FUD FXD forming small crystals after time?

[Chris333]

Yeah some people in that thread are talking about the rough powdery white areas as the same thing (the build lines).

Overall it seems that many different finishing methods get the exact same result.

As for oxidation. Shouldn't sealing stop that? Several coats of paint is a pretty good seal.

[arbomambo]

very sorry to see this happen to your very nice builds and paints...
 ...and now I see no future where I model with 3D printed forms...
~B

[peteski]

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?).

I thought that headlight lenses were made of polycarbonate. Acrylic is probably too brittle for such applications. I also was under the impression that the fogging/etching was a result of them literally being sandblasted by the dist/sand/small debris kicked up by the vehicles in front of yours.  I suppose that oxidation (of polycarbonate oxidizes) could be part of the fogging process too.

[up1950s]

Does this happen to Floquil or Scalecoat II ?

Geez just when we got over the oxidation with zamac , now we have to deal with it with paint .

Bestine trapped off gassing vs water based paint is my technoguess .

[Chris333]

I don't think the type/brand of paint/primer matters.

[Cajonpassfan]

Well sh!t, I shoulda used "Dawn", or baby shampoo....
Otto

[wazzou]

Well sh!t, I shoulda use "Dawn", or baby shampoo....
Otto

Looks like Head & Shoulders would be more appropriate.

[tehachapifan]

Relatively new technology....still a lot to be learned.

That said, many of the above models still look really good, IMHO, such as the HOn30 speeder.

[wcfn100]

Found a couple old cabooses I had printed and primed that had this sparkling effect.  I scrubbed it with a dry tooth brush and the effect went away.   

I'll look again in the morning to see if it's short lived.

Jason

[DKS]

I thought that headlight lenses were made of polycarbonate. Acrylic is probably too brittle for such applications...

Although polycarbonate is more common, they are made of either one. And while much of the fogging is due to the "sandblasting" effect, some of it is due to oxidation as well. Mine have fogged while the car has been sitting in the garage.

As for oxidation. Shouldn't sealing stop that? Several coats of paint is a pretty good seal.

I don't think you can create a 100% perfect seal without applying a lot of paint, since there will almost always be imperfections. Also, I suspect printed acrylic is likely semi-porous, so there will be trapped oxygen throughout the material--and my gut says this may be a significant aspect of the problem, and why the problem seems to vary between different printers: the quality of the printing may be key.

Bestine trapped off gassing vs water based paint is my technoguess .

The Bestine is long gone before you apply any coating. Heptane is the most volatile solvent made, and it will all be evaporated in minutes or even seconds. Water-based paints introduce their own problems, since water can contain dissolved oxygen.
 

[bbussey]

I've only had one painted ProJet resin model display the crystallizing like that, painted over 5 years ago, and it was one that I did not thoroughly remove the wax from. I have other painted models from that time using the same type paint and they are fine. I currently leave parts soaking in Bestine for at least 24 hours and usually more along the lines of 36 or 48 hours. I think it might be wax residue bleeding through. But as others have mentioned, it brushes off fairly easily. I haven't seen the crystallizing return on that model as of yet, and it certainly could return. But I have not seen the effect on any parts that have been thoroughly soaked in non-wax-saturated Bestine for over 24 hours.

[havingfuntoo]

I have had no experience with this stuff, but I am guessing that the materials are semipermeable membranes, like skin, plastic milk bottles and many other things. Also the material is layered causing microscopic layers for the volatile solvents to penetrate along plus being a membrane it will pass into it and migrate back out over a period of time.

After getting trapped under the paint it will force its way out, regardless whether the inside is painted or not, anything that has been dissolved by the gas will appear on the surface after the gas has gone.

Now this is only a theory, I have no experience I will say a second time, but I have had to deal with some castings that were powder coated after being recycled and there was a similar problem occurring. I know different materials. I wonder if you gave the items longer to breath before you paint them would the problem still happen.

Bestine contains Heptane or is Heptane? It is a solvent that quickly evaporates, but not when it is being retained in a piece of material that slows the products ability to evaporate.
Take a processed piece that you feel is ready for painting and place it in an air tight glass jar with a metal or glass lid (no plastic) and leave it in a warm (not hot) place for a about a week.  After this period of time cool the jar down in the fridge (not freezer) for a couple of hours and see if there is any condensation forming. If there is any take a piece of paper towel and collect it, then give it the sniff test, even if there is no condensation you can still use that sophisticated analytic tool (your sniffer) to asses the presence of any solvent in the jar when you first open it.

