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Tar‐impregnated paper strips, 2m long and 20cm width were painted with 1–1.25mm thick yellow traffic paint. Sand gravel having a grain size 2.0 + 1.5 mm was uniformly screened over the wet paint film. The dry painted samples were fixed on pavements of Jeddah‐Taif highway during the summer [42 ± 2°C]. The mechanical wear rate was determined and compared with that of sand‐free paint.

The specific influence of calcium and sodium cations on the rate of deposition of a‐Fe2O3 (a main corrosion product in boilers and heat exchangers) has been experimentally studied. A deposition model based on the microlayer evaporation and dryout phenomena that occur in the nucleate boiling bubble is put forward for interpretation of the deposited layer. It has been found that the rate of deposition of Fe2O3 increases with the increase in valency of the soluble cations. With calcium, the deposition rate increases linearly with the increase in its ionic concentration, whereby the rate is increased by 5.9, 6.8 and 7.6 with 200, 400 and 600 ppm calcium respectively. Development of the deposition layer takes place in the valleys of the surface contour according to a micro‐layer evaporation mechanism. Successive deposition is performed at the periphery of the first deposit. Reduction in cation content in the crude solution and selecting smooth heated surfaces are recommended to reduce the ∝‐Fe2O3 deposition on heated surfaces in boiling water.

Ball‐point ink is a heterogeneous, viscous multi‐phase fluid. It consists of resins, solvents, diluents together with solid pigment and filler. The fluid is contained in a thin polyethylene tube which acts as a fluid reservoir continuously supplying the ink to a narrower brass tube. The latter has an inner diameter of about 0.8 mm and holds a small ball at its tip. During storage for long periods, agglutination of the ink takes place in the brass tube and around the ball as well. The rate of such agglutination is strongly related to the environmental conditions. In the present work, a technique is developed to measure the thickness of the agglutinated ink film by means of a microscopic examination. Hence the thickness of the deposited solid layer on the internal periphery of the brass tube will be estimated. Furthermore, factors affecting the agglutination process will be investigated and methods to decrease or even to eliminate that phenomenon will be put forward.

The European association of pigment and dye manufacturers established a method for the estimation of heat and light fastness of organic pigments. In such method, pigments were dispersed in partially dried linseed oil whereby prints were made on standard writing paper. Degraded prints were visually estimated after comparing with a freshly prepared standard scale of 8 grades. A sample similar to scale 5 or more was considered to be of good or excellent fastness. Practically, it became familiar with controversial personnel estimations, especially in regard to the critical level of 4–5. Furthermore, the specific side effect interference of the linseed oil resin could not be avoided. It becomes reasonable to put forward a method depending on instrumental measurements. In the light of this method, heat and light fastness of organic pigments can be colourimetrically determined. The pigment is pasted in water containing 2–3% weight of sodium silicate as binding agent. Thin film prints are then made on a transparent non‐porous standard paper 80 g/m2. Prints are dried over P2O5 in a desicator placed in a cool and dark place. The dried prints are striped in 2cm width. Some of these stripes are taken for the colourimetric determination of the colour density with the help of a colour densitometer. Other stripes are subjected for 72 hours to daylight (not to direct sun rays) or placed in a drying oven maintained at the required temperature for the same duration. For colour density measurements, prints are underlined with 100 g/m2 white standard paper. Peak heights obtained with certain light wave‐length are computed with reference to the peak of the undergraded sample. It has been shown that a change in heat or light fastness as low as 2% can be determined with an accuracy range of 0.5% compared to 12.5% and 3.5% for the European method respectively.

Previous articles in this series have considered techniques of paint analysis, as well as methods of studying surfaces and interfaces and ways of following the various physico‐chemical reactions which occur within coatings, particularly those concerned with film curing. Many of the techniques described in these articles required sophisticated analytical equipment and certainly in larger organisations the care and operation of this would be in the hands of specially trained personnel. There are however, a wide range of tests which paint chemists more or less routinely use in their day to day work on formulation control and development. These are the types of test which charactertise liquid or paint film properties such as viscosity (which has been considered in a previous article), colour and gloss, drying time, hardness, durability etc. The equipment used in these tests tends to be less complicated than required for many of the techniques described in the previous articles though as much care and attention to detail is required in operation and interpreting the data obtained. The last two parts in this series will be concerned with a review of some of the recent literature concerned with certain aspects of paint film testing. This article will consider test panel preparation and some of the literature concerned with measuring gloss level and film mechanical properties. Recent advances in the field of durability and corrosion testing will form the basis of a subsequent article.

Tankfreight Ltd., of Harrogate, part of the employee‐owned National Freight Consortium, has been awarded a major contract by Vinyl Products on the basis of their ability to offer an extremely economical all‐round package.

Peter Moore has joined Neumo of Newhaven as product manager. He will be responsible for the Feige filling machinery range, for which Neumo has been appointed exclusive UK agent.