The low-temperature applicability of Foundry Coating Binder is determined by its solvent system and molecular structure. More than 90% of commercially available Foundry Coating Binders adopt water-based systems designed for standard operating temperatures between 10°C and 35°C. They can be used under low-temperature conditions, but performance gradually deteriorates as temperature decreases, and complete failure occurs once the critical temperature threshold is reached. A small number of modified anti-freezing binders can adapt to low-temperature working environments and meet production requirements for outdoor workshops or uninsulated plants in winter.
Within the low-temperature range of 0°C to 10°C, the binder will not freeze and fail, yet its practical performance drops markedly. Water acts as the solvent for water-based Foundry Coating Binder. Low temperatures reduce molecular activity of water and slow the movement of polymer colloids, directly increasing binder viscosity and weakening fluidity. After mixing into coatings, inconsistent consistency and impaired suspension stability appear, easily triggering precipitation of powder materials and stratification featuring dilute upper layers and thick lower layers. Uniform spreading cannot be achieved during brushing or spraying, resulting in sagging, uneven thickness and missing coating areas. Meanwhile, low temperatures drastically slow down curing and drying speeds of the binder. Surface drying that takes half an hour at normal temperature may require 2 to 4 hours under low temperatures, greatly lowering operational efficiency.
When ambient temperature drops to 0°C or below, ordinary water-based Foundry Coating Binder will freeze. Volume expansion from frozen moisture thoroughly destroys the polymer crosslinking structure and colloidal stability of the binder. After thawing, the binder stratifies, flocculates and agglomerates, completely losing its bonding capacity. It can no longer bind refractory powder, and coatings formed after brushing tend to peel and pulverize, losing anti-metal-penetration functions entirely. This further induces casting defects such as surface peeling and sand drop-off. By contrast, alcohol-based and anti-freezing modified binders are supplemented with anti-freezing additives and modified resins to substantially lower freezing points. They can withstand temperatures ranging from -5°C to -15°C with generally stable fluidity and curing performance for normal construction.
Low-temperature operation brings multiple process challenges beyond performance degradation of Foundry Coating Binder itself. Slow curing under low temperatures leads to mold closing and pouring before coatings are fully dried. Residual moisture trapped inside coatings vaporizes under high temperatures and creates porosity and pinhole defects. Furthermore, coatings cured at low temperatures have insufficient crosslink density, reduced adhesion, hardness and high-temperature resistance. They tend to crack and peel during pouring and induce metal penetration defects.
Targeted process adjustments are therefore necessary for winter low-temperature production. For ordinary water-based Foundry Coating Binder, raw materials and construction ambient temperature should be maintained above 5°C. Preheat materials in advance and keep workshops enclosed for thermal insulation. For workshops without insulation facilities, switch to special low-temperature anti-freezing Foundry Coating Binder to eliminate risks of freezing failure and performance attenuation. This guarantees coating construction quality and casting forming quality under low-temperature working conditions, and stabilizes production efficiency and product qualification rates.
