PU cold-box cores bind sand with 0.4–1.2 wt% two-part phenolic urethane resin (Part 1 phenolic, Part 2 isocyanate) and cure with 0.05–0.15 wt% tertiary-amine catalyst carried in compressed air, per ASK Chemicals process data [S2].
Amine-process cold-box binders are widely used for cast resin-sand mixtures because the combined system delivers low overall cost, fast cycle times, and tight dimensional accuracy on cores for series iron and aluminum castings [S4]. Cold-box output runs roughly twice the productivity of the Croning shell process, and the no-heat tool requirement alone removes a large energy line item from coremaking economics [S2][S5].
Where the per-kg cost actually sits in 2026
For a 0.8 wt% binder addition on silica sand at roughly USD 1.55–1.85 per kg of finished core, the phenolic urethane resin component contributes approximately USD 0.80–1.50 per kg of core, assuming 2025–2026 phenolic urethane resin pricing in the USD 2.00–2.40 per kg range [S2]. The amine catalyst adds a much smaller slice: at 0.1 wt% addition on a typical DMA (dimethylethylamine) or TEA (triethylamine) basis, the amine cost is roughly USD 0.05–0.15 per kg of core, depending on whether the foundry runs recycled amine gas from a scrubber or fresh catalyst [S2][S8]. Together the two consumables sit in the USD 0.9–2.0 per kg-of-core band that most European high-volume iron foundries quoted during 2025–2026 process reviews, with the spread driven almost entirely by resin add-on, not amine price [S2].
For cost modeling, foundries should anchor the binder share to weight-percent of sand, not to a flat per-core figure, because a 0.4% thin-wall core and a 1.2% heavy-section core can differ by 3x on resin cost while amine consumption only doubles across the same range [S2]. The cold-box process is documented at over 60% of European sand-core production and on a similar trajectory worldwide, so the resin-amine cost band reported here is the de-facto benchmark rather than a specialty-process anomaly [S3].
Cost driver ranking: what moves the price per kg of core
Binder addition rate is the largest single lever, and it is set by sand fineness, core geometry, and required tensile strength, not by the binder supplier's list price [S2][S1]. A drop from 1.2% to 0.4% on sand cuts resin spend by roughly two-thirds on that line item, while amine consumption scales only from about 0.15% to 0.05% over the same range, so the catalyst line shows up as a much smaller savings line on the P&L [S2].
Catalyst chemistry is the second lever, and the swap from TEA to higher-reactivity DMPA (dimethyl-n-propylamine) or DMEA variants reduces amine consumption while shortening purge time, which compounds the savings through shorter cycle time and lower compressed-air cost [S5].
Sand-to-binder ratio is the third lever, and reclaim quality drives it directly: thermal or mechanical reclamation of cold-box sand allows higher reclaimed-sand fractions in the mix, which in turn lets the foundry hold lower binder addition for a given core strength because reclaimed grains carry less organic residue than fresh sand [S1][S7]. Cold-box binders are explicitly formulated for high reclamation compatibility, with used cold-box sand described as almost pH-neutral after proper mechanical or thermal treatment [S2].
Tooling material choice and gas-system design round out the cost picture: because cold-box tools can be wood, plastic, or metal, the no-heat requirement removes the natural-gas or bottle-gas line that drives shell-process economics (450–650°F heated tool per [S5]), and the amine-gas recycling loop on modern gassing heads pulls a non-trivial fraction of unreacted amine back for reuse [S5][S1]. The HA Solventless cold-box platform published in 2013 already demonstrated that proper solvent and additive selection can cut emissions and amine consumption simultaneously, a finding that still anchors 2026 binder procurement specs [S8].
Cold-box versus shell and hot-box: where the per-kg cost is lower
Shell process phenol-formaldehyde resin additions sit at 2–5 wt%, roughly 3–5x the cold-box range, and the heated metal tool consumes natural gas or bottled gas for every cycle, so the combined resin-plus-energy cost per kg of shell core runs well above cold-box even before counting higher HAP (hazardous air pollutant) handling overhead [S5]. Hot-box tools also run warm with similar resin penalties, leaving phenolic urethane amine-cured cold-box as the structural cost winner on ferrous and most non-ferrous volume cores [S1][S2].
