit VERY lightly (just to get the surface smooth from paint spray imperfections). Do you sand too hard, or you'll be left with white dust in the paint. Next, use polish compound (one that you use with on the car would be fine, it can be pretty abbrasive, actually helps the finish), and polish the surface well (use some elbow grease). This will bring the shine back after sanding it.

Clear- Make sure you use appropriate clear with the paint you used. If its acrylic, use acrylic clear, etc. You can look up on google when mixing combinations is ok or not, say with enamel base and acrylic laquer clear etc. Make sure the paint has dried VERY well. This means all the under layers as well. Give it AT LEAST a day in the perfect conditions, otherwise a few days would be best (if you can wait that long). The reason I say that is the clear can seep through the paint and cause havoc. Spray a light coat of clear and two medium coats, with light wet sanding in between. Finish off with the polish compound and wax.

Good luck, takes practice but you'll get it.

Use sweeping motions with the spray paint, starting before the piece and following through after the piece surface ends. Cover from overspray, use ventilated area, suspend the piece. Clear your can nozzle after by holding upside down and spraying until the paint runs clear, to minimize clogging for next use.

 

Thanks for the replies! Didn't expect it as it is Super Bowl Sunday and all

I took most of the steps you all described in the same order. Except for two things and these probably are the most crucial: I didn't hang the pieces, painted them on the floor and I didn't wet sand and rub with compound afterward.

At this juncture, should I a) wet sand and polish, or b) wet sand, hang the pieces, apply a few more coats of clear, then wet sand and polish?

Like I said, paint is on, not runs or sags. It is kind of glossy, but grainy.

 

I haven't work on it yet

Just doing what I should've done in the beginning which is attach pics. This is how the trims look a.t.m. See how grainy it is?

 

...if you have the clear on there pretty thick, you could try to carefully wet sand (careful w/the edges)..then compound/polish...& see how it is looking/matching up

..& the thing about hanging it up..cause on the ground/table...it can blow dust up...& the paint/clear..can kinda make its own sorta dust..

...and if thats not getting it there, no harm done..& maybe then need some more clear...but then of course you gotta wait till that dries...and still buff it out to shine right.

..its gonna take a lot of elbo grease with the compound/polishing.
..when I went through all that with the spoiler I did...was tiring...cardio with the arms
..good luck..have fun..& update us with the pics.
J

 

Looking at the photos the matte is caused by your clear coat not being thick enough. After this is dried, lightly wet sand with 2000 grit, dry, and put a medium-heavy coat of clear on. Make sure that it doesn't drip/run, but make sure theres enough to the point where it actually looks wet / glossy. Wait another day or so with the part inside, and then use a car polish on it, work it in good, wipe, and then apply wax.

Be forewarned though, don't get upset if it chips within a few weeks. With the rocks/pebbles/sand/debris that gets kicked up cars infront of you, it'll be very easy for the paint to start chipping. I had plenty of chips after the first week.

I had originally used plastidip, and that didn't chip, but it was also a matte black. After a year it had faded so I sanded it down and used krylon fusion for plastics, with primer/adhesionpromoter/clear, and after a week there were many pits in it from debris. I eventually just bought a used JCW grill trim and never looked back. Good luck though, you may have had a better process that'll work better, or even, just better roads. haha

 

Definitely on my list of things to do, but not until after I do what BostonR56S suggested.

Really? Even with a coat of wax on?

I started with plasti-dip myself. I wasn't very satisfied; the matte trims against the glossy black was just an eyesore. Before that I tried DIY vinyl, but I lacked the skills for complicated shapes.

 

I'm resurrecting the thread I started.

I eventually figured out how to recreate that glossy automotive finish on my chrome trims, thanks to tips posted above and this youtube vid. I was quite easy; it just takes time.

The problem, however, as BostonR56S has pointed out, is that the front pieces are prone to chipping. I was thinking of protecting them with a coat of epoxy resin, but I'm not sure if I want to go through the trouble as there's no guarantee that resin won't chip or crack.

My advice to those who are serious about a black-out mod is save your money and buy the JCW grill trim and the black headlight and taillight trims sold by newministuff. Vinyl wrapping is another option, but I don't know how a thin layer of vinyl will hold up against pebbles.

 

The 3M protective film will help with chipping but if anything you would probably do the entire front end. Resin is a tough thing to use because it could easily yellow or crack in heat. Vinyl wrapping is a great option. VERY durable over time, very cheap. And if for some reason anything happens to it you just wrap it again.