Paint gloss question

[Ctmodeler]

Sanded model car body with 800 grit. No primer. Spray bombed with Krylon . Result was uneven glossiness and could see sanding scratches underneath. Beautiful day out. Painted in direct sunlight . 65 degrees out 24 percent humidity . Can't tell ? percent if the scratches or painting in direct sun caused the issue. Sorry I'm a newbie. Lol what do you guys think ? It's cause it was in direct sunlight right ?? 

Thanks in advance 

Ken 

[Jantrix]

In a word.....

Primer.

There is no problem painting in direct sunlight. Those were near ideal conditions. Paint directly reflects your prep work. 

Sand, prime. Sand with a nice fine grit, gently. Reprime. Paint. 

 

[moparfarmer]

Maybe its me but 800 grit is too much..I never sand with anything under 1500 wet and always prime then sand again with 1500 wet or 2000 wet..Primer I use is Duplicolor sandable primer or Plasticote sandable primer..Both are lacquer based and you can paint all brands over it..Enamel,acrylic or lacquer..

[Snake45]

Your problem is probably that Krylon paint. You're asking a lot of it. Your results don't surprise me at all. 

Krylon wants primer, and then a couple coats of paint, and then will probably need to be rubbed/polished out. 

You CAN get a nice finish from a rattlecan of Krylon, but it's not just a matter of spraying it on and forgetting it. (There are very, very few paints you can do that with.) A good paint job is going to take a certain amount of work at both ends (i.e., before and after). 

If you can post a pic of what your model looks like now, maybe we can give you some advice on how to proceed. 

[Ctmodeler]

Can't really get the uneven glossiness to show up on a pic. Sorry . I'm using Krylon colormaster paint&primer in one. 

[Snake45]

8 minutes ago, Ctmodeler said:

I'm using Krylon colormaster paint&primer in one. 

Don't believe that "paint & primer in one" nonsense. Just marketing nonsense.   At least as regards model work. 

[Ctmodeler]

True true. I'm learning alot as I get back into this modeling gig ! That's for sure 

[Bainford]

3 hours ago, moparfarmer said:

Maybe its me but 800 grit is too much..I never sand with anything under 1500 wet and always prime then sand again with 1500 wet or 2000 wet..

It’s not just you. That’s exactly what I do as well. My primer is Tamiya. All sanding done wet. 

[slusher]

I use Krylon some but spray it on Tamiya primer.  Be sure you shake your paint really well. You have no idea how long I has been sitting on the shelf. You can never over shake it up.

[StevenGuthmiller]

There's a good possibility that the paint you used is a little too hot to spray directly over plastic.

The scratches and uneven gloss that you are seeing are very possibly light crazing.

A mildly hot paint will "raise" the sanding scratches and make them look much worse than they actually were before paint.

 

As others have said, prime, prime prime!

I wouldn't even consider spraying color over a model body, or any of the other parts for that matter, without priming.

Even with something benign like a hobby enamel, there are many benefits to priming first.

 

 

 

 

Steve

Edited May 15, 2020 by StevenGuthmiller

[Dave G.]

Yes, the solvents in Krylon can swell the sanding scratches in styrene plastic. It's better to prime. I don't believe for a minute it's the 800 grit paper alone but I don't use paper on my models anymore for overall sanding before paint. I either use scuff pads or steel wool. And I steel wool my primer coat with 000 or 0000 steel wool. Paper has a direct grit that digs in, pads or steel wool especially is a more scraping action. For me the results are great. Paper gouges and leaves microscopic ledges and ridges that the solvents expand. Just fwiw. But you probably would have won if you primed.

Edited May 15, 2020 by Dave G.