. Electric railway journal . by foremen who trust the priming coatto helpers. The essential requisites of the prime coatare firm adhesion, impermeability and a uniformity ofthe layer of the thickness desired. These can only beobtained by a first-class mechanic who thoroughly un-derstands the importance of brushing out his paint. Nothing is more discouraging to the foreman painterthan to find, after a job has been finished, that thesurface is covered with minute and large blisters. Thiscondition is far more common on cars finished with anoil enamel, which is used extensively in car paintingtoda
. Electric railway journal . by foremen who trust the priming coatto helpers. The essential requisites of the prime coatare firm adhesion, impermeability and a uniformity ofthe layer of the thickness desired. These can only beobtained by a first-class mechanic who thoroughly un-derstands the importance of brushing out his paint. Nothing is more discouraging to the foreman painterthan to find, after a job has been finished, that thesurface is covered with minute and large blisters. Thiscondition is far more common on cars finished with anoil enamel, which is used extensively in car paintingtoday, than on cars painted by the older process. Whileit is true that in some cases blistering is due to an ex-cess of oil or fat in the oil, in the majority of casesblistering can be justly attributed to painting overdamp or moist surfaces. Blisters are more than mereblemishes on the paint film, they are serious defectswhich if allowed to persist will ultimately destroy theentire painted surface. In due time the blisters will. A SMOOTH DRY SURFACE IS ESSENTIAL IF BLISTERFORMATION IS TO BE PREVENTED crack and allow water to get in under the paint filmitself and thus destroy the under coats. Where the job calls for the car to be scrubbed andenamelled, care should be taken to see that the surface isthoroughly dry before the enamel is applied. If thesurface is damp or moist vv^hen the enamel is appliedcountless water molecules will spread over the surfaceunder the thin enamel film; When the car leaves theshop the rays of the sun beating upon the surface ofthe car will draw these molecules of water together ata point where the structure of the paint film shows theleast resistance. While the paint is drying it is constantly taking onoxygen. The moisture, oxygen and oil, aided by theheat of the sun, tend to generate a gas under the causes the expansion which we call blisters. Ofcourse these factors do not absolve the paint manufac-turer from all blame and it is all up to the f
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