Understand the surface question
Liquid penetrant can reveal discontinuities open to a clean, non-porous surface. This makes it useful for selected stainless steel and aluminium welds and components where magnetic particle inspection may not suit the material. It cannot reveal an enclosed internal flaw with no opening to the examined surface.
The dye penetrant testing service should be scoped around the material, surface finish and suspected damage. State whether the objective is fabrication examination, investigation of an observed feature or checking a defined repair. Identify the actual surfaces, not just the assembly name.
Prepare without closing the opening
Oil, grease, water and residues can block a fine surface opening. Paint or other impermeable coatings normally prevent penetrant from reaching the metal surface. Cleaning must leave the area suitably dry and compatible with the procedure before penetrant is applied.
Mechanical preparation can create a different problem: grinding, blasting or polishing may smear metal over an opening, particularly on softer materials. Ask for an agreed preparation method rather than treating a bright surface as proof of suitability. Preserve photographs of a suspected flaw before changing its appearance.
Match consumables and conditions to the job
Consumable compatibility matters for the component and service environment. Some stainless steel applications impose contaminant controls; aluminium assemblies may also have cleaning and chemical restrictions. Supply the relevant specification so the inspector can select products and processes accordingly, without assuming one kit is suitable for every alloy.
Penetrant dwell, removal, developer application, temperature and examination lighting follow the selected procedure. Too much removal may wash penetrant out of an opening; insufficient removal may leave a background that obscures indications. Do not prescribe universal dwell times from a generic online checklist.
Read indications in context
An indication shows where penetrant has emerged, not necessarily the exact physical size or depth of a discontinuity. Surface roughness, thread roots, edges and trapped residues may produce responses needing interpretation. A linear or rounded appearance is useful descriptive evidence, but acceptability still depends on the nominated criteria.
Record location, shape, dimensions as reported, surface condition and any uncertainty. A porous or heavily roughened surface can make interpretation difficult. Where a finding requires confirmation or internal assessment, discuss a suitable complementary examination rather than inferring depth from the visible stain.
Close out the examination and repair record
Plan post-cleaning and protection of the surface after testing. If a repair follows, preserve the original indication and map the repair location so repeat testing can be connected to the same component. Changes in preparation or technique should remain visible in the follow-up record.
A report saying no relevant indications were found applies to the examined area and stated conditions. It does not establish that an aluminium fabrication or stainless pressure component has no internal defects or is ready for operation. The responsible reviewer needs the scope, limitations and any additional evidence required for that decision.