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Extreme Paper Mache
Whereas with small scale papier mache (papier-mâché) model making and other artistic paper craft, fine quality and small amounts of glue are used, the technology of Extreme Paper Mache / paper mashy has a somewhat different approach.
The idea started here with plans to build an astronomy dome. Astronomy domes, being round shaped, aren't readily made out of bricks, planks of wood, and other conventional rectangular shaped building materials. Also, using recycled old newspapers had the attractive advantage that the building materials could potentially be free of charge. This was a major consideration.
Although a lot of people thought it would be a good idea to add glue of some sort, this was actually not required. Paper, when mashed up and re-formed to dry, holds together quite solidly without any added glue. Admittedly glue would have made the material stronger, but as the plan was to use a ton of paper, the glue component would have required a lot of glue, and it could have been expensive. Flour was the favourite suggested bonding agent mentioned by most helpful people, but it was declined. The trouble with flour is that as well as it costing actual money, it might also go mouldy. Moldiness is a commonly encountered hazard in the construction of paper-mashy buildings and large scale structure!
Newspaper dunked in water will disintegrate naturally, but it's possible to give it some help. Small scale projects have been known to use a food blender, but for the astronomy dome a large washing machine was used. Nearer the size of a cement mixer, the huge drum with a slow moving agitator could easily mash up large numbers of newspapers in water and generate a pulp which was of the consistency of porridge. Separating the sheets and dropping them in the tub torn-up helped to stop them sticking together. A variety of newsprint publications were used, and recycled into building materials regardless of the quality of the authorship that went into their initial creation. No disrespect was intended in the recycling of the newspapers, and it was no worse a fate than newspaper being used for the budgerigar cage or for wrapping fish and chips. Incidentally, batches of papier mache made from the Financial Times retained a curious slightly pink quality in the final mix.
Having created soggy pulp, the next step was to turn this into an edifice. As well as the obvious advantage of paper mache being inexpensive/free, there is also the flexibility of form, so the material could be molded to any shape. For the dome, a dome-shaped former was required. For the full-scale dome, estimated diameter 24ft, estimated weight 1 ton, the idea was to use a meteorological balloon (to get an idea what these look like, reference The Prisoner). For the prototype, a 6ft diameter aluminium Van der Graaf hemisphere was used. There just happened to be one around handy.
The first thing to go on the mold/former was LARD. Any type of inexpensive grease would have done; it didn't need to be animal fat. (The purpose of the grease was to allow the dome to be separated from the mold when completed).
Next, pieces of wet newspaper were applied in layers to form a lining. Then, the soggy wet pulp of mashed newspaper was applied over the top. It was evenly applied, and many washing machine loads of paper applied. In all about two hundred newspapers were required for the 6ft dome.
The usual criticism of making of paper mache dome like this is that it is alleged to be impossible to dry outdoors in the UK. This might seem logical, as it tends to rain quite a lot and the British Weather is notorious. But in practice it was found that the dome could be left outdoors and would dry out on average. In sunshine in summer, on sunny days the dome would dry out, and even when there was rain, it would not soak the paper dome enough to undo the drying that had been done during the dry days. Sun, even in the UK, has a remarkable ability to dry out stuff left out in the air, including paper mache. The other advantage of drying the dome outdoors was that the sun bleached the drying paper mashy so it did not go mouldy. This also saved money on fungicide.
Something else which helped the shell of the dome to set properly was that it was patted and compressed every now and then as it dried out, giving it an additional strength.
At some point, on a dry day, the dome was painted with waterproof paint. After that it was a weatherproof dome. Even steel structures aren't weatherproof if unpainted! Some people would question the choice of paint, but it's a matter of taste. You don't have to use Artex if you'd prefer something different.
Although 6ft diameter is too small to use as a practical observatory to keep a telescope in, it was a proof of concept. To keep the design in keeping with the intended full-size dome, a carefully cut doorway had to be cut. Surprisingly tough stuff. But at least the door was the right curved shape. Again, more paint.
The test prototype paper mache dome was on show for many months and was shown off at an astronomy conference. Astronomers would rather not just believe something and would rather see it themselves, whether through a telescope or otherwise.
Making a building out of paper? Yes, it's true!