Serious painting problems with polished WSF

One of my customers has purchased a polished WSF model, and sprayed it with Tamiya primer, followed by Tamiya gloss paint.

Five days later, the model began to smell pungently, and a greasy film appeared on the model. The gloss finish became discoloured, and a white residue seeped from it. The smell by all accounts is obnoxious, and spread through the whole house.

Has anyone had similar issues, and has anyone any thoughts on this? Many thanks.

Just bumping this topic to see if there's any response. Has anyone else had painting problems with polished WSF? Many thanks.

I have not attempted to use spray primer and paint on polished WSF. My paint-on primer and acrylic paint has given me no issues. If the customer has images, that might help with diagnosis. I believe the polishing is done in a soapy tub with the polishing media, so maybe some of the soap remained in the model?

Another polished WSF model, brush finished with Humbrol enamel. While much of the paint covered reasonably well, all along the base of the roofline the paint bubbled and smudged, leaving an unsightly, tacky mess. This is a huge disappointment, as if these models cannot be painted, they are worthless.

Closeup view of a WSFp model painted with Vallejo acrylic colors.
I did it without a priming. Instead, I sealed the model with a coat of clear varnish before I painted it.
No problems so far.

I just received my latest order with WSFp test prints, and I'll paint them the same way.

I do not wish to be critical, but perhaps you will permit me to make a few observations and ask a few questions:

1. I would ask if the object was painted with a coat of sealant first. I have found that since WSF is porous, sealant improves the painting process.

2. I do not know the scale of the object in question. Nevertheless, it appears to me that the paint on the bus is somewhat thick in places. Another thing I have re-learned (I had been told this before) is that thin coats are much much better than thick coats. It takes longer to complete painting overall, but the time wasted due to errors is much smaller. Thin coats of paint also help to preserve the texture of the print, which I find aesthetic.

One final question: Did you apply multiple coats of paint? If so, did you wait a sufficient amount of time between coats? A coat of paint that has not dried completely can damage the appearance of the subsequent coat of paint. See http://www.humbrol.com/hints-and-tips/painting-and-varnishin g/basic-humbrol-tips/

Below pictures of another 1:76 scale bus model in polished WSF. This was sprayed with Tamiya primer, followed by Tamiya gloss. After five days, a stinking residue formed on the surface, eating and destroying the gloss finish, and smelling up the whole house.

There is no warning anywhere on the Shapeways site that painting these models might result in a stinking, oozing mess that renders the model fit only for immediate disposal. I made these models available to this customer in good faith. I had no idea that this material was so pungent or dangerous, it looks just like regular plastic. I would urge Shapeways to let us know straight away what the health risks involved are, as I now have a very, very angry customer, and I have no answer for him. As a result, I have withdrawn my models, and it looks like I may have to abandon the Shapeways project.

What if somebody's child somewhere ingested this poison from a model I made available, regardless of what kind of sealant or preparation I might recommend to the buyer? How do I know what kind of paint a buyer is going to use, or how unsuitable? Is it my responsibility to put a health warning on them? I have to be honest, this unexpected result frightens the life out of me. I had no idea the material was so volatile, I assumed it was simply plastic like any other plastic I have modelled with. I would love a definitive statement from Shapeways on this. I will assume nothing any more.

If you want it all in one color, I suggest using dye. I have had no problems dying polished WSF. See the photo of some puzzle pieces.

Have you tried felt-tipped markers?

It seems that the problem is enamels, or the combination of them with the polishing. WSF with acrylics or CA glue works fine, and someone had posted images of his buildings in WSFP, painted with acrylics too. Have you tried enamels over plain WSF, not polished? If that works, then it has to be the enamels+polishing.

It could be soap or water left overs from the process, that react with the enamel coats. Extra washing and drying should help, but best is probably to cover with something that resists enamels and can dry with water involved, as WSF will keep some moisture inside. Tamiya primer is not acrylic, and their normal "acrylic" paints are not like others, so beware too. Go with artists or model acrylics instead, the type that works with water and have no alcohol.

Sorry, no enamels arround, you will have to buy a small bottle of acrylic varnish, paint or medium (Vallejo's 2 pounds or less) or CA glue, and see if enamel will still react or the acrylic/CA is a good enough barrier. Anyway, clean the models with lots of water first and let them dry.

as a general rule of thumb i recommend never painting soft plastics with enamals.... bad things always seem to happen.

when in doubt use acrylics.

With my first WSF model, after talking to a few people in art shops and reading posts on this forum and wiki, I painted using acrylics.
I did several layers and finished with a few coats of spray-on-gloss.

Turned out really well, little details and all, youve just got to be a bit mindful of WSF absorbing the paint a bit but its no real issue.

I haven't got any photos I can put up other than those I orgininally took, but I've painted PWSF with enamel paint before and it hasn't resulted in what you are describing (the bubbling and smell).

I didn't prime anything and I only painted maybe 40-50% of the model in enamel (humbrol) and left the rest of the model with the white plastic showing through.

Maybe it's a combination of the primer you;re using and the enamel. I can't say anything about acrylic though as I've never used it.

Wow. That really is quite the mess. There must be something in the Tamiya primers or the enamels that could be reacting with the nylon (WSF) material.

I used water based Testors acrylics, with no primers or clear coats several months ago on my Earthworm Jim figure and he is holding just as good as day 1. No smells or dripping (or melting, because that what your models sounds like it's doing). He did require several layers for his base color though, as the WSF material is extremely absorbant. All the layers dried within minutes.

For my most recent model I've ordered some VHT Prime Coat as a filler/primer and Alclad II Klear Kote. I'll post my results on this combination when the project is finished.

This thread actually has me really worried about certain primers and clear coats now. I was considering Tamiya paints before my print arrived because it's so affordable on ebay.

But really, the models can be painted. You may have to put warnings with items sent to your customers on what types of paints/primers/clear coats are safe.

I painted a model of a crane I made a few months back using various Testor enamel paints. Some parts were polished WSF some were regular WSF. I put 2 coats of paint on without primer and haven't seen any changes with the prints.

Are we aware that somebody resurrected a two years old thread here ?
Could have been a bad batch of paint for all we know.

Yes, I noticed the date after posting. But it didn't seem to have any answers yet so the extra info couldn't hurt if anyone else runs into this issue.