• Chemistry 09.09.2008 No Comments

    In my entry about the slime I mentioned fluorescein as dye. Today I am going to explain how I made it.

    I had some phthalic anhydride and resocinol in an old chemistry set but the resorcinol was quite dirty so I got some new at the pharmacy.

    Most synthesis instructions recommend zincchloride as catalyst but some drops of sulfuric acid work as well. (Sulfuric acid and zincchloride are both hydrophile, which is the needed effect).

    Fluorescein drop in water

    Fluorescein drop in water

    15g phtalic anhydride an 22g resorcinol are ground to a fine powder and placed in a test-tube and heated. I used an alcohol burner but i recommend a hot air gun.

    When the powder melts and turns into a thick, red, honeylike substance stop heating and let it cool down.

    The fluorescein can then be dissolved in a small amount of water resulting in a dark red/brown solution.

    One-two drops of this solution are enough to colour 500ml of water to a bright green.

    The best results are achieved when the coloured water is viewed in sunlight.

    A more detailed synthesis manual can be found at LambdaSyn.

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  • Chemistry 08.09.2008 No Comments

    Polymers are always fun. Especially when they are slimy.

    A great polymer gel can be made from Polyvinylalcohol and Borax (Disodium tetraborate).

    Just prepare a 4% solution of Polyvinylalcohol (i used the one with a molecular weight of 72000) and a 4% solution of disodium tetraborate.

    The PVA best dissolves under constant agitation and slight heating. Let it stir until the solution is clear and has no chunks left in it.

    Then add 2 parts of the boraxsolution to 10 parts PVA-solution and stir until the consistency gets slimy.

    PVA Slime coloured with fluorescein

    PVA Slime coloured with fluorescein

    If you want to color the slime, add the color to the PVA prior to adding the borax. A few drops of fluoresceinsolution give it a nice, shining green and quite some resemblance to Flubber.

    The slime quickly dries out when stored open, so it is best keept in a glas jar or in a plastic bag. This also delays the growth of mould in/on the slime.

    I have not yet tested the effect of preservative agents on the moldering.

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