GB/T 3301-2023Test method for determination of specification allowance and size of defects of domestic ceramic ware (English PDF)

Foreword

This document was issued on 23 May 2023 by the State Administration for Market Regulation; Standardization Administration of the PRC and takes effect on 1 December 2023.

It is a GB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

1 Scope

GB/T 3301-2023 covers how the specification errors and the visible defects of domestic ceramic ware are measured — the tableware trade, where a plate or a cup is accepted or rejected on figures that have to mean the same thing in the factory and at the buyer's inspection bench. The samples clause is one line: clean, undamaged ware. The specification-error clause then works through the individual measurements, starting with volume error and the flat glass plate, larger than the piece itself, used in determining it, and going on to rim diameter error, height error, weight error and maximum dimensional error. The defect-size clause covers how a defect is measured and with what — a steel rule graduated in half-millimetres, a vernier caliper graduated in tenths of a millimetre — and the test report closes the document. Ceramic ware moves in the kiln by an amount that varies with body, glaze and position in the firing, so no two pieces come out identical; the entire commercial argument is over how much variation is allowed and how it gets measured. Terms follow GB/T 5000. It is used by tableware manufacturers and their quality departments, importers writing acceptance clauses into orders, and the testing bodies that arbitrate a rejected shipment.

This document describes the measurement method of specification errors (including

volume error, rim diameter error, height error, weight error, maximum dimensional error,

etc.) and defect sizes of domestic ceramic ware.

This document is applicable to the determination of specification errors and defect sizes

of domestic ceramic ware.

2 Normative references

The following documents contain the provisions which, through normative reference in

this document, constitute the essential provisions of this document. For the dated

referenced documents, only the versions with the indicated dates are applicable to this

document; for the undated referenced documents, only the latest version (including all

the amendments) is applicable to this document.

GB/T 5000 Terminology for domestic ceramics

3 Terms and definitions

The terms and definitions defined in GB/T 5000 and the following apply to this

document.

3.1 standard volume

The volume indicated on the product.

3.2 standard diameter

The diameter indicated on the product.

3.3 standard height

The height indicated on the product.

3.4 standard weight

The weight indicated on the product.

3.5 standard maximum size

The maximum size indicated on the product.

4 Samples

Clean and undamaged domestic ceramic ware.

5 Determination method of specification errors

5.1 Determination of volume error

5.1.1 Instruments and equipment

5.1.1.1 Glass flat plate: The size shall be larger than the maximum size of the product

being tested. The flatness is checked with a steel ruler, and there shall be no obvious

gap between the glass flat plate and the steel ruler.

5.1.1.2 Measuring cylinder: The graduation values are 1 mL, 5 mL, and 10 mL

respectively.

5.1.2 Test procedures

Place the sample flat on a horizontal glass flat plate and fill it with water until the water

surface reaches the specified height. For pots, lidded cups, lidded bowls, and lidded

pots, the water surface shall reach the height at which the samples are filled with water

but the water shall not overflow after the samples are covered with lids. For uncovered

cups, uncovered bowls, uncovered pots, plates, and wine bottles, the samples are filled

with water to the overflow surface. For cooking devices, the samples are filled the water

to the edge of the lid. Use a measuring cylinder to measure the volume of injected water,

which is the sample volume. For samples with a standard volume less than 250 mL,

select a measuring cylinder with a graduation value of 1 mL; for samples with a

standard volume of 250 mL~1000 mL, select a measuring cylinder with a graduation

value of 5 mL; for samples with a standard volume greater than 1000 mL, select a

measuring cylinder with a graduation value of 10 mL.

5.1.3 Test data processing

The volume error is calculated according to formula (1), and the result is rounded to

one decimal place.

Ds -- standard diameter, the unit is millimeter (mm).

5.3 Determination of height error

5.3.1 Instruments and equipment

5.3.1.1 Steel ruler: The graduation values are 0.5 mm and 1.0 mm respectively.

5.3.1.2 Glass flat plate: The size shall be larger than the maximum size of the product

being tested. The flatness is checked with a steel ruler, and there shall be no obvious

gap between the glass flat plate and the steel ruler.

5.3.1.3 Vernier caliper: The graduation value is 0.1 mm.

5.3.2 Test procedures

Place the sample flat on a horizontal glass flat plate, and use a steel ruler or vernier

caliper to measure the distance from the bottom of the sample to the edge of the mouth

(excluding the cover) to obtain the maximum height and minimum height of the sample.

For samples with a standard height less than 30mm, select a vernier caliper; for samples

with a standard height of 30 mm~100 mm, select a steel ruler with a graduation value

of 0.5 mm; for samples with a standard height greater than 100 mm, select a steel ruler

with a graduation value of 1.0 mm.

5.3.3 Test data processing

The height error is calculated according to formula (3), and the result is rounded to one

decimal place.

where:

Rh -- height error, %;

Hmax -- maximum height, the unit is millimeter (mm);

Hmin -- minimum height, the unit is millimeter (mm);

Hs -- standard height, the unit is millimeter (mm).

5.4 Determination of weight error

5.4.1 Instruments and equipment

5.4.1.1 Drying oven: It can work at a temperature of 110 degrees C+/-5 degrees C. Microwave, infrared,

with a standard maximum size greater than or equal to 200 mm, select a steel ruler with

a graduation value of 1.0 mm.

5.5.3 Test data processing

The maximum dimensional error is calculated according to formula (5), and the result

is rounded to one decimal place.

where:

Rm -- maximum dimensional error, %;

M -- the maximum size of the sample, the unit is millimeter (mm);

Ms -- standard maximum size, the unit is millimeter (mm).

6 Determination method of defect size

6.1 Instruments and equipment

6.1.1 Steel ruler: The graduation value is 0.5 mm.

6.1.2 Vernier caliper: The graduation value is 0.1 mm.

6.1.3 Illuminance meter: The measuring range is not less than 1000 lx and the resolution

is 1 lx.

6.2 Test procedures

Use a steel ruler to measure various defects expressed in diameter, length or width, use

a steel ruler to measure and calculate various defects expressed in area, and use a vernier

caliper to measure various defects expressed in depth or height. For the identification

of defects without specified size and amplitude, under the light intensity of 300 lx~500

lx, place the defective front of the sample at a visual distance of about 500 mm for

visual identification. People who usually wear glasses can wear glasses.

6.3 Test data processing

6.3.1 For various defects expressed in diameter, such as ellipses or irregular shapes, the

diameter shall be calculated according to formula (6), and the result shall be rounded to

one decimal place.

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