How much putty to use:
When you're new to molding, it's hard to know how much putty to use. What I like to do is picture how much clay I'd use to make the item I'm molding, then use 2-3 times that much putty. In other words, if the button I'm molding would take about 1 teaspoon of clay to make, I'll probably use 2-3 teaspoons (combined) of the mold putty mixture. Of course, you may like thicker molds, so as always, play around and figure out what works for you.
What to do if you mix too much putty:
Once you've mixed the two mold putty parts together, you have to use it (no putting it back in the container). To avoid wasting putty, keep a few extra buttons handy, and mold those with any leftover mixture.
What to do if you didn't mix enough putty:
If you've worked quickly and still have some time before the putty gets too firm to take an impression, measure out some more putty and add it in. Apply extra pressure as you're rolling it into a ball, and beware of creases. If the putty's already starting to firm up, it's probably best to go ahead and let it set. Then use more mold putty to "patch" the weak or incomplete areas, letting the whole thing set again before using it.
I mentioned previously that Amazing Mold Putty is oven-safe. While I haven't found that to be a huge advantage for normal clay use, it does create some interesting options for liquid clay. Try tinting some liquid clay with alcohol inks and putting a small amount in the mold's impressions. Fill the rest with "normal" clay for a neat effect.
More mold putty uses:
Hiflex DIY Putty is Food / Medical Grade, so you could also use it for things like candy & jello molds.
The basics are the same regardless of the brand. When you purchase these products, you get two different colors of putty in separate containers. To use them, you mix the two colors together until they're blended, then you shape the combination over the item you want to make a mold of. Once the mold putty is set (setting time varies by brand), you peel it off whatever you molded, and it's ready to use. At this point, you can use the mold just like you would any of the commercially available clay molds.
One advantage of the silicone molds over commercial molds is that you don't need a release agent. The clay pops right out of the silicone. In fact, I've occasionally run into problems with the clay sticking to my fingers more than to the mold -- a little corn starch or talcum powder sprinkled on top of the molded piece helps with that. Another advantage of silicone molds that I've seen touted -- and that may be useful to some of you -- is that many brands are oven-safe at polymer clay temperatures. This means you could bake your clay right in the mold. Of course, if you're like me & like to tweak your molded things before baking, this may not be a big benefit to you.
Making a Mold
1. Measure and mix equal amounts:
Mix equal amounts of the different-colored putties together until they're a uniform (not marbled) color. If you're using Hiflex DIY Putty, don't stress too much about getting precisely the same amount of each color. Just roll out balls of putty that look roughly the same size.
2. Roll into Ball:
Roll the putty mixture between your hands to eliminate creases. In my experience, applying pressure to really compress the putty ball helps here, especially if you're nearing the end of the putty's workable time.
3. Mold and Set:
Shape the putty over whatever you're molding, pressing down completely to get a good impression. If it works better for the item you're molding, you can also put the mold putty on wax paper (it sticks to regular paper!) and press the item into it. If you're molding something large and flat (like for texture sheets), you can even run your mold putty through the pasta machine first to get a thin sheet. If you find you've mixed up more putty than you need for your item, quickly roll the excess into a ball and find something else to mold. And you do have to work fairly quickly: depending on conditions, 5 minutes is about as much good molding time as you'll have.
After you're done molding, let it sit undisturbed, according to the package directions (Hiflex DIY Putty sets in 25-35 minutes).
4. Tweak and Use your Mold:
Once it's set, your mold is ready to use as is -- or you can tweak it some more. The mold putty will stick to itself, so if you happened to get a thin spot in your mold, you can patch it with more putty and allow it to set again. You can also cut the mold with scissors or a craft knife -- which is really handy for cleaning up edges on texture sheet molds. To use the mold, roll your polymer clay into a ball, eliminating all creases. Press it into the mold, then use an aluminum scraper to trim off any extra clay, leaving the back of the clay even with the top of the mold. (You can also use a clay knife to do this, but be careful not to cut the mold!) Gently press the clay out of the mold, then make any necessary modifications before baking. If you have a thin, flat mold, you can use a brayer to press it into a clay sheet -- or you can even run the mold and clay sheet through the pasta machine together.
Ideas for Molds
You can make molds of anything.
Here's a few ideas to get you started:
Jar of Buttons:
Want to make handmade polymer clay buttons to match some wonderful fabric? (Or to replace a missing button?) A button mold is a great way to keep all your buttons the same size and shape. Button molds are also a fun way to practice your molding skills -- grab that big jar o' buttons and start playing.
Make your own texture plates by finding interesting textures and making molds from them. Try baskets, lace, leaves -- or anything else that's got a great texture. You could also use extruded clay to make interesting patterns on a sheet of clay, then create a texture sheet from that.
Once you get the hang of making your own molds, you'll really appreciate what a wonderful tool molds can be. Did you create one earring & want to make sure the other matches it perfectly? Make a mold! Want to mass-produce a favorite handmade polymer clay creation? Molds are a great way to speed up the process.