Resin Tutorial

1. Making your prototype.
I don't make my ring or bangle bases from scratch. I tried and didn't have a lot of success. the Plasticene I'm using is very soft and doesn't make rigid forms like rings etc very well. So I shortcut by buying cheap acrylic rings and bangles. You can get bulk rings on Ebay very cheaply, or pick up some of the wonderful 80s inspired plastic jewellery that seems to have sprung up everywhere again, like brightly colour pustules on the butt of fashion.
So either way, make your ring, or use an existing one, now your going to add the design elements. I use plasticene to make my jewellery prototypes as it doesn't dry out and doesn't shrink like clay, and isn't expensive like Sculpey and Fimo.
An important point! If you are going to make your mould from RTV silicone, as I do, then you have to make sure that the clay you are using does not contain sulphur. Sulphur stops silicone from curing, and you'll end up with a goopy mess rather than a mould. And silicone is pretty expensive! I bought 4 kg from Adelaide Moulding and Casting Supplies for $25 bucks, and that's enough for a looooooot of jewellery. If you're not sure if your clay has sulphur in it, do a small test with your silicone before casting your prototypes. (kinda gross that cheap kids modelling clays can have sulphur in it as a filler material!)
2. Made something your happy with? Check out this video from Aldax. It's an excellent tutorial that shows you how to use RTV silicones to make flexible moulds (important if you wish to make reusable resin moulds).

You can make moulds from a lot of different materials. Plaster is difficult as it is rigid, you'll need to coat the mould with a mould release and then chip it away a lot of the times (there are methods where you don't need to, but that's kinda complex, so a book on mould making for you if you wish to go down this path). You can also use latex, which is a brush on liquid. Kinda laborious process and stinky! Also you need to know what kind of resin you are putting into a latex mould as polyester resin (which I use) tends to degrade latex over time.

I like silicone as it's easy to use over and over, gives great reproduction (I have finger prints reproduced all over my jewellery!) and is relatively no fuss. But it's expensive. I get my silicone from Solid Solutions and a huge 20kg bucket (you can get much smaller quantities!) it's about $200 bucks cheaper than most other Australian sellers, so I'm happy.

What you don't see in the video is that if you are using plasticene, you'll then need to scoop it out of the mould. It's pretty easy, sometimes you can simply flex the mould and bits will pop out quite easy, but, if you need to dig plasticene out, like I often do, get yourself a wire tool

The ones with the little loops on the end are the best for getting clay out.

Now, it your mould is free of plasticene and the original ring (should just pop out, like the video) then you're ready to cast!

3. Which resin? I use polyester, because it's cheap and readily available where I am. Epoxy, another commonly used one, is about three times as expensive where I am, but there are some cheaper craft Epoxy's I think on the market, especially in the US. Each resin has it's pros and cons. The big thing with polyester resin is it's catalyst (very corrosive and dangerous to get in eyes and on skin!) and the styrene fumes that polyester gives off. Styrene is a weird chemical, I think I was reading something about it mimicking, or affecting different endocrinal processes?

Wikipedia has this to say:

"The US Agency for Toxic Substances and Disease Registry (ATSDR) states that human exposure to high levels of styrene (more than 1000 times higher than levels normally found in the natural environment) may induce adverse nervous system effects. These health effects include changes in color vision, tiredness, feeling drunk, slowed reaction time, concentration problems, or balance problems [4].
Styrene is classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC).[5] The U.S. Environmental Protection Agency (EPA) does not have a cancer classification for styrene, but is evaluating its potential carcinogenicity. The EPA has described styrene as "a suspected carcinogen" and "a suspected toxin to the gastrointestinal, kidney, and respiratory systems, among others."[6][7]"

So it was very bad of me to follow in the footsteps of my ex partner, and do my first few casts mask free, no gloves, in the good ol Darwin tradition of ignoring all health risks and doing it anyway, standing in your thongs, cigarette in one hand and a flammable liquid in the other...

Yup, well I got some on my skin and it stang! Quickly washed it off and used some acetone to get it all off (acetone removes polyester). for the rest of the day my skin crawled with the kind of weird allergic reactions I get to things. the next time, when I wore gloves, I still got all crawly and itcy from the smell! So I now use a respirator with a P2 filter, and whilst some people think these are next to useless, I definitely no longer smell the stinky styrene smell. I also got some LSE resin (Low Styrene Emitting) which also helps. I use latex gloves, (tried big corrosive resistant ones but were too bulky to use), I use another respirator when sanding and safety glasses, wash all my clothes once I'm finished mucking about with resin, seperately and try to be a better OHS bunny from now on. No more crawly skin or allergy.

