Painting LLDPE plastic?

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Old 10-22-06, 08:59 AM
J
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Painting LLDPE plastic?

I've got a little project repainting some hand-me-down plastic toys from one of my sister-in-laws. Specifically a plastic play kitchen from Step2 and eventually one of those Little Tykes push cars.

The manufacturing process introduces hundreds of pores into the paint and when I spray the paint (Rustoleum for plastic and their general purpose spray) hundreds of pinholes appear in the paint and no amount of light coats of paint or even slopping it on will make them go away. That includes painting over dried paint.

I seem to need some kind of primer for plastics but I'd like to ask someone who has had experience painting this kind of plastic first. If anyone has dealt with this kind of plastic (which I wager is the same type in all of the blow-molded childrens' toys on the market) please let me know. I'll be out later today and will see if I can pick up some kind of general purpose primer and see if I get any farther with that.

It seems as though the poly-ethylene will take the paint but the surface imperfections are causing the paint to avoid the "pores" in the paint. I'm going to see if some light sanding will fix the bonding problem but I have a lot of area to cover. The can of Krylon Fusion my father had states that using laquer thinner or ammonia ought to help but if that doesn't work, I'd like input on what others have been using. I had seen a forum post "somewhere" years ago about someone who had painted a Little Tykes car with paint (I think it was Fusion) but I don't recall any problems they had in application of the paint or what steps they used when they prepped the surface.

Thanks a lot, hope someone can help me out!
 

Last edited by jcostantino; 10-22-06 at 09:32 AM.
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Old 10-22-06, 10:00 AM
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Ok, an update:

Sanding the surface allows the paint to adhere nicely BUT it also looks TERRIBLE due to the sandpaper just dragging around the plastic and not removing it. Using Goo Gone helps a little bit but in the end, it doesn't seem to be much better than just spraying on a clean, unprepped surface.

I found Bulldog Adhesion Promoter which claims to bond paint to anything and may give it a shot but it's about $10 a can plus shipping. I'm trying to keep the materials under half the cost of just buying new toys and if I get a couple cans of that plus the $15 in paint I already have, it'll be getting VERY close to not worth doing it before figuring in the cost of my labor.

Next step will be getting some kind of paint thinner and seeing if that melts the surface enough to remove/reduce the pores.
 
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Old 10-22-06, 05:41 PM
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Have you tried a primer designed for plastic? I don't know if it will fill like yu want but it should bond. You could also try an epoxy type product. you may want to head to your local paint store and see what they have in the way of industrial products
 
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Old 10-22-06, 07:20 PM
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That's my next step. I test painted it about 8 hours ago and it flakes off if I drag my nail across it.

Thanks for the info... I'm going to try to find something locally before I have to order it online.
 
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Old 10-23-06, 05:09 AM
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XIM makes a plastic bonding primer, it is the UMA line. I do not know if t will work on that type of plastic but it will be cheaper then an industrial product.
 
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Old 10-23-06, 06:48 AM
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Originally Posted by bclacquer
XIM makes a plastic bonding primer, it is the UMA line. I do not know if t will work on that type of plastic but it will be cheaper then an industrial product.
Their data sheet says it's not recommended for Polyethylene. Thanks for the suggestion though.

I saw a post on a forum somewhere about painting PE (specifically a Little Tykes push car that someone got second-hand) and I don't remember what the outcome of that was. If it's anything like what I'm experiencing, the paint should have flaked off readily unless the surface was scuffed to ugly.

In my research, I did come across someone who painted a PE gas tank (seems to be popular for dirt bikes in the 80's) and they coated it with fiberglass resin first. A project like that is beyond the scope of what I'm willing to do since this is just a $97 toy. Painting is just the first step, I would like to eventually replace the decals and I can see 4-5 hours just scanning the old ones for templates, finding suitable art for the new ones, and printing them.

I'm sure that the toy companies chose PE for its durability and UV resistance but it wouldn't surprise me if they also chose it because it seems to be completely unable to take most any kind of paint.

Hopefully there's some magical product that will let paint stick to the surface and I just haven't come across it yet. At the very least I could do the decals since the rest of the toy still looks decent.
 
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Old 10-23-06, 07:05 AM
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I'm going to try to "flame treat" the surface which seems to be the recommended way to go. Apparently the treatment oxidizes the surface layer and from what I have read, "allows adhesion from most types of paint." Which would be good.

The procedure is to pass a torch over the area quickly and evenly and if done right should dull the surface without melting it.

Unfortunately I only have a little torch cigarette lighter so I'll be working on a very small test area but if it works, I'll pony up $20 for a propane torch.

Would one of those weed killing torches work? I need one regardless and it would be nice to kill two birds with one stone.
 
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Old 10-23-06, 07:09 AM
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Originally Posted by jcostantino
Would one of those weed killing torches work? I need one regardless and it would be nice to kill two birds with one stone.
I don't know much about them but would think that they have too much flame for what you intend to do.
 
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