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Notes of Guidance

Appendix 1

Guidelines for the advertising of disposable nappies (diapers)

Advertisements can claim superiority with respect to one or more of their features, and this should also be possible for disposable nappies. For instance, detergents can claim to be superior with respect to cleanliness, stain-removal, dye-fading, softness, and reducing fabric damage. There is a range of features where superiority can be claimed for disposable nappies, and parents are most likely to be concerned about the following:

  1. 1. wetness/dryness of the baby’s skin;
  2. 2. leakage/capacity of the nappy;
  3. 3. comfort/red marks due to pressure;
  4. 4. prevention/relief of nappy rash;

Other factors may also be important, such as convenience of use, disposal, fragrance, colour, texture, and so on, but we feel these are not likely to be used in superiority claims (although they may well influence the customer into choosing a particular product).

The four categories identified above are the ones on which comparative claims are likely to be based. The features are not entirely independent of one another, although they do arise from different parts of the product, and the Panel feel that claims of superiority in one or more of them would be acceptable to Clearcast.


Although it clearly has its limitations, the Panel are persuaded that the evaporimetry test, known as the trans-epidermal water loss test (hereafter TEWL), is currently the best scientific method for measuring the wetness of skin. This records the release of water vapour from the uppermost layer of the skin, the stratum corneum. The method fits the criteria for scientific validity: it gives reproducible results, these results can be achieved in any laboratory with trained personnel, and the results are meaningful. Until an alternative, and more reliable, method of assessing skin dryness is developed, the Panel feels that superiority claims should derive from TEWL measurements.

It is the Panel’s recommendation that a superiority claim with respect to skin dryness should only be accepted if it can be demonstrated in tests carried out on both female forearms and on babies bottoms, and the Panel believes that the latter form of testing is best done after overnight wear, although for nappies designed for the youngest babies this should be for at least 4 hours.

Adult female forearms

TEWL studies on adult female forearms appear to be an excellent methodology, giving stability and reproducibility of measurement, and control of perturbing variables. Tests on adult female forearms offer the best site for wetness testing on soft skin that most resembles a baby’s skin. This form of testing is known to give reproducible measurements, although clearly it cannot take into account zonal variability in the characteristics and behaviour of human skin. Despite this limitation, the Panel feels that female forearm TEW L testing is an acceptable way of comparing skin dryness beneath a wet nappy, and Appendix 1 of this report gives the protocol which should be followed when carrying out such tests.


The Panel feels that, before a superiority claim for dryness can be accepted, there has to be supporting evidence based on real-life consumer use, and testing a baby’s skin after it has worn a nappy overnight would best seem to meet this requirement.

Again the body-regional variability of human skin characteristics and behaviour is such that testing must involve statistically meaningful numbers and sub-groups of babies, and that there must be standardization in the positioning of the baby for testing, the region where the probe is applied, and the way in which the probe is used.

On-baby testing is not without its problems because it is not physically possible to measure skin wetness in the immediate genital area of a baby, nor is it likely that mothers would approve of, or cooperate in, tests in this area. In any case this is not the area of skin which is likely to be pressed against the surface of the nappy during wear. Absorbent nappies are designed to disperse urine away from the point of insult, and skin adjacent to the pubic region will consequently be beneath wetted material. The part of a baby most likely to be pressed against a wetted nappy is its bottom, and the Panel feels that it is practicable to carry out a TEWL test in this region as near to the gluteal grove as possible. Appendix 2 lists the requirements that must be met for such testing to give acceptable results.

Prior to the launch of a new, or improved, product designed to reduce skin wetness, the samples of nappies to be tested must be of representative quality to those that are to be marketed. Likewise the purchase of competitors’ nappies should be made in such a manner as to ensure they are also representative. When a superiority claim is being made for a product that is already widely available then all samples for testing, including those of the would-be claimant, should be purchased simultaneously from the same outlets.

The alternative method of demonstrating the potential of a nappy to keep a baby’s skin dry is a re-wet test, in which another surface is pressed against a wetted nappy and the amount of fluid removed is measured. While such tests are much easier to carry out, and are likely to give reproducible results to a higher level of scientific acceptability, the Panel were persuaded that they were of secondary importance in assessing what actually happens during use.

However, re-wet demonstrations have been used in advertisements, and may continue to be so used. To be acceptable, the demonstration must simulate the conditions to be expected during nappy use, such as a reasonable time for the nappy’s absorbency to work; the application of a pressure similar to that experienced when the nappy is being worn by a baby; and the use of a re-wet surface that resembles skin. In using such a demonstration no impression of dryness superiority may be stated or implied unless superiority has also been demonstrated by both the female forearm and baby’s bottom TEWL tests.

Recommendation: that advertisers should be allowed to claim superiority in keeping a baby’s skin dry. Dryness ability must be proved using the two TEWL tests specified, but may be demonstrated to viewers in other ways.


It should be permitted to claim that a nappy is capable of holding more urine and semi-liquid faeces without there being any leakage. During the course of a night a baby may urinate into a nappy several times and there is a possibility that the garment may approach its holding capacity.

The capacity of a nappy to retain body waste does not necessarily correlate directly with the amount of absorbent material used in the nappy. The Panel accepts that improved retention capacity for a nappy would be a reasonable claim to make, but this must not be rely solely on there being more of the absorbent polymer present. This has to be shown to work effectively, and that a larger nappy loading is being retained, without leakage, under conditions that simulate its being worn by a baby.

Recommendation: that advertisers should be allowed to claim that their product can cope with more body waste without leakage. This would only be permissible if it can be demonstrated that competitive products would leak when subject to normal waste levels.

3.Comfort/red marks

There are several ways a nappy that could cause a baby discomfort. These stem from features such as insufficient choice of nappy sizes for appropriate age groups, poor adjustability in fastenings, the need for tightness of elastic grips to prevent leakage, and the quality of the material in contact with baby’s skin. Although these features are not easily measured, the Panel believes that a product which seeks to eliminate them could claim superiority in comfort of wear, where discomfort is evidenced by red weals on the body, and chaffing and chapping of the baby’s skin.

Advertisers should bear in mind that were such superiority claims regarding comfort of wear to be made, then the Panel would need to consider and approve protocols in advance of testing.

Recommendation: that advertisers should be allowed to claim superiority in comfort and wearability over extended periods of time.

4.Prevention/relief of nappy rash

Ways of preventing, helping to prevent, or relieving this skin condition could result from uniqueness of nappy construction, improved ventilation, or special ingredients designed for the purpose. Construction could include better locking away of urine and keeping it separate from faeces, while better air-flow by means of vents or ‘breathable’ materials could be used to reduce humidity. Nappy rash might also be checked by the use of anti-microbial and anti-enzymatic agents in a section of the nappy, or by having skin-protection agents or emollients as part of the surface that is in contact with the baby.

Again advertisers should bear in mind that if such claims are made, Clearcast suggests it would submitting protocols before testing.

Recommendation: that advertisers be allowed to claim hygiene benefits that help prevent nappy rash.