**11/1/14 update. This is now available for purchase in our shop in 100g coils. ** Have you ever had a nozzle clog? :) I'm sure the answer is no, right? That never happens in 3D printing. Of course I'm being sarcastic. Nozzle clogs happen. There are things you can do to minimize them such as using quality filament and installing a filament cleaner, but they're still going to happen on occasion. I've found that they seem to be at their worse when using filled materials and when doing a lot of changes between filament types. Recently, Chinese filament manufacturer Esun released news that they had developed a filament that could be used to clean out the extruder. I've worked in and around thermoplastic extrusion for close to a decade now. I've read several ads in trade magazines for cleanout resin, but have never actually seen it in use as it is not something that made sense for the industries I've supported. The intent of the resin, as far as I could tell from the ads, was to cleanly purge the extruder of one polymer or color of polymer prior to starting a new one with a minimal amount of material waste. I've often had passing thoughts wondering why nobody has tried this for 3D printing, so I'm glad to have a chance to test it. Our friends at toybuilder labs were able to send us some samples for beta testing. Here is what we received: [caption id="attachment_4119" align="aligncenter" width="1280"] A pack of approximately 6" long extruder cleanout filament.[/caption] [caption id="attachment_4120" align="aligncenter" width="1280"] Instructions on how to use cleanout filament. Availability and pricing was cut off, but it was basically TBD.[/caption] Before I proceed with the review, let me talk a little bit about how we print in the Printed Solid shop. Typically, we are switching between filament types on each of our machines nearly every print. It is not unusual for us to go do something like Taulman 645 nylon to colorFabb woodfill to protopasta Carbon Fiber PLA in a single day. We also print A LOT with filled materials like woodfill and CFPLA. So, we're probably the absolute worst case test case for this stuff. We've used it twice now. The first time we tried it was after a long, successful print with white beta colorFabb XT. No black specs were noted in the print. We pressed in a little bit of the cleanout filament and pulled it back out a few times. No real discoloration was noted. Then, we extruded a little bit. Wow! The extrudate was loaded with these little black particles. This indicates that the cleanout filament successfully removed residual PET and got to some kind of charred junk or dark filament residue behind it. Unfortunately, the piece was thrown out in a shop cleaning before pics were taken. After the cleanout, PLA/PHA that was going on for the next print did seems to feed with less resistance when fed by hand than I had noticed prior. The second time was at a customer's shop. About a week prior, they had just purchased a spool of woodfill and experienced a nasty clog less than one minute into the print on a Makerbot Replicator 2. It was actually one of the nastiest clogs I had seen. Of course, I helped them get that clog cleared prior to leaving. Woodfill performs very well in the Replicator 2, so I thought they might have some caked on PLA causing more extrusion problems than normal. When I came back in, we ran through a stick of cleanout filament. A little discoloration was visible on the initial extruded material, but it generally came out clean. We then loaded up the woodfill and ran a perfect Tiki with no indication of clogging. [caption id="" align="alignnone" width="1152"] Tiki by Cerberus333 in colorFabb woodfill. Photo courtesy of Sovereign Air[/caption] So, what's my opinion on this material? I think it does what it claims. If you use a lot of exotic materials like us, this stuff is going to become a standard item in your toolkit. We will be using it to clean before every critical or long print and on occasion as a preventative measure. Constructive feedback for the future? Those 6" sticks are too short. They work alright for printers with a short extruder-to-hot end distance, but if you've got something long like a Wades Extruder and a E3D V5, you're going to be hard pressed to get much material through. I guess these lengths would be alright with a bowden feed because you could push them with another piece of material. It would be nice to have it in 12" lengths or, even better, on a small spool. Other than that? I declare it awesome. Get it here soon!