How to approve ceramic glaze and decoration
Approve each glaze and decoration variant on finished, fired production trials. Keep physical appearance boundaries, mark decoration positions and refer changed materials or firing processes for food-contact assessment before release. Coordinate the factory trials and approval records with Cambridge China Bridge.
Approve fired pieces from the production process
Ask the factory to trial each proposed body, glaze and decoration combination using the intended bulk materials, application method and production kiln. Inspect finished pieces after all glaze and decoration firings. A colour tile, digital artwork or unfinished sample should support the brief, rather than serve as approval of the finished tableware.
Request pieces from different kiln positions and trial runs, with records identifying the materials and firing conditions. Compare plates, bowls and mugs together as a range. Use bulk sample control for the general approval workflow; record ceramic combinations separately so a pleasing trial cannot silently authorise another recipe.
Define the acceptable appearance range
Retain labelled physical samples showing the target appearance and the acceptable extremes. Describe shade, gloss, speckling, mottling, glaze pooling and coverage at edges. View dry pieces under agreed lighting against the same background, both individually and as a place setting. Photographs help record decisions but should not replace physical comparisons.
Separate intended variation from defects. State how inspectors should treat pinholes, bare patches, glaze runs, crazing, rough rims and decoration blemishes. Hold cracks, sharp surfaces and suspect food-contact finishes for review rather than accepting them as rustic character. Define whether noticeably different shades may be packed together.
Fix decoration placement on the actual shape
Mark the decoration on drawings and fired samples using repeatable reference points: the handle, rim, foot and centre of the eating surface. Specify orientation, position, coverage, border continuity and where a wraparound pattern joins. Identify areas intended to remain undecorated, including drinking edges and food-contact surfaces where relevant to the design.
Check the artwork on every shape, including curved walls and handles. Agree how distortion, registration, blurred edges, missing print and overlap will be judged. Record whether decoration is beneath, within or above the glaze and whether it receives a separate firing. Use factory artwork approval for artwork versions and sign-off.
Refer changes for food-contact assessment
Food-contact materials must be safe for their intended use. Appearance approval cannot establish that safety. Before approving a changed ceramic body, glaze, pigment, decal, metallic decoration or coating, send the change details to the laboratory or food-contact adviser. Also flag changed suppliers, decoration coverage, firing conditions and proposed rework.
Provide the previous and proposed material specifications, finished trial identities, existing reports, decoration locations and intended food, temperature and reuse conditions. Ask the assessor to explain which variants the evidence covers and which need further assessment or testing. Do not assume a matching colour means matching materials. Our food-contact guide covers the wider documentation brief.
Release only the recorded combination
Keep an approval record linking each variant to its fired samples, appearance boundaries, placement drawing, material specifications, process record and food-contact assessment outcome. Distinguish appearance acceptance, assessment still pending and release for production. A request to lighten a glaze or move a decal should reopen the affected approval before the factory proceeds.
Give the inspector the approved records and require production pieces to be compared with the retained boundaries. Isolate unexplained differences while the factory identifies the cause. Cambridge China Bridge’s own staff in China can coordinate trial samples and factory checks, with the buyer recording the final approval and any outstanding conditions.
Frequently asked questions
Can I approve ceramic glaze from photographs?
Use photographs to record comments, but approve fired physical pieces under agreed lighting. Keep samples showing the acceptable appearance range.
How much glaze variation should I accept?
Agree physical boundary samples for shade, gloss and pattern variation. Define defects separately and decide whether different acceptable shades can share a pack.
Can the factory move a decal after approval?
Ask for a revised placement drawing and fired trial. Refer changes in coverage or contact location to the food-contact assessor before release.
Does an existing report cover a new glaze colour?
Do not assume so. Give the assessor the changed formulation, process and intended use, and ask for a written coverage decision or further testing plan.