As recommended by their website, it takes 30 seconds to mix, and you should have it in place a minute later, then it cures (hardens) in 3 minutes. The instructions that came with it say it takes 24 hours to fully harden.
Each time I tried it, I gave it the 24 hours before I started messing with it.
The white part was a little oily, so I'd suggest washing your hands after using this stuff, especially before going back to hobbying.
Don't waste any time between mixing the Blu-Stuff and pressing it over your object. Once it starts to harden, you won't be able to capture much detail.
Once it fully cured (24 hours later) I used a hobby knife to trim the edges so the head would come out easier, then used the same knife to pry it out.
Then, I mixed up some Green Stuff, and firmly pushed and worked it in.
* TIP: Normally, you mix Green Stuff 1 part blue to 1 part yellow. When working with moulds, use more yellow. I did about 3 yellow : 1 blue. This makes the Green Stuff softer once it's mixed, and will let it pick up the details of the mould better.
Once the Green Stuff fully hardens, you can use a knife or other flat tool to carefully pry the faces from the mould. I was very pleased that the Green Stuff didn't stick to the Blu-Stuff at all.
Here are the two faces I made from that one mould:
|Better than Failcast|
You'll notice they're not perfect. Both had bits of Blu-Stuff stuck to them, which suggests that every time you use the mould, you'll lose a little more detail. The first one is pretty good, eyebrows a little rough, and the left nostril is messed up. The second one's eyebrows are noticeably rough, the nostril even more so, and you can see part of the eye hole still in there.. that meant the eye looked alright this time, but next time it won't be.
Now, a couple things to note:
First, Blu-Stuff's website, while not specifically saying so, only shows using it to clone iconography. So small, flat, almost 2D details - not complicated 3D ones.
Second, while this won't help everyone, it's fine for me that the faces are rough. I cut out any errors from the faces, drilled nostrils, etc. I don't want all my faces to look the same anyways, so I was already planning on adding a few more layers of Green Stuff over these "basic" heads.
Even then, once you cut them out, and compare to the original, things look pretty good:
|Notice the difference in colour... Not only are the copies much lighter since I used more yellow,|
but the original is much darker since I used more blue on it for a firmer sculpt.
It's not bad, and I'm sure it's great for small, low-detail projects.
The clones aren't bad, but I still think I'll keep the original around in case I want more, rather than rely on the mould lasting. After making those two heads, enough detail broke off the mould I had to make a new one.
I'll keep using it as long as I have it, but I'd try a different brand and moulding technique before buying it again. Generally, moulds are supposed to be reusable.
Although it is cheap enough that you could plan to make one object per mould and still save yourself many hours / days of sculpting the same object over and over again.