What is Choke and Spread (Trapping)?
Technical definition, shop floor implications, and pricing strategies for commercial apparel decorators.
Pre-press graphic adjustments that expand (spread) or contract (choke) adjacent color boundaries to prevent white gaps caused by press vibration or fabric stretch.
Deep Dive & Practical Application
When separating artwork for multi-color textile printing, human hair-width registration shifts are inevitable due to fabric elasticity, pallet heat, and mechanical press tolerances.
A "choke" reduces the outer perimeter of a white underbase by 0.5 to 1.5 points (0.007"–0.02") so the top colors completely cover it without white peeking out around the borders.
A "spread" slightly expands a lighter top color underneath an adjacent dark outline to eliminate unintended pinholes of unprinted fabric.
Shop Floor & Profitability Impact
Accurate choking in pre-press eliminates hours of on-press alignment tweaking and prevents misprinted scrap on tight-registration orders.
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