SRI LANKA STANDARD 1222 : PART 2 : 2001
UDC 642.72:666.5
SPECIFICATION FOR
PORCELAIN TABLEWARE
PART 2 : TEST METHODS
SRI LANKA STANDARDS INSTITUTION
SLS 1222 : Part 2 : 2001
SRI LANKA STANDARD
SPECIFICATION FOR PORCELAIN TABLEWARE
PART 2 : TEST METHODS
SLS 1222 : Part 2 : 2001
Gr. 8
SRI LANKA STANDARDS INSTITUTION
17, Victoria Place
Elvitigala Mawatha,
Colombo 08.
SRI LANKA
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SLS 1222 : Part 2 : 2001
SRI LANKA STANDARDS INSTITUTION
SPECIFICATION FOR PORCELAIN TABLEWARE
PART 2 : TEST METHODS
FOREWORD
This standard was approved by the Sectoral Committee on Building and Construction
Materials and was authorized for adoption and publication as a Sri Lanka Standard by the
Council of the Sri Lanka Standards Institution on 2001 / 11 / 22.
This part of the standard specifies the test methods and Part 1 of this standard specifies the
requirements for Porcelain Tableware.
In reporting the result of a test or an analysis made in accordance with this standard, if the
final value, observed or calculated, is to be rounded off, it shall be done in accordance with
CS 102.
In the preparation of this standard the assistance derived from the publications of the
International Organization for Standardization, the British Standards Institution, and the
Bureau of Indian Standards is gratefully acknowledged.
1
SCOPE
This part of the standard prescribes test methods for porcelain tableware.
2 REFERENCES
CS 102
- Presentation of numerical values
ISO 3696 - Water for analytical laboratory use- Specification and test methods
ISO 835
- Laboratory glassware – Graduated pipettes – Part 1: General requirements
ISO 385
- Laboratory glassware – Burettes – Part 1: General requirements
ISO 1042 - Laboratory glassware – One mark – Volumetric flasks
3 TERMINOLOGY
For the purpose of this standard the definitions given in SLS 1222 : Part 1 : 2001 shall apply
in addition to the following definitions.
3.1 atomic absorption spectrometry (AAS):
Spectroanalytical method for qualitative
determination and quantitative evaluation of element concentrations wherein the technique
determines these concentrations by measuring the atomic absorption of free atoms.
3.2 atomic absorption: Absorption of electromagnetic radiation by free atoms in the gas
phase wherein a line spectrum is obtained which is specific for the absorbing atoms.
3.3 extraction solution: Acetic acid, 4% (v/v), recovered after the extraction test and which
is analysed for lead and cadmium concentration.
3.4 opaque: A nontransparent article.
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4
PHYSICAL TESTS
4.1
Determination of edge warpage and slope
Edge-warpage and slope of items of tableware shall be tested as follows.
Invert the sample and place it face down on a levelled surface. Place a weight across the
resting surface of the item to stabilize it in place. Attempt to insert a feeler gauge 2 mm
between the surface and any portion of the sample edge. Remove the weight from the resting
surface and replace it by an inclinometer and determine the slope of the resting surface.
4.2 Determination of whiteness
Whiteness shall be determined according to the following method using a Colour Tester.
4.2.1 Apparatus
4.2.1.1 Colour tester
An acceptable device for measuring colour to an accuracy of ± 1% having
a)
b)
a colour measuring head with photo optical section; and
an electronic display unit capable of recording Rx , Ry and Rz to be substituted in
equation in 3.2.3 to determine L, a and b values.
4.2.2 Procedure
4.2.2.1 Record the remission value RX by inserting X filter.
4.2.2.2 Record the remission value RY by inserting Y filter.
4.2.2.3 Record the remission value RZ by inserting Z filter.
4.2.2.4 Carry out the calculation as given in 3.2.3.
4.2.3 Calculations
X = A . RX + B . RZ
Y = RY
Z = C . RZ
where
RX
RY
RZ
is X filter reading of the whiteness meter
is Y filter reading of the whiteness meter
is Z filter reading of the whiteness meter
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Filter factors for standard illuminants
A = 0.7832
B = 0.1972
C = 1.181
The L, a, b, co-ordinates are directly related to the x, y, z co-ordinates
L = 10.0
Y
a = 17.5 (1.02 X-Y)
---------------------Y
b = 7.0 (Y-0.847 . Z)
---------------------Y
4.2.4 Test record
The test record should contain:
a) Reference standard - Specially prepared Barium sulphate or any other standard
calibrated with reference to Barium sulphate.
b) Filters with spectral ranges,
Where Red
=
Green =
Blue =
630 nm
560 nm
460 nm
c) Standard illuminate
4.3
Determination of translucency
4.3.1 Principle
The translucency of Porcelain Tableware is assessed as the ratio of the intensity of light
transmitted through a sample to the intensity of light incident upon it, expressed as a
percentage for a sample thickness of 2 mm.
