Step 1: What You Will Need
For this instructable you will need the following:
- PVA Glue
- Talc Powder (material to be bound)
- Mixing cup
- A harp inter-dental cleaner
- A Dremel multi
- A palette to spread samples on
- A spreader
Step 2: Make the Mixer
An inter-dental cleaner mounted in the chuck of a Dremel makes an amazing mixer for small batch mixing. Check out my instructable for one here: Dremel Small Batch Mixer
Step 3: Make Up the Mix
Everything for this instructable was done by weight (I don't know a better way of making direct comparisons between viscus liquids and very aerated solids)
I put 50g of glue into the mixing cup
This was followed with 50g of talc.
I used the Dremel mixer to agitate the mix for approximately 3 mins.
I have to admit that even though I had covered the top of the mixing cup I may have lost a couple of grams of talc into the air as I mixed. Should I do this again I would put the talc in first and add the glue on top to prevent the spray into the air.
I made a second batch, still at 100g but this time it was 30g glue and 70g talc.
Step 4: Spread for Drying
I made up a sample palette in order to test the samples against each other.
I found a cardboard box that for some reason is so waxy that PVA glue does not stick to it.
I laid out a sample of pure glue as a control
I then spread out my 2 samples 50/50 and 70/30
I did my best with the spreader to make sure that the samples were a uniform thickness all over and that they were all as thick as each other.
The samples were left to dry over night.
Step 5: Release the Samples and Analyise
After the samples had been given 24 hours to dry (3 of them on top of a warm radiator), I gently removed them from the palette.
As expected the pure glue sample was clear, as far as I know a thin layer of PVA always dries clear. The other 2 samples were white due to the talc.
Now it was time for a suite of tests...
The control sample was very soft, like a piece of laytex
The 50/50 sample was tougher but still extremely flexible but more difficult to stretch
The 70/30 sample was very firm but still flexible, I could not stretch it at all but it did not tear either.
Cutting all samples with a sharp box cutter was possible but as expected as the mix got thicker, the cutting became moe difficult.
Step 6: Machining and Shaping
As the aim of this instuctable was to make plastic I wanted to see how workable the material was.
Using my Dremel multi and a small sanding drum, I set about trying to create a straight edge on each sample.
The control was so soft that it just flapped about when the drum contacted.
The 50/50 took a good clean edge, however the glue did melt a little with the heat of the friction and started to create quite a large burr that had to be sanded off afterwards.
The 70/30 was the best sample to machine, it took a good straight edge with a considerable amount of work from the Dremel, (considering I have used this same attachment to shape small metal components). There was also minimal burr afterward for cleaning.
Step 7: Burning
If you are making parts or models, you want to know how flammable they may be,
For this I introduced the samples to a direct flame:
The control burst into flames immediately, the flames were large and produced considerable smoke, this is not surprising considering it is made from pure glue..
The 50/50 took a flame for about 60 seconds before catching fire, the flames were small and spread slowly but what remained was obviously mostly talc and so crumbled into powder.
The 70/30 took a direct flame for more that 3 mins before it caught fire, the flames were very small and extinguished withing 3-4 seconds after only travelling 2mm in from the edge.
Step 8: Forming
This was the test I was most interested in.
If I was to make large sheets of this material, could I use heat to form it into a shape and set it.
I applied indirect heat to the samples and shaped them to 90 degrees over the edge of my bench while hot, I allowed them to cool and set to the following effect:
The control bent under it's own weight, then cooled and placed on a flat surface it returned to flat.
The 50/50 sample took the bend quite well with a relatively small amount of heat, however once cooled and placed on a flat surface, it lost some of the set and the angle opened up by about 20 degrees.
The 70/30 sample took considerable heat before it bent, once it cooled and was placed on the flat surface it held the exact angle it was set to, it is still pliable but it always tries to return to the 90 degree angle.
Step 9: Conclusions
I have 2 future ideas for this material:
1. pour it over an existing item and use it to create a negative, I will then coat the inside of this negative with a release material such as wax or Never Wet and then refill with the same material to create a replica.
2. Use an existing mold, like the ones used for plaster molding and fill with this material, i don't know what the drying time for such a large block would be, but that may be another instructable.
It didn't quite turn out like the plastic I was expecting but I think it did become something useful. I am going to try again with a different solid material like sand or sugar and see what the effect is on the final product.
If you enjoyed this instructable please vote for it in the glue competition, thanks