FUD FXD forming small crystals after time?

[Chris333]

So here goes. I soak FUD and FXD in Bestine and sometime use Acetone for short periods. My models get coated in high build primer. Then the surface lines get sanded out. Sometimes this is a many step process till I'm happy with it. Most black parts just get sprayed with flat black rattle can.

After time very small crystals appear on the surface. It looks like rainbow metal flakes in strong light. Right now this is the only photo I've been able to get:


That isn't dust on the model.

How do I fix this?

Just looked at Bryan's White Tower I built up about a year ago:
https://photos.app.goo.gl/HODWPFUibRtEFBR32
When I rotate it in the light I see specs of sparkles. I used Testors spray enamel of this with a few coats of Dullcote.

[Chris333]

Since taking photos of something reflective is hard, here is a quick video:

[peteski]

I have not seen anything like that, but I'm not as prolific FUD user as you are.  It is either something leaching through the paint or paint compatibility issue.  DO all your FUD items exhibit this problem or just some?  Anything in common with all those sparkly items?

[Chris333]

I've seen this years ago, but what started it now is this Porter model:



I hadn't been down in the basement this summer and when I went down there this Porter was crystallized. I built it about a year ago.

Some of my first Shapeways stuff did it over time:


Some stuff was soaked in Acetone and just sprayed flat black. Other parts were soaked in Bestine and primed/sanded/filed many times before painting. Some parts were scrubbed with Blech White and Goo gone.

[sirenwerks]

Ew. Have you asked Shapeways what the deal is?

[Lemosteam]

Since taking photos of something reflective is hard, here is a quick video:

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Nice truck! 

Bad FUD, BAD!

Damn that's weird.

I will look at my horse car roof. That's got six coats of tamiya TS6 on the outside with nothing on the inside.

[Mark5]

Some of my first Shapeways stuff did it over time:


Some stuff was soaked in Acetone and just sprayed flat black. Other parts were soaked in Bestine and primed/sanded/filed many times before painting. Some parts were scrubbed with Blech White and Goo gone.

Are the side panels on that hopper supposed to look like heavy cloth?

[Chris333]

Are the side panels on that hopper supposed to look like heavy cloth?

That's what you got at Shapeways 6-7 years ago.

[DKS]

https://www.shapeways.com/forum/t/powder-appearing-on-fud-after-storage.68722/

[thomasjmdavis]

Which brands/types of primer and paint are you using? 

I remember in the early days of FUD, several modelers reported having issues with the FUD not being fully "cured" (not sure if this is the correct scientific term) when they received it. They waited several weeks before painting.  Any chance that issue has raised its head again?

[Chris333]

https://www.shapeways.com/forum/t/powder-appearing-on-fud-after-storage.68722/

Sounds like they are talking about MEK solvents in paint and to use water based primers and paint. Still on page one though 

EDIT: jump to page 6 and they are talking about recalling their 3d printers because of this 

EDIT: EDIT:

oxygen exposure

[DKS]

Still on page one though 

It's worth it to make it through the whole thread. This is a known issue that has no definitive solution, unfortunately, but the discussion is occasionally eye-opening.

[Chris333]

Well at least I'm not the only one with this problem    (somehow that makes me feel good)


BTW these models are not ruined. I took a brush to dust off the Porter shown above to take photos. Brushing harder got rid of all the crystals. It is just one of those things that has always bugged me because it takes so long for the problem to show up.

[Chris333]

additional UV-exposure by the customer helps before using enamel paints

I did put my recent HOn30 PRR type speeder outside in the sun for a few hours before working on it. I still see crystals in all the nooks and crannies.

It was primed with Testors enamel:

And then sprayed with Tamyia acrylic:

[DKS]

My takeaway from the seven pages of at times turgid technospeak from semi-technopeople is that it may indeed be oxidation. Acrylic is known to oxidize (headlamp fogging, anyone?). Combine that with the variability of the acrylic formulas used, the possibility of "bad batches," all of the myriad post-production cleaning processes, etc., and who knows what might happen to the stuff.

I have a feeling this is what happens to early adopters of new technology that has not yet matured enough to discover all of the possible outcomes, especially those that occur over longer periods of time. This would not be the first time a new material or process was foiled by unforeseen effects down the road. But given the rapid growth of the market riding on the process, I suspect a solution will emerge.