FUD FXD forming small crystals after time?

[Chris333]

[Chris333]

OK got my HF cleaner, corn oil, and baggies. Plus a Shapeways order in the mail.

I used to dislike Harbor Freight then they opened one 1/2 mile from me. I have bought so much stuff there since. Mostly for working on my car. But yeah they know me by name now

[Chris333]

So I filled the tub with water. Filled a biggie with corn oil. Put some parts in there and let them go through the max time cycle 3 times. Pulled the parts out and the looked like clear glass. Rinsed them off and added Dawn dish soap to the heated water in the tub. Soaked the parts in that for one max time cycle. Parts are now a little cloudy. Letting them air dry now.

With the cleaner had a timer on the heater. It would be real easy to leave and come back several days later to see the heater is still on 

[wazzou]

I must have missed the Corn Oil phenomena.  Is that in lieu of Bestene or what is the theory behind its use?

[Lemosteam]

Some  details from 3DS on FUD (SR200)... including post processing and finishing recommendation  ... can be found on page 28-32 of the following.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwiq_LbxjaTXAhXl64MKHXp6DZEQFgg6MAM&url=http%3A%2F%2Finfocenter.3dsystems.com%2Fproduct-library%2Fsystem%2Ffiles%2Flegacy%2F3DSCentral%2520-%2520Legacy%2520Products%2FProJet%25203500%2520Series%2FCustomer%2FPost-Processing%2520the%2520Parts%2F2107_VisiJet%2520Material%2520and%2520Post%2520Processing%2520Guide.pdf&usg=AOvVaw18AKCPTN2PPUYEDYYyb0ge

@wazzou , see above link...

[Chris333]

From the instruction of the machine they use:

Supports are removed by placing the model in a controlled-heat environment that quickly melts the wax support material but with a temperature
not so high as to adversely affect the model itself.
The use of solvents to remove all residual support material is not necessary, and not recommended, unless further finishing, for example painting,
is required.
The recommended temperature for melting support wax from most parts is 60°C (140°F). Using a higher temperature will accelerate melting, but
caution is required to prevent part warping.
The process for support removal consists of two basic steps. The next step in 0.5.2.1 Removing Bulk Support Material, describes how to remove
the bulk support material and in 0.5.2.2 Removing Residual Support Material, describes how to remove the residual material. This process may
need to be scaled up to accommodate larger parts built on the ProJet 5000 system.

Ultrasonic Cleaning
Users cleaning parts with trapped cavities and other internal geometries or moving parts may require a more thorough cleaning method. This
method involves placing parts in a heated ultrasonic cleaner filled with corn oil. It is recommended to select an ultrasonic cleaner with digital heat
and temperature control. Jewelsmall is an online company that sells industrial ultrasonic cleaners. 3D Systems recommends the SH150-4L model
for the majority of parts built on the ProJet. A larger cleaner may be required if larger parts are the norm.
The corn oil or another similiar oil acts as a mild solvent that will penetrate internal areas where residual wax may pool and remove it while
keeping the wax slightly above the melting point. Peanut oil, canola oil and light mineral oil may also be used.
Follow these steps:
Fill the ultrasonic cleaner with corn oil. Set the
temperature to approximately 55°C (131°F). During the
first fill it is recommended to run the ultrasonic action for
30-45 minutes to accelerate heating.

Place parts into corn oil bath and set ultrasonic cleaning
cycle for 5-15 minutes depending on part size and
quantity. Avoid cleaning for more than 30 minutes. The
ultrasonic cleaning will shut off automatically when the
cycle is complete.
Corn oil bath should be changed out when oil becomes
cloudy in appearance or parts still come out with a waxy
feel.
NOTE: The ultrasonic action will generate additional
heat energy even after the heater control is set. This
can cause spikes in heating and distortion of parts if
they are left in the ultrasonic cleaner for long periods
of time.

Remove parts from corn oil bath shaking off excess and
place into heated crock pot of soapy water. Water should
be kept warm, not scalding with dishwashing liquid to
create a soapy bath. Dawn dish detergent is preferred as it
has an anti-grease agent. Agitate parts in bath by hand for
several seconds until oil is removed.
Use low pressure compressed air to aid in blowing excess
oil from the surface of the part.
Final Rinse and dry
Running Water Method - Place parts under warm running
water for several seconds as a final rinse. Use an
absorbent towel to dry parts.
Use low pressure compressed air to aid in blowing excess
liquid from the surface of the part.
Final Part Inspection
Inspect part carefully for any remaining wax or oil. Use an
absorbent towel to wipe the surface completely dry. Use a
cotton tipped applicator to carefully remove any small
amounts of oil that may have pooled in crevices.