4.3.2 Apparatus
4.3.2.1 Photometer, having a light source capable of emitting white light
temperature approximately 3400 K.
of colour
NOTE
The photometer should provide incident light in the form of a parallel beam normal to the
surface of the test piece and all transmitted light should be collected; the use of an instrument
incorporating an integrating sphere is commended as a means of achieving the latter.
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4.3.2.2. Uniform reference specimens, of accurately known translucency in the region
of 0.75%.
4.3.3 Sample preparation
Cut five discs, of a size corresponding to the size of the sample holder of the photometer to be
used, from the sample. Grind away the glaze on each side of each disc to provide test pieces
of approximate thicknesses 2.5, 2.25, 2.0, 1.75 and 1.5 mm with parallel unglazed faces.
4.3.4 Procedure
By means of the photometer determine and record the percentage transmission of white light,
of colour temperature approximately 3400 K , through each test piece and through the
uniform reference specimens.
Measure and record the thickness of each test piece to the nearest 0.01 mm.
4.3.5 Calculation and expression of results
Construct a graph of percentage transmission versus thickness for the five test pieces
examined. By interpolation, determine the translucency of the sample for a test piece
thickness of precisely 2.00 mm. Correct the value obtained by the photometer factor
determined by the results obtained from the uniform reference specimens.
4.4 Determination of thermal shock resistance (190 0 C)
A sample ware is heated in an oven to a temperature of 180 o C + room temperature in
a period of 2 hours and then quickly transfer it to room temperature and check for cracks.
4.5
o
C for
Determination of freezer safe
To determine if freezing of Tableware can cause any damage or visual changes.
4.5.1
Apparatus
4.5.1.1 Freezer
4.5.1.2 Coloured Dye Bath (Tank) of suitable size
4.5.1.3 Coloured Dye Ink (Methyl Violet)
4.5.2
Procedure
4.5.2.1 Prepare dye bath with visible ink dye.
4.5.2.2 Place testing sample in the tank for a minimum of 1 minute.
4.5.2.3 Remove, rinse and dry the sample and inspect for any damage revealed by liquid dye
penetration. If any damage is detected, select another test sample and repeat the process until
a sample free of damages is obtained.
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4.5.2.4 Place a number of wet sponges in the test sample filling to approximately
75% of the internal volume. Add additional water to ensure that the sponges are fully wet.
4.5.2.5 Place in freezer for a minimum 6 hours
– 15 o C to - 23 o C.
and to a maximum 24 hours duration at
4.5.2.6 Remove from freezer and leave to stabilize (Thaw out) to room temperature on
draining surface.
4.5.2.7 Place in the dye bath for one minute.
4.5.2.8 Remove from dye bath and dry sample.
4.5.2.9 Inspect for damage and any visible aesthetical changes.
4.6
Determination of water absorption
The amount of water absorbed by an article is determined as given below.
4.6.1 Test specimen preparation
Cut or break 5 test pieces from 5 different samples to get a surface area of about 16 cm2
each. The two flat faces of the test pieces shall be glazed and other sides unglazed and freshly
broken.
4.6.2
Procedure
Dry the test pieces to constant mass at a temperature between 110 o C and 115 0 C and then
cool to room temperature in a desiccator. Weigh the pieces accurately nearest to 0.01 g and
immerse in boiling distilled water for one hour taking care that they do not touch the sides of
the vessel. At the end of this period stop heating and leave the test pieces to cool to room
temperature in the same water. At the end of 24 hours remove the test pieces from water,
wipe with a damp cotton cloth to remove adhering surface water and weigh quickly.
4.6.3
Calculation
Calculate water absorption as follows :
Water absorption, per cent by mass =
M 2 − M1
x 100
M1
where
M2 = mass in g of the test piece after boiling in distilled water, and
M1 = mass in g of the dry test piece.