Must be extremely careful when using the catalyst and the resin. This is probably not a process to do around children. I do all my casting outside, at the back of my house, with safety gear and no kids. It apparently takes huge amounts of air to dissipate Styrene fumes, so not so good for little lungs playing in the backyard as you make jewellery. Epoxy might be much better in this regards? Not sure, I don't know that much about the different resins at this point.

Make sure you recap catalyst bottles safely, keep all these chemicals out of reach of kids etc

I use fibreglass resin, I don't do a lot of embedding so I don't need the water clear effect polyester casting resin has. Fibreglass resin looks a lot like honey, is thick and yellowish and goopy and I colour it with polyester resin dyes, oxides, and resin paste colours. You don't need a lot of any of these to colour your resin quite deeply.

4. Okay. Mould on flat even surface, clean, dry and free of plasticene. Resin and catalyst, kitchen scales, disposable plastic cups or some other mixing vessel which you won't be able to reuse for anything else. Flat stirrer (paddlepop sticks, or tounge depressors are good). Dyes or stuff to embed (glitter, hundreds and thousands etc).

You can work out exactly how much resin to use by filling your mould up with water, then emptying it into a measuring cup (or a plastic cup and marking the level with a pen). I have so many moulds I measure out my resin per hundred grams and then fill as many as I can.

Measure out resin on the scales. The catalyst bottle will give you a ratio (often 3ml to 100ml on cooler days), so if you don't know the weight of your resin, you won't know how much catalyst to put in. Too much catalyst? Your piece can crack from the heat generated by the catalyst. Not enough? Your piece will be tacky and gooey. It's important to be fairly precise.

Don't add catalyst yet! Add any colour, dye, or additions now. Stir them through with your paddlepop stick until mixed through then add the catalyst.

Catalyst must be measured in a container not used for other things. Silicone catalyst and polyester catalyst apparently are hazardous if mixed. I got tiny little measuring cups from my local hardware store. Measure it carefully but be aware, one little splash of this on skin or eyes (or anywhere else for that matter!) is very hazardous, so keep your distance and be careful when measuring.

Add catalyst to resin, stir through thoroughly and then pour carefully into your mould.

Sculptural resin jewellery moulds often have problems with air bubbles than most. there was air, obviously, in your mould when you started and pouring the resin into it displaces that air. an open mould (one with smooth rounded shapes like the ring in the video) will have few problems, but ones with little protrusions like my stuff, air will tend to get trapped in these cavities in the mould. The resin is rushing in, but no where for the air to go in the small space.

There's a few solutions to this

1. agitate your mould. I usually use a paintbrush handle or something and try and wobble the mould to get all the airbubbles out

2. You can create a pressure chamber. Apparently people do this using paint pots (the kinds used in high pressure spray painting) and attach them to a compressor and get the psi up to about 20-25? I don't know much about this, it's beyond my technical capacity right now, but apparently this gets rid of a lot of air bubbles

3. Dust your mould with talc. Not sure how or why or if this works, but I've seen reference to it as a technique

I always slightly overfill my moulds. Polyester likes to 'creep' up the sides of moulds, and as it sets, seems to almost 'suck' back into the mould. if you have details right on the surface of the mould, you'll lose them as the resin 'sucks back'. By overfilling, you end up with a blob of resin on the end of your piece which you have to later remove, but you get all the detail.

Now let it set. The directions for your resin will give you approximate times as to how long this will take. Basically the moulds will get hotter, as the chemical process takes place, and then it will cool down and the resin will get steadily harder. Be careful about being too gungho and pulling your pieces out when still a bit soft. You can distort and mark the surface of your piece if you wrestle it from the mould too early

5. Remove pieces from moulds and then clean them up.

If you have resin blobs you want to get rid of, now's the time to pull out the trusty Dremel. I was trying to do this with hand tools initially (files and sandpaper) and it can be done, but it's time consuming! Just a note though, power tools will often turn resin white due to the heat generated by their use. I use a Dremel with a coarse sanding wheel to take off most of the blobs from my work, and then go back and sand them smooth by hand, removing the white marks.

You can get polyester to a very high shine...if you're patient. this means going through different grades of sand paper, getting finer and finer as you go, until you end up with a very smooth surface which can then be shined up. I like matte, it's easier and looks pretty!