Paint runs

[junglemonkey]

So finally got round to painting my lunchbox, but even though I read the advice I still managed to get paint runs and the finish doesn’t look great. It was my first time at spraying the body and looks like I should have practiced on something else first! So anyway how do I go about fixing the paint runs? Is there an easy fix or have I messed up big time? Any advice greatly received. Thanks

[87lc2]

Of course it can be fixed, just takes the proper method and time.  First, you want to make sure you go down to the bare plastic in any areas with runs.  If you don't remove them completely the high spots will show up all over again in the new paint job.  I have found brake fluid to remove paint from ABS plastic bodies very well.  Test a small area first and if it goes well proceed with removing the rest of the paint.  Stay away from laquer thinner or harsh paint remover, it will most likely damage the plastic.

Once the paint is gone, scuff the body and clean thoroughly.  If not using paint with primer in it, lay down a coat of primer, then scuff and clean again.  When spraying color, spray 2-3 light coats followed by one heavier wet coat.  Don't try to cover everything with color on the first coat of color, that's when you run into problems.  

If you require a very glossy finish, let the paint fully cure then wet sand and polish the bodywork.

I'm sure others here will have good tips, but this is a good start.  I've been painting all types of bodies for years and the two most important things to remember are proper surface preparation and dont rush.  Good luck.

[StrokerBoy]

Patience is key, both in the initial painting and this remedy.  Sounds like you put too much paint on originally.  The good thing about proper ABS shells though is that you can fix this and no-one need ever know.

I'd wait until the paint is properly dry before sanding it back, rather than taking it off with brake fluid or similar.  Could take ages, especially if the runs are bad.  But sand the runs down until they're gone and everything is nice and flat again.  You don't have to take all the paint off, just the bad bits.  It'll have to look worse before it eventually looks better - don't worry.  You can feel any high-spots as much as see them.

Once perfectly smooth, start painting again.  Spray a thin coat, don't worry if you can still see patches underneath.  Repeat with thin coats until it's consistent everywhere.  Take your time.  Good luck, and put some pics on here when it's done.

[junglemonkey]

I’m assuming I should use a very fine grade sand paper to sand back the runs? Otherwise i’ll scratch the plastic with a course sand paper! The runs are mainly situated towards the bottom of the sides so could I use terpentine to remove them? It’s a cheap bottle I use to wash out my paint brushes so nothing too harsh. Just asking as I have a bottle of this already but don’t have any fine sand paper to hand!

[StrokerBoy]

Use fine wet&dry paper rather than the rough sandpaper you use for the skirting boards in your house.   But the principle is the same.  Get it from Halfords or a decent DIY shop, maybe even your local poundshop.  The smaller the number, the more coarse it is.  If you do scratch the shell, you can fill and sand it to restore it, but you don't want to be going round in circles forever.

I avoid solvents 'cos you need to be sure they've totally gone before you start painting again, but some people prefer that approach.

[Prescient]

11 hours ago, junglemonkey said:

So finally got round to painting my lunchbox, but even though I read the advice I still managed to get paint runs and the finish doesn’t look great. It was my first time at spraying the body and looks like I should have practiced on something else first! So anyway how do I go about fixing the paint runs? Is there an easy fix or have I messed up big time? Any advice greatly received. Thanks

You need to flatten the runs back.

Do not use chemical strippers, these are only really necessary if you have multiple paint layers often of different colours and paint brands and major issues as a result i.e. paint won't set properly.

As you are UK based, the Titan 1200 and 600 grit wet and dry from Screwfix is by far the best value for quality paper. 

1200 should work and gives a great smooth finish. 600 will cut through the paint very quickly and makes very short work of high spots if needed. 

https://www.screwfix.com/p/titan-wet-dry-sanding-paper-230-x-280mm-1200-grit-pack-of-10/98101?_requestid=163687

With Tamiya TS paints very light coats in layers is the perfect technique. If you get runs your spraying too much or have flow issues which is a downside of rattle cans. Make sure you warm can in warm water first and between coats. 

The lacquer/gloss effect from Tamiya TS paints will start to show as the paint cures and it should look matt after initial spraying. If it looks glossy on application you may be spraying to heavily. 

If using another brand of paint consider swapping to Tamiya but you will need to prime over the other paint after smoothing with Tamiya primer. Different paint brands can often react. For example Halfords automotive paint and primer does not agree with Tamiya in my experience and mixing inc the lacquerer prevents full curing occuring. 

[topforcein]

if you plan on useing it for bashing then i would'nt bother with the run tbh as the shell will at some point flip over and scratch thus the paint job will be ruined anyway.

[junglemonkey]

Well I sanded the drips back with the suggested paper and sprayed again, and again and again, and finally managed to get a finish that I was happy with. I’m not sure why it took so many coats before it looked ok, but I got through 2 and a bit cans! The paint just didn’t seem to take. I warmed it, shaked it etc etc but I got there in the end. Here are a few pics of my first paint job along with the finished beast!

 

[topforcein]

and another beautiful lunchbox is born.it looks great well done