Flower Pot Vulcanizer on Stand.
A chemical or round stemmed thermometer is arranged to go through the aperture in the upturned bottom of the pot. This may be hung from a support or it may be secured by passing through a hole in a cork or block of wood. Its bulb should be near the part of the chamber to be occupied by the mould or press.
The press with the article to be cured is placed upon the inner plate. The temperature is maintained at the proper point by regulating the heat, and all the conditions for excellent work are supplied. The disposition of the apparatus is shown in the cuts.
Interior of Flower Pot Vulcanizer.
Another arrangement equally simple is given in the next [cut]. An iron kettle has a layer of type metal or lead poured an inch thick cast within it upon its bottom. A thermometer passing through a hole in the cover enters a cup of glycerine that stands upon the bottom. This gives the temperature.
The object of having a thick or a double bottom is to prevent excessive radiation of heat from any one part. The essential condition for good operation is to maintain an even temperature throughout the chamber.
Fish Kettle Vulcanizer.
The thermometer is not an absolute necessity. By removing the press from time to time and inspecting the overflow of india rubber the progress of the operation can be watched. An extra piece of india rubber may be placed on a piece of wood by the side of or upon the wooden portion of the press, and its condition can be taken as the criterion. Pressure with the point of a knife will tell the vulcanizing point.