A number of pyrotechnic manufacturers have expressed their opinions, based on their experience over a number of years, as follows:
As regards the length of time pyrotechnic pieces may be safely stored, one manufacturer states that he has held pieces in storage as long as twenty years and found them to still function properly. However, he quotes the European rule of destroying material after a period of three years. He also states that signal rockets as used on shipboard are usually destroyed after a period of three years' storage, except where the ships ply in southern climates, when such units are destroyed after the second year.
Another manufacturer states that he has stored pyrotechnic articles for ten years without serious depreciation. Another manufacturer states that during a period of thirty years he has stored fireworks at various times, frequently during long periods, and has never had a fire or found that any serious changes had taken place in the material.
As regards the relative functioning efficiency after certain periods of storage, one manufacturer states that the article, if properly stored and kept dry, will not deteriorate. Another states that practically 100 per cent efficiency was obtained from units stored in a proper manner, over quite a long period of time. Another states that the only difficulty experienced in the storage of rockets lay in the driving charge, in which changes of temperature will cause a parting of the compressed powder charge from the wall of the paper case, causing the rockets to operate too sharply. However, he states that after eight or nine years of storage ordinary commercial rockets have functioned perfectly, despite the fact that these rockets had not been protected with the wrapper envelopes, dipped in paraffin, as is now the practice.
As regards the manner in which the stored material should be packed, one manufacturer recommends packages of from 100 to 150 pounds each, piled 4, 5, or 6 cases high, avoiding the storage of loose or broken material.
As regards precautions with reference to moisture, temperature regulation, and light during storage, one manufacturer states that it is to be taken for granted that the storage magazine should be dry, and advises that no direct light be permitted, recommending that wire netting is desirable over glazed or colored glass windows.
Another states that they were accustomed to storing in wooden buildings, single story, of simple construction, unheated and dry, and that no lights or windows were used.
Another manufacturer states that the essential factor is a weather-tight, dry building. He makes no attempt to regulate temperature, nor the moisture, with any form of desiccator.
As regards the size of units stored in any one place at a time, one manufacturer stores from 50,000 to 100,000 pounds and claims that up to 200,000 pounds can be stored safely.
Another manufacturer is accustomed to storing from six to seven carloads at a given point.
As regard the character of storerooms, construction and ventilation, one manufacturer states that brick or stone is preferable as building material, or galvanized-iron walls with sawdust-filled spaces to maintain a cool temperature and to prevent sweating. The only ventilation recommended here is two cupolas in the roof or on the end walls, these cupolas being covered with fine-mesh screen, equipped with steel or iron protection. These buildings should have the dimensions 50 by 200 feet or 40 by 100 feet.
Another manufacturer states that the storage buildings they use are simply tight frame shells, with floors a short distance above the ground; they have no windows, but ventilators in the gable ends, and the roofs are of steel.
The experience of these manufacturers was largely confined to ordinary commercial fireworks, such as unprotected rockets and Roman candles, of which varying amounts were stored for different periods of time.