Hello, I tried shell casting when I started working on my project but after 6 months of failures I decided to go with vacuum-assist casting (jewelry) method instead. This worked, but the last 7-10 parts of the project are too large to cast using this method, so I am going back to shell casting. I hope I could get more advice here to help me succeed this time. Here is the largest part I was able to cast with the jewelry process: Fig. 1: Wax positive for 2.7" x 12.4" x 0.7" part attached to a rubber base with sprues, and an extra-tall vacuum flask it will be invested in. Fig. 2: two mirrored parts cast in the same vacuum flask (one of them from the above wax positive) displayed with four copies of another part of the same assembly. Here are the wax positives for the larger parts that I can start building shells on immediately, because they are too large to cast with the jewelry process: Fig. 3: Two mirrored parts, each 6.5" x 9" x 2.5" bounding box. Fig. 4: One of two mirrored parts, 5.5" x 13" x 3" What went wrong last time: I had issues with cracking molds, which I finally solved by switching to Remet red pattern wax (above), only to find out that I couldn't get a polished as-cast surface with sub-millimeter detail on my shell casts. The main issue there was that the first layer of slurry failed to adhere to the wax, due to lots of extruded detail with sharp corners on the wax model. If I used more slurry to force it to cover the wax, it would crack like a desert floor and flake off when drying the very first layer. If I used less slurry, the first layer of flour would end up in contact with the parts of the surface that slurry would not adhere to, so I would get leopard-skin effect on the casting, where some parts were smooth and some parts looked like a sand-cast surface. In addition, many of the smoother parts still had a micro-foam like surface rather than perfectly smooth. I achieved a polished as-cast surface and sharp detail with the jewelry casting method, so I need to find a way to do the same with shell casting. Lastly, the slurry quickly lost its pH even through R&R said it was safe to use the bucket for dipping the parts directly. It changed color to become more yellow, all the sediment settled at the bottom, and then it started turning into foam with more bubbles each time I dipped. I could never get it back to original form, still not sure what I did wrong. Here's my research so far: Resources: Tips from machinemaker: http://www.alloyavenue.com/vb/archive/index.php/t-10459.html Shell building: https://docs.wixstatic.com/ugd/cc5f22_1b16abf7aa264790acb87e31d3ec63f0.pdf Slurry additives: https://docs.wixstatic.com/ugd/cc5f22_0102e9f605bc48ec903f00f2ed6431b7.pdf Slurry control: https://docs.wixstatic.com/ugd/cc5f22_c8b09a4fd433437a9137c10dd2619661.pdf SuspendaSlurry FAQ: https://docs.wixstatic.com/ugd/cc5f22_02c0e31fa28d476c920966b633772c32.pdf Howto videos: https://www.youtube.com/user/jagboy69 Supplies: what should I get this time? 1. SuspendaSlurry FS, 5 gallons Last time I used this as a back-up slurry, and SuspendaSlurry ZR as the primary slurry. I somehow let the salesman talk me into using ZR even through I was casting in Aluminum (non-ferrous), perhaps because I stressed the importance of fine details. This decision doubled the price of my materials and caused me to fail because it's harder to use. I think I would like to stay with SuspendaSlurry because I can only use my hobby space every other day, making constant mixing problematic. This differs from machinemaker's instructions (see Resources section above), as he recommends using Prime Coat with a fused silica flour - however SuspendaSlurry gained widespread use after he posted those instructions, so do you think I could succeed with it, or is it a bad idea? 2. Wet-It wetting agent Recommended by R&R page at https://www.ransom-randolph.com/slurry-additives. Since my primary issue other than shell cracking was the failure of the first coat to adhere to sharp details in the wax model, this seems like a requirement for me to succeed this time. What do you think? 3. Flour Last time I got Zircon sand for use as flour for the primary coat. If I am switching to SuspendaSlurry FS, should I get another flour? Perhaps I no longer need flour (and never needed in the first place)? 4. Fused silica stucco (1 bag of "A": 50/100 grit) 5. Fused silica stucco (1 bag of "B": 30/50 grit) I got these two bags of sand last time to use for the back-up coats. They are standard "A" and "B" presets from R&R, corresponding to medium and large grit. Should I get them again? Thank you for reading - I appreciate your time!