4.6.4
Test report
The test report shall include the following details:
-
An identification of the article tested; and
Report the average of results on 5 test pieces.
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4.7
Determination of impact strength and chipping resistance
This test is carried out to ensure that the tableware withstands impacts encountered in normal
day to day use without breaking or chipping.
4.7.1 Apparatus
4.7.1.1 Impact tester
A suitable pendulum type impact tester is illustrated in Figure 1.
4.7.2
Procedure
4.7.2.1 Impact strength
When testing a plate, saucer or platter, support the ware against three equally spaced 3 mm
diameter steel balls so that when the hammer is hanging vertically the impact point of hammer
touches the centre of the bottom of the test piece. When testing a cup or bowl, place the ware
on its foot between two cast iron blocks forming a 900 ‘V’ whose sides are sufficiently high to
support the upper edge of the cup or bowl and adjust it in such a manner that when the
hammer is hanging vertically its impact point touches the cup or bowl at its upper edge and on
the plane of the bisector of the angle of ‘V’. Strike the test piece with the spherical end of the
hammer with an impact.
A ware such as a plate, saucer or platter shall be considered as having failed in the test if it
develops a rupture which appears as a hole through the body or as a body crack extending
through its rim. A cup or bowl shall be treated as having failed if it develops a body crack
extending into any portion of the foot or a portion of the body breaks away.
4.7.2.2 Chipping resistance
This test shall be carried out on flat ware only. Place the plate or saucer on its foot between
two cast iron blocks forming a 900 ‘V’ and adjust it in such a manner that when the hammer
is hanging vertically the centre of the impact face of the chipping hammer touches the edge of
the test piece at the plane of the bisector of the angle of ‘V’. Strike the test piece at three
equally spaced points on its periphery with the cylindrical end of the hammer with an impact.
The ware shall be considered as having failed in the test if the impact results in chipping of
the edge so that fragments of glaze and body are removed.
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4.8 Determination of handle strength
Impact tests were made using free standing cups with the hammer directed at the side of the
handle with the Impact Testing Apparatus described in Figure 1.
4.9 Peel off test for decorated ware
4.9.1 Spalling test
Place test piece (270 mm plate is desirable) into dryer heated up between 100 0 C and 150 0 C
and keep it warm therein for 30 minutes.
Then, take it out of dryer and dip it into normal temperature water immediately.
Check if cracks have appeared on design surface, by a magnifying glass.
4.9.2 Outdoor leaving test
Leave the test piece outdoors for 6 days, under full exposure to outside atmosphere, but do not
expose it under rain.
This condition is equivalent to indoor condition for about 12 to 18 months.
Thereafter, paint methyl violet on design surface, strike it by test stick, and then wipe off the
methyl violet.
Check the cracks by magnifier. Cracked position may be identified easily by violet colour.
4.10 Determination of abrasive resistance
4.10.1
Abrasion testers
Abrasion testing for tableware can be carried out using the typical Pin Abrasion Tester shown
in Figure 2. This instrument subjects the sample piece to a pinhead coated in an abrasive
charge, which travels backward and forward. A knife holder is supplied along with an adapter
to hold curved surface objects.
Use of a gloss meter will give a repeatable evaluation of the abrasion caused by the pin head.
Gold / Platinum decorated lines should withstand 50 strokes with Pinewood pin head, without
causing any defects such as fading of surface luster, colour and peel off.
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SLS 1222 : Part 2 : 2001
5.0
CHEMICAL TESTS
5.1
Determination of lead / cadmium dissolved content
5.1.1 Reagents
5.1.1.1 Generally, all reagents shall be of recognized analytical quality.
5.1.1.2 Water, complying with the requirements of ISO 3696.
5.1.1.3 Acetic acid (CH3 COOH), glacial
5.1.1.4 Acetic acid solution (4% V/V). To 500 ml of water (4.1.1.2) add 40 ml of glacial
acetic acid (4.1.1.3) and make up to 1 litre. Freshly prepare the solution prior to use in
sufficient quantity to enable the whole of any group of tests and analyses to be completed.
5.1.1.5 Standard metal solutions.
5.1.1.5.1
1000 ± 1 mg Pb in l Liter of 4 % V/V acetic acid (4.1.1.4)
5.1.1.5.2
500 ± 0.5 mg Cd in 1Liter of 4 % V/V acetic acid (4.1.1.4)
NOTE
Commercially available standard solutions for atomic absorption spectroscopy may be used
provided that the concentrations of such solutions are known to an equivalent accuracy.
