Exposing a package to a coloured dye solution under defined conditions and checking whether dye enters through a leak path.
Also called: blue dye test; methylene blue test; dye penetration; dye ingress.
What does a blue-dye blister test actually show?
The test looks for detectable dye entry after exposure to a dye solution under defined conditions. A blister procedure may include immersion, vacuum exposure and opening the pack for inspection. Visible entry is qualitative evidence from that test, not a direct gas leak-rate measurement.
Package immersion differs from testing an exposed seal edge. A useful test description identifies the specimen, dye exposure and reading method; “blue dye” alone leaves these unresolved.
Entry needs a suitable driving difference, a path through which dye can move and enough dye to be detected. Defect geometry, headspace, package mechanics, exposure and interpretation matter. Demonstrate the actual package/test combination rather than transferring conditions from a different container type.
For comparison, retain known-good and deliberately defective sample results and document how the inspection was read. An absence of visible dye without such context cannot establish a universal detection limit. Because dye exposure and opening change the sample, plan sample disposition separately from nondestructive test options.