Smooth-Cast Onyx Fast - Ultra-Black Urethane Resin (Gallon Unit)

There is no shortage of different PU based casting resins... this is the best I have tried so far. You have to work very fast... you got 2 minutes only. The material gets very hard, yet not overly brittle. Unfortunately it is one of the most expensive resin of its kind. Here a few tips: Use rubber gloves, this is a messy procedure... Measure into two separate cups. If you use one cup only you need more time, which you do not have. Pour cup 1 into 2, stirr 5 time, then pour 2 back into one and stirr 5 times, then pour into your mold and get it into the pressure vessel ASAP. Pouring from one cup into another reduces the chance that you have unmixed resin in your cup.

You really have to pre-mix the ingredients well or you wont get a good solidification. You have to be skilled at working quickly and mixing for the FULL amt of time as described by the manufacturer. Do not start with your final project. Start with tests. Plan sacrifice at least 2x 50mL castings toward testing and getting to know how the material behaves. People complain about it expiring quickly -- smoothon sells a little can of heavy/dry inert gas that you can spray over the bottles and store them (probably a mix of argon or something). I cant comment too much but used the gas and no problems so far.

Works very well, I have ordered several times and haven't run into to many problems with this product, sets very fast so getting it to evenly coat has been a challenge, but working with smaller batches seems to help with that problem. Overall great product!

I love the final material. It compares well to any quality black plastic mass produced gadget. However, my first try taught me I must use a timer. [see image] I was stirring, no problem, still fluid. I stopped stirring, picked up the mold, and poured ... um. That’d be a nope. It solidified in the time it took me to pick up the mold from right in front of me. Set a timer and don’t fudge it. When the pot life ends it does not start getting gooey; it goes solid. It’s very hot to the touch and takes quite awhile to cool. Be patient. Do not touch. I had a lot of bubbles but mostly that’s because I grossly overestimated how much to mix and instead of rotational casting it filled up the mold all the way. Whoops. I didn’t have a chance to do anything more than tappity-tap-tap, plop, plop. If you can, maybe try mixing a small amount to brush onto your mold and then mix the rest and pour that? 🤞🏻I don’t have a pressure or degassing setup but doubt it would’ve helped me. Most of my bubbles were on the top/back because my mold was intended to be rotated. Air was caught under the top. I might redo the mold and put the opening at one end, on the top, so there will be less roof space to hold the bubbles. My mold was overfilled with the opening in the center of the top so I could not tilt it to set the bubbles free. The gnarly bit on the corner of the second attempt is from a flaw in my silicone mold. The Onyx Fast replicated that error perfectly. I did not use mold release in a fairly generic homemade mold and it pulled out of the silicone easily. I tried to use scissors to remove the flashing around the edge but it’s too rigid to cut with scissors. Sanding, filing, or grinding is probably the way to clean it up. The bottles are horrible for pouring. Be ready with a rag. Part B was especially messy. The end product is great looking and feeling. If you can avoid my mistakes you will get a very professional result.

La marca Smooth-on posee productos excepcionales, en mi caso soy ingeniero mecánico y se que producto comprar al acceder a las fichas técnicas, sin embargo, seria bueno que para cada uno de estos productos vendidos por Amazon se agreguen los valores de su ficha técnica, e imágenes comparativas entre los productos de Smooth-on con aplicaciones comunes para que las personas del común se animen a utilizar estos productos para sus proyectos. / The Smooth-on brand has exceptional products, in my case I am a mechanical engineer and I know which product to buy when accessing the technical sheets, however, it would be good if for each of these products sold by Amazon the values ​​of its technical sheet were added. , and comparative images between Smooth-on products with common applications so that ordinary people are encouraged to use these products for their projects.

This is definitely not for beginners. With the 2min pot life you really have to be 100% prepared to pour. I have noticed that this resin will only mix properly in cups made of certain plastics. Some plastics will cause the resin to bubble and boil. It also gets extremely hot during the 10min cure, so don’t get it on your bare skin or hold the mixing cup after you’ve poured, especially if there is anything left in it.

Professional grade product that yields great results every time

Disappointed to say the least... Followed all instructions with mixing ratios, temperatures, etc, but still wound up with inconsistencies in the plastic setting up. Some areas of the resin remained gummy and oily without full curing. I was insetting the resin into a frame of walnut, mahogany and maple so now I’ve not only wasted my money on the resin, but I destroyed the specialty woods and the time put into working with the wood elements of my project. I have experience with casting/molding resins, and never had these issues. Tried this brand since it is already colored so I wouldn’t have to add colorant separately... big mistake.

Used this in making a resin face mask, preformed extremely well, proved very easy to use this being my first attempt, and resulted in a nice finish. Word of warning though, this stuff cures FAST, like steaming because it's so fast. Just keep that in mind. Also, I think that ideally throwing it in a degassing chamber might be helpful as I did notice a couple of air bubbles in my cast. Overall though, I can recommend this product.

cures very fast so small batches is required when it is cured it’s incredibly strong, i previously used smooth cast 305 for the same part and it would flex under stress. the onyx does not flex and is quite strong but will snap at a certain point. i used this resin to make custom engine parts (throttle wheel and small sensor bracket) and it holds up well so far, no noticeable reaction to heat or gasoline

I have used it many times

good