LayBrick is a new experimental filament from Kai Parthy, developer of Laywoo-D3 wood-based filament. This one consists of a thermoplastic with fine-milled chalk as a filler, and so it prints with a decidedly ceramic look and feel, and an off-white putty color.
I’ve tested it for a few days now on my Ultimaker, and have been very impressed with the initial results. Indeed, I’d say it’s perhaps my favorite printing material at this point. It’s not cheap, and it’s something of a niche product, but it opens up some new possibilities for 3D printing. One of the unique features about this filament is that provides a textured finish that almost completely hides the layering in most circumstances. The cup shown here (click on it to see it larger) is about 6cm high, and was printed with 0.15mm layers. It has a rough, unglazed-ceramic texture, and almost no visible layering. Interestingly, however, the material can easily be sanded to a beautifully smooth finish, and can be softened in some solvents (but see below for some caveats).
For me, one of the great things about this filament is how great the printed items feel when handled. Depending on print speed and temperature, the raw prints take on a texture that ranges from a fine, barely discernible eggshell grit up to the slightly abrasive sandstone finish. But when it’s sanded, it easily develops a smooth lustre that feels like polished marble – and whatever the texture, it always has a slightly warm, natural feel that is not at all like plastic.
The filament comes as a loose, zip-tied spool of 250 grams in either 3mm or 1.75mm. In my testing, the 3mm seems to average around 2.75mm, while the 1.75mm is closer to 1.65mm. I tried spooling the 3mm onto a standard 4″ core spool, but it didn’t seem to like being curled that tightly. It tended to break on the innermost layers, and even the outer layers seemed over-stressed and tended to break again when straightened out again to feed into the extruder.
The first layer is critical for getting a good print. I found that it would stick to cold blue tape pretty well, provided that my first layer speed was sufficiently hot, slow, and thick. I eventually settled on a 0.3mm first layer at 180°C and 30mm/s. Once the first layer was down, I found I could up the speed to at least 60mm/s and 0.15mm layers, and get good results, provided that the temperature was high enough.
The filament has a soft, paste texture when it first extrudes, which helps the layers to blend together, and it seems to show little or no tendency to warp off the bed. However it quickly solidifies to be able to support its own weight, so I didn’t see too much sign of layer droop with a minimum layer time of 7 seconds.
Speed and temperature
I did all of my testing so far at 0.15mm layers after the first one. That allowed for fairly fast prints, with thick enough extrusion for the slightly soft material to hold together in the first seconds until it cooled. And since the layers are very hard to see with this material, there was little benefit to going thinner, although I’d expect it to allow for slightly faster print speeds.
In general, lower temperatures give more precise control over surface finish. I found somewhere around 165º was the lowest I could print at reliably. At this temperature, I was still getting a little under-extrusion printing at 24mm/s. By about 180º, prints were coming out nicely at 40mm/s, and 200º seemed enough to sustain 60mm/s. Above this, I didn’t really push the envelope in terms of speed, but I found that the surface of the extrusion became less precise… details tended to smudge a little more, both horizontal and vertical flat surfaces were rougher, and retraction worked less well.
Bridging seemed to work quite well in all my tests – at 40mm/s, I was able to cover over 20% infill without difficulty in just three or four 0.15mm layers. I printed with the fan on after the first layers, and did see a little fluff developing on the surface of the prints, where the fan would blow spider-silk-fine strands of polymer from the edge of the printhead, especially at higher temperatures. However, this really didn’t interfere with the finished print quality, and easily brushed away.
Retraction works well – much better than I’ve seen with the batch of Laywoo-D3 filament that I tested with last year, for instance. In printing the standard hollow pyramid, I experienced a little blobbing on the inside overhangs, but that was easy to clean up. The outside edges were very clean with no stringing, and the overall result was quite acceptable. I used 35mm/s retraction for 4.5mm. One of the problems you can see in the test print on the right is that the four corners were initially still so soft and warm that when the ‘capstone’ of the pyramid was printed, it tended to push some of the corner pieces out of the way. A slower, cooler print would have helped with that and I suspect would have given an even cleaner print – my main concern with this test was just to show that retraction does basically work with this material, and even complex geometries need not end up a mess of strings.
Surface finish and post-processing
One of the great things about LayBrick is that it can be processed after printing to give a variety of different surface textures. For a start it can be sanded quite easily to a smoother finish – even a perfectly smooth marble-like finish. I found that mechanical sanding with a rotary tool quickly became over-aggressive, causing a heat build-up that melted the material, but hand sanding worked better – particularly wet sanding.
At first the print can be a little soft, but within a few hours of printing it cools and sets into quite a hard surface that holds detail well. Depending on the effect that you are going for, you might want to let the print harden overnight before working on it.
Another interesting property of the material is that it dissolves in isopropyl alcohol. This provides a way to soften the surface for imprinting or embedding another texture, or to smooth and reshape small features such as overhangs. I didn’t find that vapor had much effect on the material, but liquid alcohol immediately began to soften the surface; once the alcohol evaporated, the surface hardened right back up. I haven’t really tried it, but I suspect that swirling in an alcohol bath might be a way to smooth intricate parts that can’t easily be sanded – although that would involve exposing the print to far more alcohol than my limited tests did – and I don’t know how that would affect the print. Kai Parthy told me to be careful using alcohol on the prints, as it breaks down the polymer chains, and can lead to brittleness over time. However, in the limited amounts and limited time that I’ve done it, I haven’t noticed any long-term ill effects on the prints.
LayBrick is an easy-to-work-with and forgiving material that has a striking but neutral appearance that easily hides the tell-tale layering that mars many 3D prints, without needing to resort to ultra-fine layers. I’ve found that the attractive texture and warm feel work well for sculptures and bowls that invite handling, and also for printing 3D scans of people, where the ability to hold detail and yet not look overly layered is a great combination. Architectural models are another area where I expect to see a lot of potential. LayBrick is clearly not designed for harsh environments of high temperature, solvent exposure, or mechanical wear, so its applications will be mostly aesthetic and artistic – but for those, it opens up whole new vistas compared to traditional plastics.