Lab Notes 11/25/14

9:57am, Columbia Chem Lab
Outside temperature: 61 degrees
Subject: To make stucco for molding

This morning we are experimenting with the tragacanth gum experiment.

We sifted the rye flour finely as best we could using the equiptment available in the lab (a makeshift strainer from a cheesecloth over a beaker. I am not sure how effective this was, as most of the flour seemed to pass through.

Jef got sticky stuff stuck to his hands from someone’s measuring spoons they had left in the sink while he was trying to clean them. We paused while he endeavored to wash it off, a process that was mostly in vain. Better cleaning procedures might be universally helpful.

Added 250ml of water to the mixing bowl to begin making the gum. Jef added apped t-gum by tapping it into the water in 10ml increments, using a knife as our stirring implement because that was what we could find. Jef observed that agitating the mixture worked better to combine it than just stirring. This would definitely be easier to stir with a fork or a whisk.As with his previous trial of this experiment, the mixture coagulated swiftly into a viscous substance. Emily took over stiring until 40 mls were added.

Jef now adds 100 ml of flour to the t-gum mixture. Because he is not getting the fine consistence (like a dough) that the recipe describes, he emptied the mixture from the bowl and began mixing it with a paint scraper on a marble slab.

He added an additional 100ml of the rye flour and stirred on the slab. Jef observed that the mixture has a “very nice” consistency, which he attributed to our sifting the flour this time. Jef adds an additional 50ml of flour. The mixture still does not have the consistence described in the recipe of being able to be stretched without breaking. Jef creates a mixture of ¼ tsp more t-gum and 30ml of water. Jef ads an additional ¼ tsp more.

Now Jef spreads the mixture out on the marble slab and we brush the mixture with linseed oil “to make it more detachable”. Emily observes that this is like adding butter to cookies so you don’t have to grease the cookie sheet. Jef brushes the mixture with linseed oil three times total. We started with 50ml of the oil and after the three brushes 20 were remaining. Thus we used 30ml total of linseed oil, or approximately 10ml per brushing.

We combined that with the mixture, and then transferred the mixture to the wooden board on which we planned to mould the stucco. We began using metal and plastic tools (putty knives and similar) to mold the stucco into shapes. Emily made an attempt at a Tudor rose, and Jef was working off an image he found of a basic example of Italian moulding.

We observed that working with the metal tools was much easier than the plastic (the stucco stuck to the plastic but not the metal), and brushing the area you are working with with a thin layer of the linseed oil really helps separate the stucco from your tool and make it easier and smoother to mould.