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SLS 1222 : Part 2 : 2001
5.1.2
Apparatus
5.1.2.1 Atomic absorption spectrophotomer, with a detection limit equal to or better than
0.2 mg/l Pb (in 4% V/V acetic acid) and 0.02 mg/l Cd (in 4% V/V acetic acid).
NOTE
The detection limit is the concentration of the element which gives a signal equal to four times
the standard deviation of the background noise level of the instrument.
5.1.2.2 Laboratory glassware
Volumetric glassware of class B, or better, accuracy as specified in ISO 835 , ISO 385 or
ISO 1042, as appropriate. General laboratory glassware of borosilicate glass incapable of
releasing detectable levels of lead or cadmium into 4% acetic acid during the test procedure.
5.1.3 Preparation of samples
Wash the sample in an aqueous solution at 40 ± 5 o C containing 1 ml/l of domestic liquid
detergent. Rinse the sample thoroughly with water (4.1.1.2) and allow to drain, then wipe dry
with clean filter paper. Do not use any sample which shows residual staining.
If the sample possesses an area of its surface which is not intended to come into contact with
foodstuffs in normal use, other than the interior of any lid, cover this area after the initial
washing and drying with a protective coating which will withstand the effect of 4 % V/V
acetic acid and which will not release any detectable levels of Pb or Cd into 4 % V/V acetic
acid during the test procedure.
NOTE
High melting point paraffin wash is a suitable coating. Do not handle the surface to be tested
after it has been prepared.
5.1.4 Procedure
5.1.4.1 Condition the sample to 22 ± 2 o C. and, determine and record the surface area of the
article.
5.1.4.2 Fill the conditioned sample with 4 % V/V acetic acid solution , (4.1.1.4)) at 22 ± 2o C
to a level no more than 1 mm from the overflow point, measured from the upper rim of the
sample, and to no more than 6 mm from the extreme edge of a sample with a flat or sloping
rim. Samples which cannot be filled should be completely immersed in the minimum amount
of 4% V/V acetic acid.
Record the quantity of 4% V/V acetic acid required to an accuracy of ± 2 %. Record the
quantities separately where an item with a lid is tested.
5.1.4.3 Where tests are conducted for both cadmium and lead, cover the sample and ensure
than throughout the test procedure the surface under test is kept in complete darkness.
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NOTES
1. If only lead is to be determined the test may be conducted in normal lighting.
Maintain the filled, or immersed, sample at 22 ± 2 o C for 24 ± 0.5 h under conditions
which preclude evaporative losses.
2. Plastic trays with close fitting lids are suitable containers to prevent evaporative losses
form the test vessels.
5.1.4.3 Homogenize the extract solution, by stirring or other method, without loss of solution
or abrasion of the surface being tested and withdraw a portion for the determination of
lead and / or cadmium.
NOTE
A method of homogenizing the extraction solution is to remove a quantity by pipette and
allow it to runback into, or onto, the sample several times, avoiding dilution or evaporation
loss in the process.
5.1.5
Analysis
5.1.5.1 Set up the atomic absorption spectrophotometer having regard to the manufacturer’s
instructions using wavelengths of 217.0 nm for lead determination and 228.8 nm for cadmium
determination with appropriate correction for background absorption effect.
NOTE
Where appropriate, a wavelength of 283 nm may be used for the analytical confirmation of
lead.
5.1.5.2 Aspirate water (4.1.1.2) and adjust the zero. Aspirate a range of dilute standard metal
solutions prepared by dilution of the standard metal solutions (4.1.1.5) with 4% V/V acetic
acid solution. Aspirate water (4.1.1.2) after each standard metal solution (4.1.1.5) and record
the absorbance values obtained.
5.1.5.3 Aspirate water (4.1.1.2) and then 4% V/V acetic acid (4.1.1.4) and measure the
absorbance value.
aspirate the sample extracts (see 4.1.4.4), accurate diluted where
appropriate, interspersed with water (4.1.1.2). Measure the absorbance values of the sample
extracts or accurately diluted sample extracts.
5.1.6
Test report
The test report shall contain:
5.1.6.1 The nature of the article under test;
5.1.6.2 The surface area or volume, as appropriate, of the article;
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5.1.6.3 The amount of Pb and or Cd in the total quantity (ies) of extracting solution (s)
expressed as milligrams of Pb or Cd per liter of volume.
