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Wednesday, 28 December 2011

Dinosaur fossils

At the end of January, I'll be running another children's workshop, and this time the theme is Dinosaur Fossils. I've just started putting it all together, but what I really wanted to do was try out the salt dough fossils that I've seen all over the internet: here,  here, and here.
These all look great, but have one major disadvantage for us - they need to be dried in an oven for anything up to a couple of hours! We don't have that sort of time; the workshops last around 1 1/2 hours and I need something that can be completed in that time.

Henry and I had made salt dough cookie-cutter Christmas ornaments which we'd dried in the microwave. This had worked quite well, but I'd quickly realised that to stop the salt dough from bubbling up in the microwave, I'd have to weigh it down slightly with a plate on top. Perfect for flat ornaments, but not so great for fossils!

Anyway, I did find a solution for this (where there's a will....)!

First, the salt dough recipe (this was the test amount I used for Henry and me):
  • 2 cups flour
  • 1/2 cup salt
  • 1 cup water
  • 1 heaped tbsp coffee grinds or 1/2 cup of sand
The coffee grinds/sand aren't necessary, but they give the dough more of a "rock" look which is quite effective.
Mix together until you have a smooth, pliable dough, using more or less water as necessary.
Divide into 4 pieces, and roll out each bit into a circle or oval shape, not more than 1cm thick.
You need a collection of dino-related items to press into the dough to make your fossils and imprints. We used small plastic dinosaurs (great for footprints), a plastic dino skeleton, various plastic plants and some shells we brought back from our holiday.
Press the items firmly into the dough - you shouldn't come through the other side, but if the imprint isn't deep enough, it will disappear during the drying (unless you are air or oven drying, in which case you can probably get away with quite feint markings).

Now you can quick-dry your fossils (one at a time) in the microwave. The only problem with this, as I mentioned before, is that the water escaping the dough doesn't really have anywhere to go and will cause the dough to bubble up (ok if it's only a bit, but any more and you lose the markings).

Here's how I got around this: you need a flat microwave proof plate, with a piece of paper kitchen towel on it. Place a square of baking paper on that, sprinkle with flour, put your dough fossil on top, sprinkle that well with flour too, then another piece of kitchen towel on top. Into the microwave on 600W for 3 mins (but you'll need to experiment as this will depend on the size and thickness of the dough).

When it's done ie more or less dry, take it out and - this is the fun part - with a large paintbrush brush the flour carefully off the fossil and out of all the little dips and crevices (just like a real archeologist!).

This bit is very messy <surveys kitchen counters, sink and self covered in a film of white flour>.

And that's it! You can, if you like, let the fossils dry out completely (I'd leave them overnight on a radiator or similar) and then paint them with a very weak watered-down acrylic paint in appropriately stony/earthy colours. But I think ours looked fab just as they are.

I'm now off to put together the rest of the workshop - all the information on what fossils are, how they form and how we find them etc - but if Henry is anything to go by, making your own fossil is going to be the best bit!

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