Core Pastes & Hot Shell Adhesives
In the No Bake or Air Set Process, molds/cores are produced using a resin bonded air setting sand. These molds/cores are allowed to harden under normal atmospheric conditions. Quite often these molds/cores are broken or are actually sectional cores and as such require Core Paste to join the pieces together. Water based, silica free products are available for this need. If a faster drying time is required, solvent based products are also available.
Core Paste , Hot Shell Adhesives
In the Shell or Hot Box Process, resin bonded sand or a sand/resin mix is placed on a heated metal pattern for a short period of time to form a partially hardened shell. The bulk of the sand mixture inside the shell is removed for further use and then the pattern and shell are then heated to further polymerize the sand/resin mix. The shell is then removed from the pattern. As with the No Bake Process, these shells are broken or are sectional cores and require an adhesive in order to piece them together. Hot Shell Adhesives containing a thermosetting resin are typically used for this. These Hot Shell Adhesives are generally applied to the hot shell cores and molds and typically utilize a liquid carrier that does not boil or dry out rapidly, allowing the operators sufficient time to position the pieces.