SPECIAL CONSIDERATIONS FOR PARTS BUILT WITH VISIJET EX200:
Because of the higher transparency of the EX200 material, parts must be cooled slowly to prevent internal crystallization which has the
appearance of a spongy, crystalline structure along the surface of the part.

Sanding
If desired the model can be hand sanded to remove layer lines and improve the surface finish for further processing. Dry sanding of the model is
not recommended. Wet sanding with light application of water or oil prevents scratching and minimizes sanding dust. Sand with progressively
finer grits of sandpaper - starting at 320 grit and progressing up to 2000 grit to achieve desired finish. Apply more water or oil frequently to keep
the part wet.
Painting
It is highly recommended to use a primer on any ProJet parts prior to painting. Any lacquer-based automotive primer will perform well. A low cost
option is to use RUST-OLEUM Automobile Primer (gray finish) in a spray can. The RUST-OLEUM Automobile Enamel is an effective topcoat.
Follow the application instructions on the can to prime and paint parts. Touch painting can also be done using a water based acrylic paint. For
large volume painting or painting very large parts a paint sprayer or airbrush within a paint booth. The size of the paint booth should be
determined by the size and volume of parts that need to be painted.
Any lacquer-based automotive primer should prove satisfactory. Specifically in the US, "Specialty Plastic Primer" from RUST-OLEUM and the
interior oil-base "Sealer-Primer Stainblocker" from KILZ have been used successfully. Both are white-pigmented primers that can be coated with
almost any all-purpose spray paint, such as "Painter's Touch" from RUST-OLEUM.
The models also accept a water-based acrylic paint. Apply paint by using an airbrush techniques.

[chicken45]

I had a shapeways order of 6 or so tool sheds and many of them were messed up. They were actually sticky. It was like they didn't cure. After the soak in heptane, and an air dry, these sticky spots were still clear instead of the frosted white.
Setting them in the sun to let it have some UV didn't help. I emailed Shapeways and they actually said to soak in olive oil. In this case, I did nothing for me.

[havingfuntoo]

Did they specify the type of olive oil to use?

If you used virgin olive oil or first cold press olive oil they contain a high content of olaic acid, and that might be what is required to stabilize the item. If you used light olive oil you are using oil that has been extracted with solvents and centrifuged out of the pressings that remain after the first or second pressing. Light olive oil usually contains a low amount of solvent that has not been removed in the manufacturing process and low levels of olaic acid, it really is rubbish, but in this fat content conscious world it has found acceptance with a certain demographic. 

[thomasjmdavis]

Some  details from 3DS on FUD (SR200)... including post processing and finishing recommendation  ... can be found on page 28-32 of the following.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwiq_LbxjaTXAhXl64MKHXp6DZEQFgg6MAM&url=http%3A%2F%2Finfocenter.3dsystems.com%2Fproduct-library%2Fsystem%2Ffiles%2Flegacy%2F3DSCentral%2520-%2520Legacy%2520Products%2FProJet%25203500%2520Series%2FCustomer%2FPost-Processing%2520the%2520Parts%2F2107_VisiJet%2520Material%2520and%2520Post%2520Processing%2520Guide.pdf&usg=AOvVaw18AKCPTN2PPUYEDYYyb0ge

THANKS! for posting that.  Now, as to why it is that shapeways doesn't include those instructions with every part they ship (at least the parts they shipped to me) I can't say. 

[Lemosteam]

I had a shapeways order of 6 or so tool sheds and many of them were messed up. They were actually sticky. It was like they didn't cure. After the soak in heptane, and an air dry, these sticky spots were still clear instead of the frosted white.
Setting them in the sun to let it have some UV didn't help. I emailed Shapeways and they actually said to soak in olive oil. In this case, I did nothing for me.

If I remember they were fused together during a sloppy post print curing process.  Essentially they became one part, and that is why the oil did not work.

[Lemosteam]

From the instruction of the machine they use:

That is one seriously detailed, time consuming and potentially messy process. 

I suspect that @SandyEggoJake is correct about the wax absorption when they mention "cloudy" oil as an indicator for when to replace the corn oil in the vat.

"Corn oil bath should be changed out when oil becomes
cloudy in appearance or parts still come out with a waxy
feel."

[chicken45]

Did they specify the type of olive oil to use?

