Moisture Vapor
Barrier packaging uses specific polymer laminates or metallized substrates to prevent atmospheric humidity from degrading sensitive dry goods during long supply chain transit. Converting lines apply these protective coatings through extrusion or adhesive bonding methods onto virgin kraft paper or bleached folding boxboard. A converter must maintain strict coat weight tolerances because excessive sealant thickness causes thermal distortion during high speed vertical form fill seal operations.
Paperboard treated with polyethylene layers achieves exceptionally low water vapor transmission rates required for hygroscopic food powders and pharmaceutical tablets. Fibrous packaging materials without these engineered protective layers absorb ambient moisture rapidly, leading to structural softening and microbial spoilage within temperate storage environments.
Oxygen Transmission
Metallized films and specialty fluoropolymer coatings restrict gas permeation to protect sensitive contents from oxidative rancidity and flavor loss. Extrusion coaters deposit thin metallic layers onto flexible cellulose webs under high vacuum conditions to create dense molecular barriers against atmospheric gases. Packaging engineers measure oxygen transfer rates using controlled volumetric diffusion cells calibrated to standard temperature and relative humidity parameters.
Microscopic pinholes in the applied coating compromise the entire barrier assembly, allowing unwanted chemical reactions to degrade consumable products prematurely.
Regulatory Compliance
Food contact safety legislations dictate acceptable chemical migration limits for all packaging components that interface directly with consumable items. Analytical laboratories test finished converted laminates using solvent extraction methods to verify that residual volatile compounds remain well below prescribed legal thresholds. Brand owners specify these certified material grades to prevent unauthorized substance transfer from the outer substrate into sensitive medical formulations.
Paper mills supply complete compositional disclosure documents so converters can guarantee full compliance with regional packaging directives.
