It is prepared using unsized cotton rag paper (as is vulcanized fibre) and mineral acid.
[10] The key patents for the development of leatheroid were: These patents centered on using mineral acids (sulfuric and hydrochloric) to produce the high level of bonding for parchmentized paper and leatheroid as compared to using zinc chloride to produce vulcanized fibre.
However the use of this process to produce the highly bonded fibre board known as leatheroid had problems to be surmounted.
Using the cutdown machine to build up multiple layers of paper to various board weights entailed the problem of how to keep the acid from destroying the cellulose chains.
The key to the using the parchmentizing process for paper in the production of paperboard seems to center around using other chemical agents in the parchmentizing acid solution to retard or delay the destruction of the cellulose chains until such time as the acid is washed out or neutralized.
Other organic matters that may substitute for dextrin mentioned in 198382 were crude petroleum, blood, albumen, and paper and pulp.
Another technique used to retard or delay the action of the parchmentizing acid solution was to keep the reaction cold.
The importance of keeping the reaction cold was so important that leatheroid manufacturing in Kennebunk was suspended every summer until 1889 when the Leatheroid Manufacturing Company dug a well that provided a source of cold water year round as an alternative to using Mousam River water.