How to agree visual defect limits with a factory
Agree a written viewing method and physical samples showing the acceptable boundary and rejected appearance. Specify distance, lighting, viewing time and which surfaces matter, then have the factory and inspector trial the same method before production. Cambridge China Bridge can help coordinate this with its staff in China.
Define appearance by surface
Mark the product drawing or photographs to distinguish surfaces seen during normal use, surfaces exposed during handling and concealed areas. Give each area its own appearance criteria. A scratch on the display face may deserve a different decision from the same scratch underneath. Describe scratches, dents, coating marks, colour variation and uneven texture separately.
Add an appearance inspection sheet to your product specification. For each defect, record its location, extent, visibility and acceptance boundary. Avoid instructions such as “good finish” or “no obvious defects”, which leave the inspector to invent the test.
Fix viewing distance and lighting
Try the viewing method on actual products before choosing the distance. Record the distance from the observer’s eyes to the surface, the product position, viewing angles, background and whether rotation is allowed. Use a marked bench position or spacer to reproduce it. Specify whether viewing is unaided or uses magnification.
Record the lamp type, its position and the light level at the inspected surface. HSE guidance explains that a surface’s apparent colour can change with the light source or daylight conditions. Compare colour samples and products side by side under the agreed light. If angled light is needed to reveal finish defects, include that step explicitly rather than letting inspectors introduce it during a disagreement.
Set inspection time and handling
Agree a viewing period for each surface or a complete viewing sequence. Trial it with acceptable, borderline and rejected pieces, then write the chosen duration into the sheet. Say when timing starts and whether unpacking, cleaning, turning the product and checking a suspected mark are included. Do not let a quick glance and a prolonged search become competing acceptance methods.
Specify whether protective film is removed, how dust is cleared and whether the product is checked assembled or loose. Keep appearance assessment separate from checks for cracks, sharp edges or functional damage. Refer concerns about safety or function for separate assessment rather than approving them as cosmetic variation.
Keep physical boundary samples
An ideal approved sample shows the target finish but may not show the rejection boundary. Ask the factory to provide actual pieces illustrating the worst acceptable appearance and clearly unacceptable appearance for each relevant defect and surface. For natural variation, retain examples spanning the accepted range. Mark the defect location without covering it.
Label each piece with its defect description, surface, decision, approval date and specification revision. Keep matching reference sets with the factory and buyer or inspector, protected from fading, wear and damage. Use photographs as an index, not the sole colour or gloss reference. Our bulk production guide covers retaining the approved production sample.
Trial the decisions before production
Ask the factory’s quality staff and your inspector to assess the same trial pieces independently under the written conditions, without seeing the expected decisions. Compare results. Where they disagree, clarify the wording, replace ambiguous examples or adjust the viewing method, then repeat the exercise. Obtain written acknowledgement of the completed sheet and reference set before production.
The appearance sheet decides how an inspected piece is classified; the agreed sampling plan decides whether the batch passes. Use quality inspection explained for batch acceptance. Require the report to identify the viewing conditions, reference revision and disputed pieces. If you accept a deviation for a particular batch, record that separately using the cosmetic defect approval guide.
Frequently asked questions
What viewing distance should I use for defects?
Trial a distance suited to how the product is viewed in use. Record it with the viewing angles and surface position, then check that the factory and inspector can reproduce the same decisions.
How long should a visual inspection take?
Agree a duration after trialling the viewing sequence on real pieces. State whether it applies to each surface or the whole product, and how suspected marks are checked.
Can photos define acceptable scratches?
Use photos to locate and describe scratches, supported by physical boundary samples. Screen settings, reflections and camera processing can make photographs an unreliable sole acceptance reference.
Does AQL define acceptable appearance?
Agree what counts as a defect through the appearance sheet and boundary samples. The sampling plan then applies your agreed batch acceptance limits to the inspection results.