When procurement teams place large orders for porcelain makings, a handful of small process issues can become expensive headaches. As a ceramic mug manufacturer, Кедали sees the same root causes repeatedly — and we know they’re controllable.
The production of ceramic mugs typically involves five key stages (raw materials → molding → drying → glazing → firing). As a professional ceramic mug manufacturer, I will list common defects in each stage, explain their causes, and outline the preventative measures a reliable ceramic mug manufacturer should take.
Raw Materials: The Foundation of Quality
Common defects: black spots, iron specks, pinholes in glaze, and color inconsistency.
Why it happens: impurities in clay or glaze batches, poor particle size control, or inconsistent raw-material batching cause visible inclusions and gas-release problems during firing. A common problem in Chinese ceramic mug factories is the fluctuation in iron content across different batches of imported kaolin clay, which can easily lead to black spots or iron stains.
Prevention/factory controls:
- Material screening — magnetic separation and sieving of raw clay and frit to remove metal contaminants.
- Batch records — fixed recipes with batch numbers for clay and glaze, so every lot is traceable.
- Laboratory checks — regular chemical and particle-size tests, water-absorption tests for body, and pH/viscosity checks for glaze slips.
- Supplier qualification — approved vendor lists and incoming QC for all raw inputs.
Buyer tip: ask the ceramic mug factory for recent raw-material test reports and a sample of the retained input batch used for your production run.
Forming: Consistent Shaping and Handle Attachment
Common defects: warpage, uneven walls, handle cracks or detachment, and dimensional drift.
Why it happens: uneven moisture content, inconsistent pressure during pressing/throwing, or poor handle-attachment technique lead to shrinkage mismatch and mechanical stress.
Prevention/factory controls:
- Moisture control — measure and control clay slump and water content before forming.
- Tooling maintenance — calibrated molds and regular tool replacement to maintain dimensional tolerances.
- Standardized handle join process — controlled slip ratio, surface scoring, and mechanical compression to ensure a homogeneous joint.
- In-process gauging — dimensional checks (rim diameter, wall thickness) at set intervals on the line.
Buyer tip: Mugs are mostly manufactured using pressure molding or slip casting processes. Handle attachment is a high-risk step, and it’s crucial to ensure there are no air bubbles or stress concentrations at the joint. High-speed production lines are prone to dimensional variations, so it’s recommended to perform multiple gauge checks during each shift.
Drying: Slow, Even Moisture Removal
Common defects: drying cracks, rim ovality, base warp, and hairline fractures at handles.
Why it happens: rapid or uneven drying creates internal stresses; differing geometry (e.g., handle vs. body) dries at different rates and tears the joint.
Prevention/factory controls:
- Controlled drying rooms — setpoints for temperature, humidity, and airflow; staged drying schedules for different shapes.
- Rack and fixture design — support mugs to minimize distortion, avoid point loading, and ensure airflow around thin sections.
- Drying profiles by SKU — some shapes need longer low-temperature stages; this must be standardized and logged.
- Monitoring and alarms — sensors to flag deviations in real time.
Buyer tip: Insist on documented drying profiles and ask for historical defect rates related to drying for similar SKUs.
Glazing: Surface Finish and Compatibility
Common defects: crawling (bare spots), pinholes, orange peel texture, runs or sags, and color drift.
Why it happens: surface contamination, wrong glaze viscosity, improper spray or dip parameters, or a glaze-body mismatch in thermal behavior.
Prevention/factory controls:
- Surface preparation — cleaning and de-dusting before glazing; controlled handling to avoid oils from hands.
- Glaze recipe control — viscosity, solids content, and particle size controlled in batch records; pH and specific gravity checks.
- Application standardization — set gun distance, pressure, number of passes, and conveyor speed for automated spray; consistent dip times for dipping.
- CTE matching — test glaze and body for compatible Coefficients of Thermal Expansion to reduce crazing or crawling risk.
Buyer tip: Require the ceramic mug factory to provide a glaze compatibility certificate and sample color boards from the exact production batch.
Firing: the Kiln Profile That Makes or Breaks Product Quality
Common defects: crazing, blisters/pinholes, underfired bodies (soft, high absorption), overfired slump, shade variation.
Why it happens: incorrect temperature ramps, uneven kiln zones, insufficient soak times, or inadequate venting let gases escape improperly.
Prevention/factory controls:
- Kiln curve control — logged ramp-soak-cool profiles per SKU with PID control and redundancy.
- Zonal temperature monitoring — multiple thermocouples across the kiln and regular calibration.
- Load planning — uniform loading patterns and appropriate setters to maintain shape and airflow.
- Soak and vent stages — designed to remove chemically bound water and volatiles before glaze maturation.
- Post-fire testing — water absorption, modulus/stability checks, and visual inspection against golden samples.
Buyer tip: ask for kiln logs for your production batches and third-party test reports (water absorption, thermal shock) for representative samples. Thermal shock testing (boiling water to cold water) is a standard procedure for verifying the stability of finished products.
Integrating Controls into Procurement: What Buyers Should Require
To reduce risk before the first container sails, add these requirements to your RFQ and PO:
- Golden sample approval: signed, retained at the factory, and used as production reference.
- Material & test documentation: raw-material certificates, glaze migration tests, water absorption, and kiln logs.
- Process records: drying profiles, glaze application parameters, and equipment calibration records.
- QA gates: defined in-line checks, pre-shipment AQL, and batch traceability.
- Packaging & transit validation: engineered inserts, ISTA/drop-test evidence, and maximum acceptable breakage rate.
A reputable ceramic mug manufacturer will already follow these practices; if a supplier hesitates to share records, treat that as a red flag.
Conclusion — Defects Are Preventable, Not Inevitable
Most failures in high-volume керамическая кружка production trace back to one of the five production stages outlined above. The difference between a factory that produces occasional nice-looking samples and one that reliably ships millions of good units is discipline: standardized recipes, logged process controls, in-line inspection, and documented testing. As a buyer, demand those controls.
О Кедали
Kedali is a professional ceramic mug manufacturer specializing in bulk production for brands, wholesalers, and promotional product buyers. With a standardized workflow covering raw material preparation, forming, controlled drying, glazing, and kiln firing, Kedali delivers stable quality and repeatable output across large-volume orders.
Kedali’s ceramic mug factory supports custom ceramic mug solutions, including mug shapes, capacities, handle styles, glaze colors, logo printing, and packaging solutions to match different retail or gifting programs.
Backed by disciplined process control and batch-based inspection, Kedali helps B2B customers reduce defect risk, protect delivery schedules, and scale supply confidently from sample approval to full container shipments.
