Post-Bestine Issue

[BCR751]

I recently received an item from Shapeways and right away put it in Bestine to soak.  I left it in for 6 days.  I removed it from the Bestine and went over it with a soft toothbrush and warm soapy water.  After it dried, most of the part had the normal white opaque look with the exception of one of the surfaces which was still translucent and sticky to the touch.  I put the part back into the Bestine figuring it needed a longer soak.  I left it in for another three days, took it out and washed it but the translucent surface still remained.  I used a Q-Tip dipped in Bestine and scrubbed the surface but to no avail.  It is still translucent and sticky.

I've not had this happen to any other 3D printed parts.  I'm thinking this surface is not going to hold paint.  Has anyone experienced this issue and, if so, is it correctable or do I need to have it re-printed?

Doug

[chicken45]

Oh yes. This has happened to me.
 Details to follow while I dig it up...

[chicken45]

@BCR751
Here you go!

https://www.therailwire.net/forum/index.php?topic=39069.0

[C855B]

The problem is insufficient time in the UV curing oven, which I think may be because SW may have batched too many pieces and your uncured surface was shadowed. Some folks have had success leaving it out in the sun for a couple of days. I've been able to get some reduction of the uncured areas (albeit under cured surfaces) with the sunlight trick.

Failing that, it's reprint time. The UV levels required for curing are very high and aren't something you can get in the bulbs department at Home Depot or whatever.

[lashedup]

The problem is insufficient time in the UV curing oven, which I think may be because SW may have batched too many pieces and your uncured surface was shadowed. Some folks have had success leaving it out in the sun for a couple of days. I've been able to get some reduction of the uncured areas (albeit under cured surfaces) with the sunlight trick.

Failing that, it's reprint time. The UV levels required for curing are very high and aren't something you can get in the bulbs department at Home Depot or whatever.

Really depends on the resin being used. The printer I have at home uses 405nm UV LED wavelength and that's fairly common for nail salon curing devices. That said, the sun covers most of the wavelengths necessary to cure things (some laser resins are trickier). Just be careful not to over cure as it makes some resins brittle. Painting them after curing usually prevents any more curing issues (cracking, shrinking, etc., etc.).

Still scratching my head on bestine (and the frosted resin shape ways uses for fine detail). Most every other manufacturer of SLA 3D printers (Formlabs, Wanhao D7, etc., etc.) use rubbing alcohol to clean off extra resin before curing. There are new resin cleanup products just hitting that are even better and won't cloud the print like IPA does/can.

- jamie

[Lemosteam]

The bestine is simply used to melt away the wax support residue from the printed part, that's all. 

If the translucent area is sticky it is uncured.  Take a pic and file a complaint using their email form to attach the pic and ask for a reprint. 

If the translucent area is not sticky, it is cured SOLID all the way through where you are looking.  No amount of bestine will make it opaque and it will paint up just fine.

Opaque is not necessarily the absence of wax so that alone should not be used to judge if a part has been fully cleaned of wax.

@lashedup , FUD sand FED are not printed like SLA printed materials, i.e. the liquid SLA uses.  Those materials are printed, cured and cleaned differently.

[BCR751]

Well, this surface is definitely sticky so I guess I'll take a photo, send it to SW and ask for a reprint.  If it isn't properly cured, no amount of scrubbing is going to make it right.  BALLS!

Oh, and thanks @chicken45 for the information.  Much appreciated.  Need to dust off the ol' trombone.  Community band season is about to start 

Doug

[peteski]

Still scratching my head on bestine (and the frosted resin shape ways uses for fine detail). Most every other manufacturer of SLA 3D printers (Formlabs, Wanhao D7, etc., etc.) use rubbing alcohol to clean off extra resin before curing. There are new resin cleanup products just hitting that are even better and won't cloud the print like IPA does/can.

- jamie

I don't believe that Shapeways ever recommended removing the wax residue using Heptane (Bestine is a brand name).  I believe that this was simply something that some modeler used successful and the word just spread throughout the modeling community.  IIRC, Shapeways recommends a rinse in olive oil, followed by warm water and  dishwashing detergent to remove the oil.

This is done not to rinse off uncured resin but to remove the wax which was printed as a support structure for protruding parts of the printout.  Like John mentioned, this is is a different printing process than the one you use.

[Chris333]

Try  setting it out in direct sunlight for a while.

[lashedup]

@lashedup , FUD sand FED are not printed like SLA printed materials, i.e. the liquid SLA uses.  Those materials are printed, cured and cleaned differently.

Interesting. Makes me wonder why that's their choice for finest detail. There are far better choices.

[bbussey]

It’s uncured resin. Report it to Shapeways with a photo and they will reprint the part.

[chicken45]

I forgot to mention that I actually put it in the sun for a few days. The HOT Baltimore sun.
It didn't do anything.

Has anyone done this successfully instead of in theory?
Just curious.

[C855B]

Partially, but not on an uncured surface. I had a couple of shells with obvious uncured resin beneath the surface, and was able to get some reduction of the uncured area.

[BCR751]

Well, I sent Shapeways a note with a photo of the affected part asking for a reprint and this is their reply:

"We highly discourage using Bestine on Fine Detail Plastic material. Bestine is a chemical that actually disolves the material, the longer you soak it, the more sticky and soft the Fine Detail Plastic gets since it's disolving.
Models are cured during the printing process already but are cleaned with oil, this could cause the model to feel like its uncured.

I recommend using soap to clean the model or bestine for not longer than a minute to dry out the material."

So, I guess I'm S.O.L. for getting a reprinted part and maybe we should all re-think the Bestine soak.  I think @peteski get it right in his reply.

Doug

[chicken45]

Well, I sent Shapeways a note with a photo of the affected part asking for a reprint and this is their reply:

"We highly discourage using Bestine on Fine Detail Plastic material. Bestine is a chemical that actually disolves the material, the longer you soak it, the more sticky and soft the Fine Detail Plastic gets since it's disolving.
Models are cured during the printing process already but are cleaned with oil, this could cause the model to feel like its uncured.

I recommend using soap to clean the model or bestine for not longer than a minute to dry out the material."

So, I guess I'm S.O.L. for getting a reprinted part and maybe we should all re-think the Bestine soak.  I think @peteski get it right in his reply.

Doug

I can say with 100% confidence your parts were sticky before you soaked them.
Mine sure were.