122 PAINT TECHNOLOGY AND TESTS 



years, during which period the chalking of paints has been shown 

 to be greatest and the chalked surface of a fairly adherent nature. 

 Where longer exposures have been made and where rains have 

 removed from the painted panels a considerable amount of the 

 chalked pigment which has formed, such a test would not be 

 fairly representative of the amount of chalking which had taken 

 place. 



Gloss. The gloss of the various panels was a condition which 

 was also reported upon, the middle board of each panel being 

 washed with a wet sponge one day before the inspection so that 

 any surface dirt might be removed. By looking at a panel 

 from the side, a day after the washing, the inspector was enabled 

 to get a fair idea of the degree of gloss exhibited by each formula. 



Hiding Power. The hiding power of each paint was deter- 

 mined, as before described, by observing the degree to which 

 the stencilled lampblack cross on the priming coat was visible 

 through the second and third coats. Single pigment paints 

 such as white lead possessed very great hiding power and ob- 

 scured the black cross almost completely, while the cross was 

 quite visible through paints containing high percentages of 

 crystalline pigments. 



Checking. The checking of each panel was .determined by 

 examining with a small high-power hand glass magnifying fifteen 

 diameters. It is well known that examinations with such a 

 hand glass will not determine whether so-called fine matt check- 

 ing is taking place, but it will determine whether checking has 

 appeared to any marked extent. Fine matt checking is the 

 first sign of the decomposition of a paint, and is preliminary to 

 the visible checking seen by the naked eye, which is often followed 

 by alligatoring. Examination of some formulas disclosed this 

 so-called alligatoring and even the exposed wood between the 

 fissured surface which had developed from what were at first 

 fine hair checks. It is, in the opinion of the writer, possible to 

 predict with a fair degree of accuracy by examination of a painted 

 surface, one year after exposure, how the paint will wear in the 

 future and what its appearance will be at the end of another 

 year. 



Hardness. The hardness of each panel could not be deter- 

 mined with any degree of accuracy, but the inspectors were able 

 to roughly determine this condition by very close inspection. 



