How do I avoid this?

[stonyray]

Google says, a little key, tack rags and plastic primer. This true? Would adhesion aid help?

These are new smooth plastic parts btw.

Have some pics of much more funky paintjobs than what I'm attempting.

[composimmonite]

Have you thought of having them "wrapped" instead of painted ?

[steveo3002]

degrease it , key with a grey scotch pad and more degreaser

now look on the back , there will be a code like PP , EPDM or such , then go to the paint supplier and ask for a plastic primer suitable for what you have , that should do it

chances are that one above was done with no plastic primer , its not hard to do , and no you don't need a flex additive for the average modern plastics

[stonyray]

Nov 24, 2015 9:20:38 GMT composimmonite said:

Have you thought of having them "wrapped" instead of painted ?

I can barely apply tint to a flat headlamp never mind a bumper with curves and intricacies, I intend to paint the bumper myself to save ££££ and gain experience.

[stonyray]

it says PP-EPDM I will do precisely that.

[dodgerover]

Nov 24, 2015 9:27:52 GMT steveo3002 said:

, and no you don't need a flex additive for the average modern plastics

Do you mean the old type plasticiser? Is that the modern name for it, I wondered why the car paint shop had to go and get one of the old boys from the back when I asked about it a couple of weeks ago....

Just to state the obvious, when he says degrease, don't use the degreaser that you would on an engine, you need pre clean or something that doesn't leave a residue

[kevstarlet]

Ordinary panel wipe tends to leave the plastic sticky sometimes and very static, degreaser specifically for plastics can be got and doesn't cause the afore mentioned problems. I would always rub a new bumper with worn red scotch as to not cause any "hairiness" or use some new grey scotch. Most plastic primers are universal and I've never had any instances of paint flaking off.

[gazz81]

I used to use this.



Give the plastic a good clean then a coat of the u-pol stuff and than continue with primer and topcoat.

[steveo3002]

Nov 24, 2015 18:08:59 GMT dodgerover said:

Nov 24, 2015 9:27:52 GMT steveo3002 said:

, and no you don't need a flex additive for the average modern plastics

Do you mean the old type plasticiser? Is that the modern name for it, I wondered why the car paint shop had to go and get one of the old boys from the back when I asked about it a couple of weeks ago....

Just to state the obvious, when he says degrease, don't use the degreaser that you would on an engine, you need pre clean or something that doesn't leave a residue

yeah same thing , its only req for mega spongey stuff , if you remember the mk3 xr3 and some other fords you could pinch the spoliers like a sponge , that would need the additive

and yes panel wipe not gunk...and don't just wipe it over , use a clean wet rag and follow behind before it dries and wipe it off , repeat again with more clean rags

[kevralpina]

Red scotch brite soaked in celly thinners then acid 8 etch primer never let me down

[omega]

the best way to avoid that is



to buy my chrome bumper MGB.




sorted

[Rich]

Nov 24, 2015 19:33:42 GMT omega said:

the best way to avoid that is



to buy my chrome bumper MGB.




sorted

Useful insight as to how to solve the issue

[stonyray]

for degreasing i tend to use a clean rag and some brake cleaner,

I will then scotchbrite the whole thing with a grey (soft?) pad,

then I'm gonna give it a coat of adhesion aid cos you know it cant hurt matters

then plastic primer

then 800 wet n dry wet

the basecoat n laquer

sound good?

[stonyray]

Nov 24, 2015 19:33:42 GMT omega said:

the best way to avoid that is



to buy my chrome bumper MGB.




sorted

Yeah but then I'd have to start a whole new thread on how to paint over rust....

[kevstarlet]

There's no need to sand the plastic primer. Also most plastic primers are adhesion promoters so just a coat of plastic primer should do. Depending of the colour you're painting the bumper it may be advisable to hi build prime the bumper or wet on wet prime it. I.e. If the bumper was goin silver and you painted over the black plastic it would leave the bumper looking darker than the rest of the car.

[steveo3002]

some of the plastic primers will be like thinners no build or colour to it at all

so yeah if theres a need to smooth over some marks plastic primer it , then on with some high build and sand that trying no to go through too much

[stonyray]

The plastic primer I have is grey and apparently good for the kind of plastic my bumper is.

I think I will sand as tbh the bumper has some mold lines I would like to remove.

Also how long do I need to leave between colour and clearcoat (1K)??

EDIT: this will be used in a spray gun and not rattle cans

[steveo3002]

leave the colour coat long enough to flash over then straight on with the clear , needs to be like within the hour not next day

[stonyray]

Nov 25, 2015 15:07:14 GMT steveo3002 said:

leave the colour coat long enough to flash over then straight on with the clear , needs to be like within the hour not next day

Thanks for that, I was gonna wait 24 hours. so 30-40 mins is best?

[steveo3002]

in a warm room 10-15 mins should do it , you will it goes from soaking wet looking to a dull finish , its a common mistake people thinking you can leave it a day or more , the clear needs to go on fresh so that it sticks and doest peel off a few years down the road