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Taking your time.

Hi folks,

Next week I'm on holiday so it'll be two weeks till the next blog.  Partly because of that I thought that this week I'd look at some experiments and activities that take a bit longer from a few hours to several days.

Camera Obscura/Pinhole Camera

Making a pinhole camera where you can see a live picture projected onto a screen at the back, is relatively straightforward and can be done with a container and some tracing paper/grease proof paper as shown here or here's a version with a Pringles tube which uses the lid instead of tracing paper.  If you are feeling ambitious you can even turn your whole room into a camera with you inside it (this is usually known as a camera obscura).

If you want to capture the image you could just take a picture of the image with another camera, but if you'd like to have a go at developing your own photos you could try following these instructions from the Ri on how to develop your own photo negatives using photographic paper (you can buy this online) and relatively easy to find things like vitamin C tablets and mint tea (yes, really!).  Alternatively if you have a flatbed scanner, you can try this method (which I believe works better for longer exposures).

Cyanotypes/Sun Print Paper

For an even easier method of developing a picture you can use cyanotype paper usually sold as sun print paper.   This paper turns blue as it is exposed to light and you can create white 'shadows' by laying stuff on top of it and leaving it in the sunlight. Here is a beautiful image of some algae produced that way by Anna Atkins from the History of Science Museum collection.   In theory, you can also use it in pinhole cameras but it is tricky to produce a good image that way.  

Star Trails and astrophotography 

Stars appear to move in the sky over the course of the night (actually it is the Earth spinning that makes it look like they are moving),  Why not have a go at setting up your smartphone camera to record it?  This article shows you how you might do that and also has some good tips for taking great photos of constellations in the sky too.

Gardening and plant growing

In a previous blog I described how to make a grasshead which will grow fairly fast, but why not have a go at growing some plants.  Perhaps even something you can eat.  Here are some ideas for things to grow from the RHS.  You can also have a go at some science experiments with plants - this one looks a phototropism (plants moving towards the light).  Plants rely on capillary action to pull water up from their roots,  you can see this nicely by putting celery or flowers like carnations in coloured water.  

Crystal Growing

You may find it easiest just to buy a crystal growing kit for this, but you can just buy the ingredients separately and do your own experiments.  There is a nice borax crystal shape growing experiment here which works well but as mentioned it is difficult to buy borax in the UK nowadays (be careful as you often see borax substitute being sold as borax and it doesn't work the same way).  If you do buy some borax, have a go at making slime with it, it works really well. You could also have a go at creating rock candy with sugar crystals (you can even eat it afterwards).  For much faster crystal formation you could buy a rechargeable hand warmer (the kind with a metal disk in it that you click). These form crystals very quickly and are made of the same stuff used to flavour salt and vinegar crisps.  You can even have a go at creating the crystals at home.

Vinegar and Eggs 

Another experiment which takes a bit of time, but is definitely worth it is leaving an egg in vinegar. For a nice experiment that uses a range of different liquids see this video from the Ri.


Longer experiments from previous blogs




Brittle/Bendy Bones 

That's it for this week.  I'll be back in two weeks.  


Two kittens