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First Thoughts: Resin Color Kit

Hi folks,

Your friendly neighborhood bagpipe maker here. I’ve been prototyping some pennywhistles based on a certain production run of a 1970s product that was much sought-after in the traditional music community.

After I found that my planned production method of bulk SLS printing couldn’t achieve the surface finish required for a woodwind instrument, I decided to make a few of my early production models here at home. The color kit had some really nice options available in nearly the exact final color I had planned, and the ability to simply buy some more base pigment made it cost-effective to experiment with some of the other dyes if I wanted.

The instructions for mixing the dyes with the base were very clear and easy to follow, although I’m embarrassed to admit shaking a resin cartridge for four minutes straight was a bit more of a workout than I expected. I appreciated that they included a time for mixing, because that sort of precision gives me confidence that a) the result is validated, and b) consistent results will be achieved so long as the method is followed.

The resin itself was much smellier than the Clear V4 I am used to, but perhaps that’s expected with something that has to polymerize through a screening of pigment particles.

Initially when I pulled the first prints, I noticed two things. One, I assumed that the resolution had taken a hit, as the parts seemed more melty looking that I am accustomed to (frankly it looked like the world’s worst blueberry yogurt). Two, this resin LOVES the build plate and I broke most of the rafts extricating the parts, careful though I was. Some of the resin on the raft didn’t appear to have been cured that evenly, and I ended up scraping the build plate clean and re-washing it with IPA before returning it to the chamber.

After a ten-minute slosh in the IPA, the details really came out and

I think the resolution is as good or almost as good as the standard clear

I have since noticed a slight loss in resolution; unfortunately, this rounded the windway floor exit face, almost completely killing the instrument. I plan to offset this face slightly and then sand it flat, but it’s something to be aware of if you’re after fine detail on critical surfaces. My printing orientation could also be contributing to this; I am investigating.

I post-cure all my resins just to harden them so I can work on them right away with files and sandpaper. In this case I used 15 minutes at 60 C, flipping the orientation of the parts halfway through. Overall, the finish is pretty good without a lot of stepping or layer bulging. There’s a bit of pitting on some of the flatter surfaces (I assume from the IPA), but nothing that can’t be sanded out with 400 or 600 grit.

Now for the not-so-good part. I think Formlabs really needs to put greater quality control measures in place with its resin. Mine was fulfilled through “Omni Logistics” and right off the bat the box smelled “warehousey” which made me wonder about the storage conditions. They’ve at least started sealing their cartridges in plastic; the last one I ordered was loose in the box and missing half the resin (Formlabs customer service did send me a replacement for that one.) Just out of an abundance of caution, I checked the bite valve before installing the cartridge to verify it was fully cut (it was).

My happiness was premature, however, as in the morning when the print had finished I saw flecks of some kind of white substance in the resin. I understand that the mixer helps redistribute the dye particles (so ignore the “pillowing” lines in the photo, but these flecks were bigger. They could not have come from the inside of the printer cover, because not only was it very clean, the flecks clearly appear under the point where the resin is dispensed. Some of these did show up embedded in my final product, though thankfully in this case only on the inside surface where the windway floor is installed.

[See images here]

Frankly this is pretty frustrating. I have given Formlabs the benefit of the doubt in many cases where I’ve read negative reviews, simply because I know what it’s like working around high-precision laboratory instruments (I’m an ex-QA analyst for a surgical tools company). There are certain implied steps and care for these things that not everyone is aware of, and you can never be certain whether the printer is in an access-controlled environment or not.

However, if the price and shelf life of the resin are supposed to reflect the cost of consistent results, I’d say Formlabs is falling short in that regard, since not one but now two resin cartridges purchased directly from them have had issues. I’m going to contact them about this and I’ll report back what they say. I really don’t want to manually clean this brand-new tank, either. If I can’t get this sorted soon it’s going to push back my launch date for these, and I am not excited about telling my pre-order list there will be yet more delays.

I couldn’t find a lot number on the color base or its packaging, only a sticker reading:

Color Base V1
2020-01-17s


I will update this post after my hand finishing steps and play testing. Pennywhistles are made or broken in thousandths of an inch, so an accurate blank coming off the printer is important if hand finishing is to be successful. So far with the clear resin I have been very impressed with the consistency of the results. Some might turn out marginally better, others marginally poorer, but overall I can count on making the same instrument with the same tonal character every time.

There are white flecks or clumps in mine, as well. I suspect they are clumps of the white pigment. I expect filtering them through a fine mesh strainer should remove most or all of these large, insoluble particles.

By the way, do you see a small amount of “flashing” on the first layer or so of your prints using Color resin?

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Ah, but here’s the rub - I didn’t add any white pigment. Also, the particles are quite hard and about 0.5 to 1mm long.

I haven’t experienced that kind of flashing, although I did get some rippling on the rafts (but not the piece itself).

Interesting. Maybe the white flakes are in the base pigment? Either way, filtering those off through 190 mesh or finer should remove most or all of them.

I don’t really have a way to do that. I’m working in an apartment, and although I have specific chemical waste containers for the IPA and any leftover resin, I’d have to get disposable pails, mesh etc and it would just generate too much waste for what I have to work with. Plus, cleaning the tank risks inflicting damage to the membrane and certainly reduces its lifespan.

I think the broader point is that I’ve now received two resin cartridges with quality control issues, and especially considering the price of the material and the tank, I don’t feel I should have to perform an inconvenient filtering process on a new product, nor a cleaning process that shortens the lifespan of yet another purchased-new product.

I’m just going to contact support, although I appreciate the suggestion.

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