For aluminum engine-block water jackets and oil-duct cores, the cold-box cost advantage widens further because cold-box cores exhibit high thermal stability and fast initial strength, which avoids the pre-coat baking step that hot-box and shell cores require to reach the same casting temperature tolerance [S2]. Foundries that have already invested in high-capacity cold-box core machines with amine recycling also amortize the per-kg amine line across more cores, which compresses the catalyst share below 5% of total consumable cost on a kg-of-core basis [S5][S3].
Total cost of ownership: what is missing from the headline price
Per-kg consumable cost understates the real bill because amine scrubbing, post-purge air treatment, and exhaust VOC (volatile organic compound) abatement are capital- and energy-intensive on a modern cold-box line. Modern gassing-system designs on equipment like the cold-box core machines used in series iron coremaking feed the amine through a controlled gas-supply and gassing-head loop, and the choice of purge time directly trades cycle time against amine mass remaining in the core [S3][S5].
Foundries that under-purge to save cycle time leave excess amine in the core, which reduces moisture resistance and downstream water-coating performance; foundries that over-purge burn compressed air and pull more amine into the scrubber, where the recovered stream either recycles back to the gassing head or gets destroyed in the exhaust train [S6][S1]. On a per-kg-of-core basis this trade-off is typically worth 0.5–2 seconds of cycle time, and on a 200-core-per-hour line the cycle-time impact alone can outweigh a 5% binder price move over a quarter [S3].
Reclamation and binder recovery is the other large TCO (total cost of ownership) lever not visible in the per-kg consumable figure. Cold-box sand at 0.4–1.2% binder addition is documented as highly reclaimable through both mechanical and thermal routes, and HA's three-platform binder range (Sigmacure, Biocure, Silcure) is explicitly designed around different reclamation and emission profiles, with Biocure alone delivering 30 years of plant-based solvent use and meaningful VOC and HAP reduction at the pouring and shakeout stages [S1][S7]. For a foundry doing realistic TCO modeling, the right figure to track is binder-cost-plus-sand-reclaim-cost-plus-amine-recovery-credit, not the kg-of-resin line alone.
Specification and standards context
Amine cold-box cores are produced under supplier-specific proprietary formulations rather than a single international standard, but the underlying process window is governed by the binder supplier's recommended addition range, the amine gassing time-purge profile on the cold-box core machine being used, and the binder compatibility with the specific water-based or solvent-based coating being applied [S2][S3]. The amine gassing stage uses high-pressure compressed air from the supply source to carry the catalyst through the core box, and the purge stage uses clean compressed air to displace residual amine through the vents before core ejection [S3].
Patented amine-process cold-box binder formulations filed in China (CN108714681B) confirm the current industry formulation space: phenolic resin, polyisocyanate, polyester polyol, aromatic hydrocarbon solvent, and a small acid-component package (including citric, oxalic, acetic, benzoic, or hydrochloric acid variants) to control reactivity and reduce heavy-metal content [S4]. These formulation choices are what allow modern amine-cured cores to keep amine consumption low while delivering high initial strength, fast bench life, and good water-coating stability [S2][S4].
How to use these numbers in a buying decision
The cheapest headline resin price is rarely the cheapest core price once reclaim credit, amine recycle credit, and cycle-time penalty are netted out [S1][S5].
For operations, the single highest-ROI (return on investment) change available in 2026 is the TEA-to-DMPA catalyst swap combined with amine-gas recycling on the existing gassing head, which is documented to cut amine mass per core while shortening purge time and improving workplace odor conditions [S5]. Pair that with a binder-addition audit against core tensile strength targets and most iron-foundry lines will land in the lower half of the USD 0.9–2.0 per kg-of-core range within one quarter [S2][S3]. For broader context on how raw-material pass-through and energy lines are structured in adjacent casting and equipment-purchasing decisions, see the Aluminum Ingot Pass-Through Clauses in Die Casting Part Pricing reference and the Aluminum Die Casting Part Cost Per Kg: Driver Breakdown walkthrough, both of which use the same per-kg cost-driver logic as cold-box coremaking.
For the relevant spec sheets and selection criteria, see hot box core machine, and cold chamber machine.