FUD FXD forming small crystals after time?

[Chris333]

I tired it on a bottle of craft store paint. It was brand new and the top was watery. There was no free space in the bottle so shaking didn't do much. The cleaner mixed it, but yeah the paper label got wet... oh well.

[nscaleSPF2]

Verne has been thinking hard about this crystal issue.  So hard that I have to poke him every so often to wake him up.  He wants me to pass on his observations.  I don’t know if this is going to help anyone, but here goes.

The surface of the PRR Position Light Signals that we printed from FUD appeared to be porous.  He used a brush to paint them (he’s no Leonardo with a brush, but he’s not that bad, either) because was too lazy to mask off the LED’s.  The first coat seemed to soak into the FUD; the second coat was more even.  Conclusion:  since the tiny molecules of plastic are not porous themselves, then the paint must be flowing into the space between the molecules.  You can kind of see this in the photo, which was taken after the first coat of paint.

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Of course this doesn’t prove anything, but it may indicate something.

Verne uses a different technique to wash the parts.  Since he is too cheap to buy an ultrasonic cleaner, he soaks the parts in Bestine for only about 10 minutes.  Then he washes them with a soft toothbrush loaded first with Bestine and then with the toothbrush soaked in dilute dish soap, followed with a warm water rinse.  The parts are allowed to air dry.  (The missus is no way going to allow Verne to get close to her oven with some tiny plastic parts.  No way, not since the last time.  But that’s another story.)

So the bottom line is that Verne thinks that he has cleaned off the surface of the FUD without allowing the supporting wax to penetrate the “pores” during an extended soak in Bestine and by using an ultrasonic cleaner.  That’s his story and he’s sticking to it.  At least we haven’t seen any crystals form on the surface of the position light signals.

[narrowminded]

I suspect you could be on to something there.  The problem is very possibly something like that but it sure would be nice to know so that a logical next step, repeatable solutions, could be pursued.   

I wonder if it would help to submerge a part in a primer and pull a vacuum on it, pulling and releasing a few times and therefore drawing paint into those voids.   Might even help the strength.  

And while we know that would help, does the paint know it and did it tell the FUD?

[Lemosteam]

1- We kow the material is Pourous
2- We know SW Bakes the part to remove the majority of the printing wax
3- it is easy to surmise the much of the wax is drawing into the pores in its liquid state during the melting process
4- We know the part is still covered in the wax when received, due to its translucent state
5- We have observed that when the part is relatively clean (I use relatively because we still have not determined HOW clean) due to the part not being translucent anymore.

Only something that dissolves wax can likely remove it from those pores and the agitation/brushing help to get it out?

[DKS]

Only something that dissolves wax can likely remove it from those pores and the agitation/brushing help to get it out?

That's why Bestine is the solvent of choice for many; it is known to effectively dissolve wax. The degree of success is likely a function of time and agitation. The difficulty lies in being able to determine the amount of wax, if any, that remains. Even after 9 pages of speculation and analysis, I'm still left wondering if the powder is some crystalline form of the wax leeching to the surface.
 

[Scottl]

This all reminds me of a challenge I used to deal with reguarly.  We had to chemically dehydrate sediment samples using acetone to avoid having residual water that would impair the subsequent epoxy resin.  You would soak the samples in acetone and replace it every day or so, increasing the soak time progressively to about a week for the 10th iteration.  We could measure the water with specific gravity and it is an asymptotic dilution of the water by acetone replacement. We reached a steady c. 1% water content after about 10 replacements (and about six weeks...).  There was no mechanical assistance and the material was fine-grained sediment that has low permeability (but high porosity).  I wonder what the porosity of the SW prints is?  The infiltration of the Bestine may be incomplete.

So this is a long way of saying that the Bestine works, but the problem may be that there is dissolved wax in the Bestine that remains in the pores and on the surface after it is removed and residual solvent evaporates.  I wonder if to remove the wax (more) fully, several applications of clean Bestine are needed?  It goes without saying that re-using Bestine would presumably increase the background residual wax content.

[Chris333]

Anyone put Bestine in their ultrasonic cleaner?  I'm guessing don't use the heat 

[Lemosteam]

Anyone put Bestine in their ultrasonic cleaner?  I'm guessing don't use the heat 

I do all the time (never, ever  unwatched) and it warms up on its own- my UC is not heated.

[nscaleSPF2]

That's why Bestine is the solvent of choice for many; it is known to effectively dissolve wax. The degree of success is likely a function of time and agitation. The difficulty lies in being able to determine the amount of wax, if any, that remains. Even after 9 pages of speculation and analysis, I'm still left wondering if the powder is some crystalline form of the wax leeching to the surface.
 

All of my contacts with Shapeways have revealed that the “technicians” in New York are clueless when it comes to this type of issue.  The real scientists live elsewhere, perhaps in the European office.  My next project will involve a source other than Shapeways.   

[Cajonpassfan]

I've never been 100% sold on Bestine, and although I've used it on a number of models, I'm looking for alternatives. My most recent Shapeways print is apparently in the mail, and its designer, who lives in Italy, recommends using a caustic soda wash and scrub. Has anyone here tried caustic soda to clean FUD/FXD parts?
Otto K.

[mighalpern]

be very careful with caustic soda, we use it at our plant
 serious burning to the skin and your eyes i.e blindness if you get it in. 
goggles and double up on the gloves at minimum.
 have lots of water to rinse.   just watch it if you a scrubbing with a brush too.  The spray residual on the counters and such are still dangerous

[peteski]

Sodium Hydroxide (aka, Lye or Caustic Soda) is the main ingredient of several plastic-safe paint strippers used by hobbyists.  Things like Easy-Off Oven Cleaner (the original, not the new low-fume formula), Castrol Super Clean degreaser (or Purple Power which is a generic version), and few other stripping solutions offered for sale from time to time.

I have no ideal how it will affect the FUD wax but like mighalpern said, be very careful when using it. After all Lye is often shown as a chemical that will dissolve corpses of murder victims in crime dramas.    It is a very caustic chemical and extreme caution is required when dealing with it. It will burn your skin and eyes.  It also can damage other things (like aluminum).

I think that until the composition of those crystals is analyzed we are coming up with alternate solutions without understanding this specific problem.

EDIT: Silly spelling misteaks

[Cajonpassfan]

Thank you for the warnings guys, much appreciated. When i was young, I didn't pay much attention to such warnings, but now I do. Perhaps the Italian stuff, like their humor, is less caustic?
The most recent off-Railwire but credible advice I'm getting is to use warm, polyunsaturated corn oil followed up by warm water and dish detergent, making sure I let the porous print dry out over several days. Anyone here tried that approach?
Otto K., scratching my head...

[Sokramiketes]

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.

I'm with Bryan on this one.  It's leftover wax.  I have a very early T-gauge E8 shell, before we were stripping the wax off with anything, that was painted with Pollyscale black.  The model was almost completely white last time I had it out.  The residue feels like wax.  It migrated through the paint layer. 

I haven't noticed it in anything that has been thoroughly cleaned, Naptha in my case.

[Lemosteam]

This is my experience as well, especially after cleaning the parts in the UC and Bestine.