5.2
Determination of dish washer proof
To assess the effect of dishwasher detergents on Porcelain ware
5.2.1 Reagent
The alkaline dishwasher detergent , at a concentration of 0.4 % by weight in distilled water.
Sufficient detergent solution shall be prepared to ensure that the total ware surface area to
volume of detergent solution is not less than 70 cm2 /litre and does not exceed 130 cm2 /litre.
5.2.2 Test specimen
A test specimen is any item of decorated Porcelain ware which can be completely immersed
in the detergent solution.
A minimum of two specimens of similar ware is required.
5.2.3 Procedure
5.2.3.1 Hand wash the test samples in warm water containing a little, non – aggressive
hand dishwashing detergent. Rinse and dry with a clean cloth.
5.2.3.2 Examine the sample by eye (with the aid of spectacles if normally worn) in the
viewing cabinet. Retain one specimen for comparison after testing.
5.2.3.3 Determine the surface area of the specimen and satisfy the surface area to volume
criteria, (see REAGENT Section). Cover the tanks and adjust the water bath temperature to
77 ± 1 0 C. Add sufficient dishwasher detergent to give a 0.4% solution and stir well to
disperse. Immediately lower the test specimens in the racks in to the tanks and cover .
Maintain the detergent solution at 77 ± 1 0 C.
5.2.3.4 After 16 hours ± 10 minutes, remove the specimens from the detergent solution , rinse
with hot water and rub dry with a clean cloth. The rubbing action may also remove any loose
decoration. Repeat the immersion procedure for a further 16 hours, using a fresh detergent
solution, remove the test specimens and rinse and dry as above.
5.2.3.5 Examine the ware as described in heading 2 of Table 1, comparing the tested
specimen(s) with the untested specimen for changes in gloss or colour.
5.2.3.6 Report any changes in gloss, colour of the decoration using the Table 1 for guidance.
5.2.3.6.1
Little or no noticeable effect on the gloss or shade.
5.2.3.6.2 Slight attack on some of the colours, mainly reduction in the gloss but some fading
may also be present.
5.2.3.6.3
Reduction in gloss or fading of most colours.
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5.2.3.6.4 Considerable attack on most colours and complete removal of small areas of
colour of up to 1 mm in diameter.
5.2.3.6.5 Severe attack, involving substantial removal of colour.
NOTE
When determining the surface area of flatware, it is sufficient to determine the surface area
of a flat disc having the same circumference as the ware. For other types of ware , allowance
must be made for the curvature of the ware and for handles etc.
5.3
Alkali poof test
Dip test pieces in to the 0.5 per cent solution of sodium carbonate in the controlled water
bath at 100 0 C for 2 hrs.
Wash them thoroughly with water and rub them with a dry cloth.
5.4
Neutral cleanser proof test
Dip the test piece into the 0.5 per cent solution of neutral cleanser. Leave this vessel in the
controlled water bath at 60 0 C for 96 hrs. Wash it thoroughly with water, and rub it with dry
cloth.
5.5
Acid proof test
The test piece is dipped in to 4 per cent solution of acetic acid and is left at 25 0 C to 35 0 C
for 24 hrs. It is washed thoroughly with water and is rubbed with a dry cloth.
5.5.1 Other proof standards
Test pieces are subjected to the following standards after completing the above tests:
TABLE 1 – Standard grades
Grade
Item
0
1
2
3
4
Surface
lustre
Colour
fading
Unchanged
Slight matting
No lustre
-
Unchanged
Slight fading
Considerable
matting
Considerable
fading
Extremely
fading
-
Colour
change
Unchanged
Slight
discoloration
Considerable
discoloration
Extremely
discoloration
-
Peel off
Unchanged
Unchanged
Unchanged
Starting to peel
off
Peeled off
If one of the above item was found to be in Grade 2, 3, or 4 the test piece is considered as
rejected.
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SLS 1222 : Part 2 : 2001
5.6 Boiling water proof test
Leave the test piece in 80 - 100 0 C controlled water bath for 24 hrs. Wash it thoroughly with
water and rub it with dry cloth. Examine the fired pigment / gold / platinum for any defects.
6 SAMPLING
Sampling shall be conducted according to the Appendix A of SLS 1222 : Part 1 : 2001
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