Iron corrosion : anti-fouling and anti-corrosive paints

Front matter

FRANKLIN INSTITUTE LIBRARY

PURCHASED WITH INCOME OF THE

Book. An Z3

Preface

Since the great extension that has taken place in the emi)loyment of iron for all structural jmrposes, and in particular as the exclusive material for bridges over which enormous loads have to be transported in a very short space of time, increased attention has been bestowed on the preservation of these structures, and the more so because of the great tendency to oxidise exhibited by this metal under the influence of air, moisture and fluctuations of temperature. The iron oxide, ''rust," formed by combination with oxygen assisted by the conjoint action of carbon dioxide and water, is a very dangerous as well as an unwelcome enemy to all iron structures ; since, where it has once gained a footing, it is difficult if not impossible of eradication, and its formation in places inaccessible to periodical examination may, by the corrosion of screws and rivets, readily endanger the safety and strength of the structure. Owing to tlu^ desirability of suitably preserving ironwork from corrosion, by reducing the formation of rust to a minimum, and thereby obviating the danger aforesaid, there has appeared — ^practice having determined that the best iv

PREFACE.

protection is afforded by oil paint — a large number of soi-disant positively infallible anti-corrosive paints claiming to ensure illimitable durability, though the experience gained by their use in many critical instances has been the reverse of favourable. The same fate has attended the use of ordinary oil paints, because, despite the teachings of experience, it has been the custom to look upon painting — especially laying on the first coat — as a merely formal matter, and to attempt to economise," both in material and w^orkmanship, by buying the cheapest paint and entrusting the work to day labourers.

The International Congress for the unification of methods of testing building and other structural materials has been the means of again raising the question of iron corrosion, and afforded the author, who had long been collecting data on the subject, an opportunity of occupying himself thoroughly with the question.

The illustrations of the rusting of iron given in the following pages were prepared in the course of a series of personal experiments on the formation of rust, the results of which are now embodied with the experience gained in reference to anti-corrosive paints, so that I may hope to have presented in the present work a fresh contribution towards the solution of this important problem.

LOUIS EDGAR ANDES.