Glowing under UV light.
Once in a while you set out to hunt for a special goal. Mine was to print something with clear resin. The model should be used a a stand for miniatures. It should be printed in 50xy/50z.
As the original this is a story in eight fits.
1. Looking for a clear resin, who do you gonna call ?
Ghostbusters would be the wrong answer. Anyway there are not many clear resins to be used directly for printing. Most are only meant as base for your own mix.
There are two notable exceptions. Venus Creators Clear Resin and formlabs Clear Resin.
Venus Creator claims it's designed to be used with the B9Creator. So I ordered a bottle from a German Company.
There was nothing indicating that the resin would not be shipped from Germany, so I was rather surprised, when I got a notice from the customs office.
2. The resin proofed to be usable without too much hassle. The test print mode of my software proofed to be a time saver.
But the print has a strong yellow cast. First I thought I might have contaminated the resin, but in the meantime I read a review with the same finding. To call this water clear you must live at the yellow river. It's the center model in the image.
3. So I ordered a bottle formlabs clear from formlabs' European Store. This time the resin was really shipped from within Europe, and it was delivered quite quickly taking into consideration that it shipped from the UK.
The stuff is so viskose you might mix it with honey to make flow faster. A pain in the vat to work with.
4. I couldn't find an exposure setting to work at 50xy/50z. The exposure times were very low, and it would undercure (read doesn't form correctly) or overcure (read bleed), but never be correct.
The exposure changes times, so the intensity of the beam doesn't change. I assume the beam penetrates just too far. If a layer cures the next layer will also cure.
5. The dlp does change brightness in the same way, so using a gray instead of white will most likely show the same results. So I decided to use an ND filter instead to reduce the intensity of the beam.
I had a ND4 filter, large enough to cover the projector lens, at hand. So I used that. And this allowed me to find a setting which operates well at 50xy/50z. The prints have a very slight blue cast under certain lights, but it's not annoying.
On the first look the model looked fine,but the resin is so viskose that it is covered in slabs of uncured resin. Trying to wipe it off will just smear it and introduce some lint. The left most model in the picture shows the slabs of resin.
6. The resin is easily cleaned with IPA, but when the resin gets in contact with IPA it will cloud. Cloud like in translucent, but not clear or transparent as can be seen on the two model on the right of the picture.
7. Using ultrasonic with water only for a minute didn't clear the resin. It still held on. So I tried to get rid of the fog. Using wet sanding helps, but it is tedious or depending on the model a pain. Using a tumbler gets a smooth surface, very nice to the touch but not much clearer.
8. After Eight tries I decided to give it a last chance. I choose a more elaborate model and kept it away from IPA, didn't even speak the word. Put fresh water in the US cleaner and cleaned the model for 30 minutes, checked and did another 30 minutes and moved it directly under the UV lamp for curing. And finally this looks ok. Interesting enough, this model seems to have a slight yellow cast, while the smaller models had a blue cast.
The resin stood for two days in the vat before printing the bear, so the colour of the cast might be a result of not stirring it enough before printing.
Time will tell whether I have to seal the model with some UV-protection-spray.
How it was done
Put a ND4 filter over the projector lens.
Use the following parameters for 50xy50z at 0 lamp hours using a 1.1 B9 Creator:
for 50xy25z at 0 lamp hours using a 1.1 B9 Creator:
Note that the pr exposure time is very high, you might get away with lower values.
Clean with water only, no Ai Pi Ey, don't even think about it. I put it in an US-Cleaner for a total of one hour.
The non-clear model painted and the clear bear (right click on the clear bear image and open in a separate tab or window, for a larger view):