ISO 3998:1977 pdf download – Textiles – Determination of resistance to certain insect pests
Some methods previously utilized for testing resistance of textiles to insect pests relied solely on loss of mass of the test specimens exposed to larvae as the criterion of darnage and this is, of course, the most objective result which tan be obtained. However, with pile fabrics, if the larvae tut the roots of the pile or nap, significant loss of pile tan sometimes be caused before the larvae die. In this case, the loss in mass of the test specimen may be above the generally acceptable limit although no darnage is visible to the naked eye, and the fabric may be accepted as adequately proofed. Conversely, fabrics with a smooth milled surface, and fine knitwear, may have a loss in mass below the acceptable limit, but still show enough darnage for them to be assessed as insufficiently proofed. Thus although determinations of mass are recorded in this method, subjective visual obser- vations on the condition of the fabric and larvae play an equal part in the assessment. In most cases the losses in mass will reinforte the visual observations.
1 SCOPE AND FIELD OF APPLICATION
This International Standard specifies a method for the determination of the resistance of textiles to the larvae of certain insects. It is applicable to all textiles containing animal fibre in any proportion. Information relating to the breeding of the larvae is given in the annex.
2 PRINCIPLE
Conditioned voracity control specimens and test specimens of known mass are placed in contact with selected larvae for 14 days. The loss in mass of all specimens, the extent of the attack on test specimens and the condition of the test larvae are ascertained to assess the resistance of each test specimen.
3 APPARATUS
3.1 Metal containers, the covers of which are pierced with ventilating holes, shallow, large enough to permit the test larvae to remain in contact with, or move away from, the test specimens. A suitable size is 45 mm diameter, 10 mm height.
5.1.1 Test specimens
Select at random eight test specimens from the sample of material to be tested, at widely spaced intervals. Use four of these as test specimens and four as moisture regain controls.
5.1.2 Test control specimens
As it is essential to provide a control on the larval voracity, select eight test control specimens of undyed unproofed wollen material or yarn corresponding to the sample to be tested. Use four of these eight specimens as voracity controls and four as moisture regain controls. NOTE – A test control specimen should he known to support insect growth and should preferably, but not necessarily, be of the same type of material as the test specimen. A test control specimen is used to check that the test has been done correctly and that the test larvae are viable.