BS ISO 12636:2018 pdf download – Graphic technology — Blankets for offset printing
The printing surface material formulation and surface texture are the choice of the manufacturer and may be stated in technical descriptions by the supplier. The surface texture may vary, e.g. cast (moulded) or ground (buffed). No specification for surface texture is given in this document. The measurement method is based on 5.8.
The use of data to market products is the choice of the manufacturer. The nominal (mean) thickness shall be stated in technical descriptions when ordered. Compressibility information should be given to the user and the test method shall be indicated. When testing the compatibility of blanket washes and an offset printing blanket, it is the option of the blanket manufacturer to report the test results using the test method according to 5.9 for each property. On the non-printing side of the cut-to-size blanket, the following should be reported: a) blanket dimensions (average actual thickness, width and length) indicating which dimension is the around-the-cylinder direction. If the recorded thickness is nominal, it shall be stated; b) the batch control number; c) the name of the manufacturer or the supplier and the blanket brand or trade name.
4.2.1 Thickness The test method according to 5.2 shall be used. For applications with packing, the nominal thickness should be 1,68 mm or 1,95 mm. For applications without packing, the nominal thickness should be agreed upon between the supplier and the user of the product. The thickness variations of blankets with an area not in excess of 1,5 m 2 shall be less than ±0,02 mm. Those of greater sizes shall be less than ±0,03 mm. No individual thickness measurement shall yield a value which deviates more than 0,05 mm from the ordered thickness.
4.2.2 Mean thickness Mean thickness is an average of four measurements of a cut blanket where the measurements have been made on the points indicated in Figure 1, namely on two diagonally opposed corners and one each at the middle of the two sides that are perpendicular to each other within a right triangle.
4.2.3 Accuracy of width and length
If one of the sides is 1 m or less, the tolerance shall be ±3 mm; otherwise, it shall be ±4 mm.
4.2.4 Plan view
The sides of the blanket shall form right angles. The difference between the length of the diagonals and the length of any two parallel sides shall not exceed 0,5 %.
The elongation, E, shall be less than 1,5 %. The test method according to 5.3 shall be used or any other method where results can be correlated to those of the test method defined in 5.3.
4.4 Tensile strength
For all blankets with a thickness of 1,68 mm or more, the tensile strength shall be greater than 40 N/mm.
The test method according to 5.4 shall be used or any other method where results can be correlated to those of the test method defined in 5.4. For blankets of lower thickness, no specification is given.
No specification is given. The test method according to either 5.6 or 5.7 shall be used. Alternatively, load at specific deflection (the test method according to 5.5) may be used.
4.6 Thickness change
4.6.1 Swelling and/or shrinkage due to printing ink component
The thickness change, ΔT, due to exposure to printing ink ingredients, shall not exceed 4 % maximum swelling or 2 % maximum shrinkage. The test method according to 5.9 shall be used for each property.
NOTE The blanket printing surface is typically designed for use with specific ink types. For example, UV blankets are designed for use with UV-cured inks.
4.6.2 Swelling and/or shrinkage due to blanket washes
Blanket washes should be tested for compatibility with the blanket according to the test method given in 5.9.
NOTE The choice of a proper wash is a difficult decision due to efficiency versus safety and environmental needs.
4.7 Cut blanket markings
The method and format for marking is the choice of the manufacturer.
5 Test methods
The testing environment should be (23 ± 2) °C. Relative humidity is (50 ± 5) % Rh.BS ISO 12636 pdf download.