Wisconsin in February is a problem for any liquid with a pour point above 50°F. Adhesives crystallize. Waxes solidify. Vegetable oils cloud. Glycerin gets sluggish. A customer who has shipped us a 40-tote load of slow-flowing product is, on a January morning, looking at a 40-tote load of solid product.
What we have built
A heated intake bay big enough to thaw four totes at a time. Insulated, sealed against drafts, and warmed to about 80°F by a propane unit heater. A 40-tote load thaws in roughly 36–48 hours.
For totes that need to come up to a specific temperature (sometimes the wash needs the product to be at certain viscosity before draining), we have a set of silicone band heaters that strap around the cage. They run about 1.4 kW each and bring a 275-gal tote of waxy product to 100°F in roughly 14 hours.
What does not work
Trying to thaw outdoors with an electric blanket. Trying to warm with an open propane torch on the cage. Trying to wait. All of these have been tried by customers; none of them work.
The honest commercial note
Winter intake of viscous product is more expensive than summer intake of the same product. We charge a winter surcharge of about $14 per tote for products with documented pour points above freezing. Customers know about the surcharge before they ship; it is in the contract.