How to improve paint adhesion on resin parts?

[dai phan]

Hi all,

 

Despite the fact that I wash the parts in soap and prime ( I use Mr Surfacer 1500), I found out the paint does not stick well to the resin parts. Any suggestions? Dai 

[Bob Beary]

Maybe clean with alcohol or Simple Green.

[airmechaja]

I have always primed resin parts with Tamiya primer and never had a problem with paint not sticking. 

[chukw]

Recently I was advised by customer service at Novus  (plastic polish) to use Mr. Clean to remove the silicone left by their #1 clean and polish (of the three-step set). It did the trick, and it just might for your resin.  Just let the parts soak for a while in a small container of the electric yellow liquid.

[RichB63]

3 hours ago, chukw said:

electric yellow liquid

!!

[chukw]

20 hours ago, RichB63 said:

!!

[RichB63]

1 hour ago, chukw said:

Thanks for the tip, it’s on my shopping list now. 👍

[sigtau]

On 5/1/2023 at 8:53 AM, dai phan said:

Hi all,

 

Despite the fact that I wash the parts in soap and prime ( I use Mr Surfacer 1500), I found out the paint does not stick well to the resin parts. Any suggestions? Dai 

Some resins seem to have terrible adhesion no matter how much cleaning you do.  Reskit in particular is very difficult to get Mr. Surfacer 1500 to stick to it.  The best solution I've found is to use heavily thinned Mr. Metal PE primer as a base coat.  It sticks to everything and can be applied very thin and still be effective.  It remains slightly tacky after drying.  Immediately coat it with 1500 once or your base paint color to prevent it from collecting dust.

[ElectroSoldier]

Scotchbrite and IPA.

 

I guess I should elaborate on that.

It sounds like you are suffering from what is called Amine blush.
You need to remove the hydrocarbons from the surface, especially if you have any open or flat surfaces where the lack of adhesion will be even worse.

So you need to remove it...
Its possible to use just water and some scotchbrite but I much prefer IPA on scale models because the areas that you cant get to with the scotchbrite will still need to be cleaned off and the IPA should do that just by contacting it.
Water not being equal all around the world (flouride, chlorine etc added to water supplies etc etc) then water isnt always good because it leaves its own problems behind.

As to the chemicals mentioned above, they are all American brands of which I have no clue, many of them may well work but it is the mechanical abrasion that is really required to remove the hydrocarbons.

Edited May 12, 2023 by ElectroSoldier

[Scott Smith]

I’ve used the “bleche white” tire cleaner.  Yes, it’s spelled that way.  Now lists it as “new formula” so I’d test it first.  
Funny, I googled this to get the spelling correct and an Amazon ad came up.  Clicked on it and it told me I last purchased this in 2018. 
 

But I actually soaked the parts in it overnight and rinsed off in hot water. 

[James B]

What type of soap are you using?  I had problems with paint adhesion until my wife pointed out I was using hand soap which has oils and lotions in it.  I switched to Dawn dish soap and have had no problems since.  Another clean with 91% Isopropyl Alcohol is a good idea.  Don't use 70% rubbing alcohol because that has oils for your skin as well.  Maybe a light sanding with fine steel wool or 800 grit paper will "rough up" the surface just enough to give some bite to the paint.

[Scott Smith]

If using soap only, Dawn dish soap.  Takes any and all oils off.  
Related story.  The windshield mirror won’t stay glued in place on my 1990 F-250.  Reading online it said to clean the glass and the part glued to it with Dawn dish soap and not alcohol, glass cleaner or acetone. They all leave deposits.  Dawn rinsed with clean hot water won’t.  
im going for the 5th attempt this week at gluing it back on.  Even the pros failed.