Older converting still uses straight or lightly modified petroleum wax: wet waxing, dry waxing, and laminating. The same three layouts run when wax is replaced by a wax/polymer hot melt. Call 800-249-0337.
Wet waxing
Most of the wax stays on the surface. Shock-chill in a water quench or over chilled rolls to set it and add gloss. Typical path: unwind → molten bath → metering rods or rolls → quench. Household waxed paper, cereal and cookie wraps, bread and candy wraps, potato-chip bags, kraft car liners, frozen-food overwraps. Formed cups and tubs are spray- or dip-waxed after they are made, then chilled.
Dry waxing
Wax is driven into the fibers; almost no surface film. No quench; hot rolls help soak-in. Lower-melt paraffin is fine except some greaseproofs that want high-melt paraffin. Cone cups, butcher and butter wraps, locker paper, tissue, box liners, building paper, crepe, medium and linerboard.
Laminating
One web through a wax bath, nipped to a dry web, then heat rolls. Refined microcrystalline is the usual laminant; asphalt in some processes; paraffin rarely. Paper/paper, foil/board, kraft/kraft, foil/kraft. Bond can exceed the plies. Cereal boxes, sugar and fruit-ade bags, soap and gum wraps, building papers.
Cups and corrugated
Hard-sized bleached sulphite, slit, print, form, glue, then flood-and-spin (~180–185 °F) or spray (~200 °F, preheat cups). Dry-waxed cups go through a heat chamber before cool; wet-waxed go straight to cool. Kill latent heat or nested cups block. Typical: 145 °F fully refined paraffin, or a higher-melt blend for satin and dispensing.
Corrugated for produce, iced fish, and poultry needs wet stacking strength. Roll or curtain the combined board; or roll-coat medium/liners on the corrugator then curtain. Dip saturation (batch baskets or a conveyor through a tank and oven) or cascade: blanks on edge under wax fountains, air knives, cool. Pick-up is wax temperature, dip time, drain temperature and time, viscosity. Too hot/long = brittle; too cold = edge build and stack block. Cascade sat typically 215–230 °F at 3–4 fpm; surface coat 185–200 °F at 8–20 fpm. Field-pack: dry wax; ice-pack or hydro-cool: cascade then curtain. Well-sized board can wet-wax for moderate damp service without a curtain.
Curtain coating
Moisture/grease holdout, scuff protection, looks. Produce and poultry are the volume. Usually saturate first, then curtain. Pressure-head (orifice) vs weir (gravity overflow): pressure head claims higher speed and more even weight; weir claims higher viscosity and low weight at low speed. Trend has been toward pressure heads.
Folding cartons
Butter, bacon, ice cream, frozen food. Hot-melt wax blends more than lacquer. Pattern/gravure waxers coat only where needed so flaps can still glue. Early pattern units wanted under ~100 cps at 300 °F; later reverse-roll blank coaters reached ~3,000 cps, then ~10,000–16,000 cps at 250–300 °F for heat seal, hot tack, and barrier. Barrier coats about ½–1 mil (~5 lb/MSF per side at 1 mil); count surface plus soak-in. Target WVTR on the sheet: about 0.3 g/100 in²/24 h/mil flat at 100 °F, 90–95% RH; about 0.6 creased. Raising EVA in the blend improves crease WVTR, grease, score flex, and block; dewaxability stays poor.
Wrap-around on light board: grooved rolls, silicone blankets, or hotter (thinner) melt. Blush: more reheat, colder quench. Poor finish: burnisher temp or gap. Warp: damp board or coat too thin. Grease leaks: weight or pinholes (damp board). Block: stack before cool. Poor adhesion: moisture; hotter melt if you cannot pre-condition. Slip and hardness need 24–48 h. Light 10–14 pt board is harder to run.
Hot melt adhesives vs coatings
A coating is mostly wax plus some polymer and resin. A hot melt adhesive is mostly polymer, with resin for wet-out and tack and wax for viscosity, cost, and set. EVA is the usual polymer. Microcrystalline helps adhesion; paraffin helps barrier. High-melt wax helps peel. Application: cartridge guns through laminators to packaging-line modules.
Outside converting: investment-casting (“lost wax”), candles (fully refined paraffin and stearic; some formulas replace 15–20% stearic with 0.5–1% low-viscosity EVA), crayons (montan, candelilla, petroleum wax, hydrogenated oils, stearic or PE), carbon-paper inks (pigment carrier and surface skin). Also undercoating, cable, cheese coats, cosmetics, dental waxes, matches, textile waterproofing, wallboard.
Related: barrier coatings, hot melt, packaging, folding carton types, corrugated washboarding.