Testing of Paper and Board

The proper selection of relevant analysis and test methods for raw materials, intermediate or final products obviously has importance for the success of a testing program. Process and product analysis are the main areas for a large variety of very heterogeneous testing methods. Process analysis tries to define the control variables of the process that allow it to mn smoothly and produce products with the necessary properties. The aim of product analysis is to define the properties that relate to the use of a specific product or material. The test results obtained should be representative for all of the paper from which the sample has been taken. Reliable, representative measuring results require 

A straightforward process for cut-size and reel paper is described in ISO 186 

As a result of its hygroscopic properties, paper and board must be tested under standard climatic conditions and the samples must be conditioned in this climate for at least 4 hours before testing (sample conditioning). In ISO 187 (1990), the preferred climate for paper testing is specified as 23 °C and 50% relative humidity. In the following the most relevant test methods for paper and board testing -will be described. 

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In the following sections some requirements for toxicological screening tests applicable for paper and board are outlined, the presently available tests are briefly reviewed, and some examples of the actual applications of toxicological test to paper and board are given (section 15.5). 

The application of short-term tests to paper and board... 

So far there have been relatively few published reports on the application of in-vitro toxicological tests to extracts of paper and board. The published results relate to the use of photobacterium test, RNA-synthesis inhibition assay or to a battery of different test systems. The outcomes of these trials are summarised below. 

It is fundamental to a good understanding of paper and board that the testing regimes that can be used and the specific tests and the reasons for using those tests are appreciated. 

Sample conditioning of paper and board BS EN 20187 1993, ISO/R187 1990. This is the way to condition any test piece prior to testing by the appropriate BS method. 

Moisture content of paper and board is measured according to BS 343 1986 (91) ISO 287 (1985). All papers and boards can be covered, i.e. all calipers of paper, chipboard, pasteboard, folding boxboard, solid and corrugated fibreboards provided there are no substances that will escape at the temperature specified for the test. 

Folding endurance ISO 5626 1993 describes four methods, i.e. Kohler Molin, Lhomary, MIT and Schopper. These various instruments fold the test piece back and forth through a specified angle until rupture occurs. Applies to all forms of paper and board, but there may be different instruments for different boards. 

There is a wide variety of different in-vitro tests that could be applied to extracts of food contact paper and board. However, there are few published reports of their use for this purpose, and at present it is not possible to form a consistent picture of their general applicability. The outcomes of the three most comprehensive studies published so far (Fauris et al, 1998 Binderup et al, 2002 Ozaki et al, 2004) illustrate this point. While all studies agree that the toxicity is correlated with the chemical complexity of the paper and... 

SEVERIN I, DAHBI L, LHUGUENOT J-C, ANDERSSON MA, HOORNSTRA D, SALKINOJA-SALONEN M, TURCO L, ZUCCO F, STAMMATI A, DAHLMAN O, CASTLE L, SAVOLAINEN M, WEBER A, HONKALAMPI-HAMALAiNEN u and VON WRIGHT A. (2005) Safety assessment of food-contact paper and board using a battery of short-term toxicity tests European Union BIOSAFEPAPER project. Food Additives and Contaminants 22 1032-1041. 

Substances linked with producing odour and taint include short chain aldehydes. In paper and board, these are considered to derive from the degradation of lipids. Pentanal, hexanal, heptanal and nonanal were shown to be volatilised from paper and board materials heated at 60 to 100 °C (Wenzl and Lankmayr, 2002). Other substances were also detected in the headspace above the test samples but were not identified. Whilst transfer to foods was not investigated in these studies, the fact that they were shown... 

Triantafyllou et al. (2005), in studies on transfer of potential contaminants from paper and board to food, measured partition coefficients between packaging and air for a range of substances. This was, therefore, an attempt to measure the potential for gas-phase transfer. A mixture of acetophenone (b.p. 203 °C), naphthalene (b.p. 218 °C), benzophenone (b.p. 306 °C), dibutyl phthalate (b.p. 340 °C) and methyl stearate (b.p. 443 °C) was placed in a vial together with samples of test liner made from virgin fibres or triplex board made from 100% recycled fibre. There was no contact between the substances and the paper or board. Vials were sealed and heated at 70 °C or 100 °C and then the paper removed and analysed for uptake of substances. Conclusions from the studies were that ... 

Within an investigation to develop rapid test methods to determine the migration from paper and board into food ° the migration of dibutyl phthalate, diisobutyl phthalate and DIPN from a corrugated board intended for use for... 

Pre-test procedures for paper and board. BS 3430 1986 (91) ISO 186 (1985) sets out the methods of obtaining a representative sample of the paper or board for testing in order to ensure that an average can be taken and compared with the original specification. 

Dennison wax test. This is an older test that was largely replaced by the IGT test, but is still used by some older paper and board mills. It consists of a series of specialised waxes, which are heated to a specified temperature, placed on the paper surface, left to cool, then removed. The wax formula picks dust and debris from the surface, and the wax formula number that shows the picking indicates the degree of ink viscosity (or stickiness) that the particular paper will tolerate without risk to the print. 

ASTM D1922, usually known as the Elmendorf tear strength (related to test originally devised for paper and board), is carried out in the machine (MD) and cross (CD) direction of the material. Measured as kN/m. Test D689-44 also applies for films. 

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