Mold Star 15 Slow - 1A:1B Mix by Volume Platinum Silicone Rubber - Pint Unit

I have worked with this company's materials before and I have never been disappointed, nice fluid plastic that sets up quickly and casts with very few air bubbles. - Easy to use 1to1 mix ratio.

Mold Star 15 Slow has been fantastic for my projects. It captures fine detail really well and gives me consistent, bubble-free results. The longer working time is a huge plus when I need extra time to get everything just right.But what really stood out was the customer support. I reached out to Smooth-On directly to figure out which silicone would be best for what I was doing, and they walked me through everything step by step. Later, when I had some trouble with my mixing technique, they were super helpful and patient—totally saved me from wasting materials.Great product backed by a great team. Highly recommend it if you're getting into mold making or want something reliable with solid support behind it.

I've tried a lot of molding silicones from a few brands, and so far, this one's my favorite for a handful of reasons.1. Long pot life means there's ample time to mix and pour before things start to thicken up on you. If you're like me, when you first start making your own molds, you'll find dozens of ways to screw things up. A nice long pot life means that if (or in my case, WHEN) things go haywire, you'll have plenty of time to fix things. Silicone isn't cheap, so mistakes can be expensive -- the wiggle room is nice!2. Relatively quick cure time, especially given how long you have before the mix starts to solidify. I can come home from work, pour a mold, and it's ready to use with time to spare before I need to head to bed.3. Platinum cure is always a plus. For mysterious reasons, I've had trouble with tin cure silicones and the material I usually cast (epoxy). I think post-curing tin-cure molds is supposed to solve part of the issue, but even when I've tried that, the tin-cure molds have left a slightly tacky, sticky film on the surface of my castings. I've had much better luck with platinum silicones, which actually seem to *improve* how my epoxy resin cures.4. Low viscosity means you don't get bubbles as long as you don't overmix, and the trapped air in detailed molds doesn't have shove its way through super-thick goop to break free. In other words, unlike a lot of silicones, you can get excellent results with this one without using a vacuum degassing thing-a-ma-bob.The last thing is a plus/minus: This stuff is soft, but not insanely soft. The flexibility makes it excellent for intricate stuff because you don't need Hercules hands to get your casting out of the mold. However, really soft, flexible silicone like this can also cause some problems. So here are a couple tips I learned the hard way :).1. If you'll be casting something in multiple layers, make sure you either place your mold in some kind of support shell -- a cup or a plastic bowl can work -- or make your mold with extra "buffer" rubber on the base and the sides. Why? Well, if you move the mold too much, those awesome natural silicone release properties can work against you and knock your layer loose, which means the next layer can ooze down the sides. Having something to make sure the soft mold doesn't get jostled makes all the difference.2. On a similar note, if you're going to make one mold with lots of cavities, it's probably best to time things to everything is ready to be popped out of the mold at the same time. The flexibility means it's pretty easy to accidentally knock one casting loose while trying to remove another one.All in all, a really awesome product. Highly recommended!

This makes terrific strong molds, fast and easy. If you use a single graduated container and pour in the same amount of A and B, then cleanup is very fast and easy because you can just wait for the residue to set up in the container and then it just pulls out all in one piece.The instructions clearly state that it will not set up in the presence of sulfates, but I didn't realize that most resin prints have sulfates. This will work great with regular (FDM) 3d printers, but not for resin printers unless you get special resin!

I bought this trial kit to tinker around with concrete casting, after 3D printing, sanding and finishing a master copy of a small planter I built a mold box, glued the piece down, and mixed up the proper amount (about 2/3rds of this trial-sized kit) then poured the mold.The mold came out fantastic and I've cast about 10 concrete planters off of it so far, all of which come out looking great, the product works just as intended and I'm very happy with the results.My one complaint is the price, after searching everywhere online for cheaper alternatives what I've found is $30 for 2lbs is pretty much the norm. I think it has something to do with the platinum used in platinum cure silicone. What I don't understand is I can hop over to Walmart and buy ten pounds of silicone kitchenware for $20, and I'm aware it's not made out of quite the same stuff, but jesus, to make a mold for anything substantial, a lawn ornament, a large planter, or whatever, I'm looking at $100-$200 for one mold!If anyone out there can point me to a competitor with better prices, I'd be grateful!