If you used virgin olive oil or first cold press olive oil they contain a high content of olaic acid, and that might be what is required to stabilize the item. If you used light olive oil you are using oil that has been extracted with solvents and centrifuged out of the pressings that remain after the first or second pressing. Light olive oil usually contains a low amount of solvent that has not been removed in the manufacturing process and low levels of olaic acid, it really is rubbish, but in this fat content conscious world it has found acceptance with a certain demographic.

1. I'm stoked you know all that. I think "light"stuff is horrible. Maybe instead of removing the fat from my sour cream and adding 5412 more ingredients I cannot pronounce, I'll just eat it less often.
2. I actually wrote them back to get verification. They responded to me "like you use to cook meat." Personally, I don't use the good stuff for that. I use the good stuff for salads and the sipping of bread. But they did not specify first press or anything further than cooking meat.

If I remember they were fused together during a sloppy post print curing process.  Essentially they became one part, and that is why the oil did not work.

3. John, yes, some parts were stuck together...those were the frames, but I still had sticky spots on the main sheds. I actually emailed them specifically about the sticky spots on these. I knew olive oil would not separate the fused frames.

I do find it strange how after a bestine soak that there are still clear spots while the rest is white. I don't understand what is different to make that happen.

[Lemosteam]

@chicken45 , I have responded to this many times.

If and I mean if, the printing process completely cures (due to photo hardening from the laser) the outer section both to itself and the previous layer and the hatching inside the section like the pick @peteski shows above, those areas become completely solidified and almost non-porous, so what you are seeing is the material in is hardened form, which is essentially a transparent version of the material.

Another way that can happen is if the fluid gets trapped uncured inside the section during the printing process and stays fluid, until UV curing.

[SandyEggoJake]

THANKS! for posting that.  Now, as to why it is that shapeways doesn't include those instructions with every part they ship (at least the parts they shipped to me) I can't say.

Your welcome @thomasjmdavis

I suspect the reason SW doesn't recommend end users try this is as a process is it's the post production process THEY use (as recommended by 3DS) to clean parts before they send to us.  So the parts have already undergone an oven > corn oil > dish soap process.  And the vast majority of the support wax has already been stripped ... but obviously some often remains.  For many purposes, this wax isn't an issue. 

Note 3DS does say "The use of solvents to remove all residual support material is not necessary, and not recommended, unless further finishing, for example painting,
is required.  So as we are obviously painting, issue is finding a suitable solvent for the desired effect. 

So if the issue on a part really is support wax, another round of corn oil and dish soap should be adequate. 

If one is seeing truly sticky parts like @chicken45, then suspect the issue is uncured resin... and a longer UV exposure may fix  ... but the issue also might be a void of liquid resin deeper in structure where UV or the required spectrum might no longer be able to penetrate or a batch of resin deficient in photoinitiators .  If you get parts so sticky that they stick together (something I've yet to see) I'd send them back to SW and have them make it right.   (I wouldn't go too crazy with UV light boxes as some SWers do... as such is just speeding up the degradation of FUD, causing it to get more yellow and brittle.) 

With these two issues out of the way, we are then left with what to do for paint prep that best avoids the iridescent crystals and breakdown of FUD.  For this, I don't have an answer yet.

@peteski is of course right above that a (brief) rinse in n-heptane (e.g., Bestine) doesn't  etch (much) the translucent areas of FUD. 

Again, polymer chemistry isn't my area of expertise, but so far I have two general working hypothesis: The crystals arise from reactions related to either TEG-DMA or the urethane compounds in FUD.  In fact I'm starting to favor urethane.    Mostly as urethanes are colorless plate shaped crystals, and a note by a SW employee stated these crystals seem to be more pronounced on regions formerly touching the wax support.

Recall when the wax is removed, it exposes the white frosted region, which is the primordial lattice of urethane.  As the build progresses, both more urethanes and TEG-DMA is incorporated.  The translucent areas have a higher level of TEG-DMA related compounds on the surface combined with a different crystal orientation.  Harsh solvents like MEK and Acetone will remove wax as well as etch (and eventually destroy) both urethane and TEG-DMA bonds.  While a brief rinse in hepatane also removes wax and seems to have less of an etch effect on the lattice, but it remains unclear to me still is if it's not impacting TEG-DMA and/or urethane in someway ... leading to the iridescent crystals appearing under certain conditions. 

Anyway, please understand this is still highly speculative on my part, but I will try to get more details and report back.



 

[orionfield]

This is the reason I dropped shapeways and found a local alternative. Now I don't need to worry about shipping, my printing costs are lower; and because my vendor uses higher quality machines, my customers don't need to worry about anything other than some light sanding of their parts. No cleaning required.