CI Hand Molding

I asked Ernie, a Martin collector and a current ‘melt, mold production supervisor’ at the Lodge factory, about the age of the Martin No. 3 and he said:

“They made these from 1920-1950 [my Martin No. 3]. Some say the smoother the finish the older it is but I don’t believe that to always be true. Some of the old castings with rough finishes can be caused by wet sand. In making hand molds the sand was piled on the floor and the old squeezers were on wheels & rolled along the pile of sand using it up as they molded. This also allowed the molds to be carried off the squeezer & laid out on the pouring floor before the weights & jackets were put on. With all that said, most molders used facing sand on the surface of the pattern to get the smooth finish.”

“If the facing sand ran out & they were shoveling from a pile this would also cause a rougher finish. If the mold was not rammed good or bounced in the flask this would also cause a rougher finish. When the molders were paid piece work this would hurt quality because molders could short cut and make more molds per day which would result in them making more money.”

“Facing sand was made on the side with the normal molding sand. As you said it is much finer because it was mulled in a small Muller that sat on top of a wheel barrel. These were referred to as speed mullers.The molder could shovel a load in and mull it till he got the fine grain distribution of sand he needed. This sand was used on the surface of the pattern to get that smooth finish.
Molding sand is recycled & used over & over. The sand up against the casting surface is burnt when a mold is poured. This affects grain size so new sand is added back into the system to make up for that. Most foundries monitor the size of their sand thru testing.”
“In the old days new sand was added per experience and sight. Sand was made in batches by adding seacoal, bond, water, & a few other materials. The muller man could test each batch for wetness with a ruler in a quick compactability test & adjust as needed. This sand was hauled to the molding floor & laid out for the molders. Molders would take some of this sand & speed mull it to get finer grain sand to get that slick finish.”
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