I will be interested in your findings if you choose to give it a go.   

[towl1996]

I've only had one painted ProJet resin model display the crystallizing like that, painted over 5 years ago, and it was one that I did not thoroughly remove the wax from. I have other painted models from that time using the same type paint and they are fine. I currently leave parts soaking in Bestine for at least 24 hours and usually more along the lines of 36 or 48 hours. I think it might be wax residue bleeding through. But as others have mentioned, it brushes off fairly easily. I haven't seen the crystallizing return on that model as of yet, and it certainly could return. But I have not seen the effect on any parts that have been thoroughly soaked in non-wax-saturated Bestine for over 24 hours.

My first shapeways model was in Jan of 2013 and I haven't seen any of this crystallizing, yet. Like Bryan, I've always soaked the models in Bestine only and for at least 24 hrs, sometimes for days, by accident. And the last couple of years I've done a two step soak, old stuff first, then some fresher stuff, it usually ends up being a couple of days of soaking. Lucky maybe, but so far so good.  And this won't stop me from getting @Lemosteam 's K4 kit. 

[bman]

I've only a couple different items (about 12 total pieces of product) from Shapeways over the past 3 years.  I pretty much soaked them for 24+ hours on 2 different occasions in Bestine, washed with unscented Dawn dish washing liquid, primed them with Forumla P3 black primer, then rattle canned them with Games Workshop Chaos Black.  I've not seen any of the symptoms as mentioned.  But like the last 2 posts, I soaked the parts in Bestine for longer time and more than once. 

But....  about 1/3 the way down on page 5 of that thread on Shapeways forum, someone chimed in who says they are part of the FUD-NY production team. (He is shown as a new member, later in the thread it is confirmed he is with Shapeways from some one from the CS Team) He mentions that this appears to be a material issue caused by UV degradation. And I quote, "Specifically, this degradation is caused by the photooxidation of free radicals (a byproduct of UV curing and UV exposure), which react with oxygen in the environment and break down the cross-links created during machine curing. This can explain why customers who left FUD parts in their plastic packaging did NOT experience the issue, from limited oxygen exposure in the bag." 

I wonder since I left my parts in their bag, in a dark drawer until prepping and painting if it helped prevent/delay this? Even though folks here are prepping their items well for painting, it will still happen if the process has started already I would think.  Kind of like painting over rust on metal probably.  And does leaving unpainted FUD items out in the open cause or accelerate this? As well as additional curing under UV lights?  Do certain cleaning products then react adversely to this as well?  It is strange that it appears to not happen across the board.  What is the reason it as to why it is or is not happening to everyone. 

[Lemosteam]

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

Please note that while there is much discussion, misunderstanding and fear in that thread, Shapeways has never officially confirmed or denied an issue, and certainly have never brought the "issue" to closure after nearly 11 months.

I have asked Shapeways specifically to comment.

I have many cleaned small detail parts that have been sitting a little parts bin, some since my first design was printed, and I will look at those and my painted Horse Car roof among other parts that have been cleaned and painted.

My cleaning process for six months has been straight bestine in an ultrasonic cleaner (under my watchful eye) for 20 minutes.  The parts come out of the fluid warm to the touch as is the fluid when I remove the parts.

At this point I do not recall seeing this development on any of my parts.

I think one misconception in that thread is some of the edge and corner artifacts that are hidden to the eye when the part is translucent, then are revealed after cleaning, and they have been mistaken for what Chris has shown.  I simply scrape those away during my finishing process as they are strange remnants that seem to scrape off as a powder, rather than a waxy substance or  hard, like something part of the base material.  An Air eraser works well too to remove these artifacts, which is why I built my little sealed sandblasting cabinet.

Unfortunately i do not have any uncleaned parts right now to photo document my process from beginning to end.  Please note that I am NOT trying to say that my process is the end-all-be-all or begin that debate.

@cbroughton67 , @Dave V  @chicken45 , (or anyone else) are there any signs of this on your PRR sheds?

@towl1996 , as always, thanks for your support.