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Decorating Defects - their cause and cure

Defects in Gilding

While gilding demands a high degree of skill on the part of the operative, and consequently many defects which occur are due to lack of experience of craftsmanship, others can be directly traced to the employment of cheap and inferior leaf, frequently of foreign origin. The importance of using only first-class English gold leaf made by a reputable firm, cannot be over-emphasised, if satisfactory results are to be obtained.
Joints Showing.-This is nearly always traceable to the use of poor­quality leaf, which either contains an excess of alloy or has not been properly beaten, and is so thin in the centre as to be nearly transparent.
To reduce the joint marks to a minimum, take care that the right stage of tackiness is reached and lay the leaves all one way, overlappmg each other by about one-eighth of an inch; then dab them carefully with a pad of cotton wool in the direction which will best close the joint.
Allow some hours to elapse before cleaning off the skewings, and do this in the opposite direction from that in which the leaf was laid, in order to prevent the edges from rubbing up.
Lack of Lustre.-This is probably due to the use of japanners' gold size instead of old oil gold size; the former has the advantage of drying very much more rapidly, but the degree of lustre which results from its employment cannot be compared with that which old oil gold size provides.
Applying the leaf before the size is sufficiently dry is another potential cause of this defect.
Tarnlshlng.-When this really occurs, it can be put down to a defect in the leaf, probably because it contains too much alloy, such as silver and copper; on the other hand, gold leaf is sometimes accused of having become tarnished when, in reality, exposure to the elements has given it a surface deposit of dirt. Before making a complaint, therefore, it is as well to examine it closely to determine whether the discoloration goes right through the leaf; a clean piece of soft linen, moistened in a weak solution of spirits of salts and rubbed very gently on the surface, is an effective way of testing this.
Gold Leaf Failing to Adhere.-When this occurs, it can almost in­variably be put down to the operative having waited too long before applying the leaf so that the size has become too hard. It takes some little experience to decide when the right stage of tackiness has been reached, but if anything beyond a light and even pressure is required to make the leaf adhere, it is safer to resize.
Cissing.-When the size cisses in glass gilding, a very likely explanation is that the hairs of the tip have been allowed to brush against the surface of the size. This may seem relatively unimportant, yet to pick up the leaf, the tip must be greasy, and the least trace of grease on the size is sufficient to cause trouble. Moreover, not only may the size be affected by the tip, but the latter may collect sufficient size to prevent it from releasing the leaf, which will consequently be spoilt.
Cracking.-When gold leaf cracks it will, in most cases, be found that japanners' gold size has been used and that the cause of the trouble is similar to that which leads to the cracking of paints, varnishes, and enamels -a difference in the rate of contraction of the ground coat.
Gold Leaf Flaking from Glass.-When leaf flakes from a shop window, framed sign, or similar position, the trouble can nearly always be attributed to lack of adequate ventilation. The condensed moisture which accumulates as a result of this condition affects the mordant, which is a water size, and weakens its binding power. Expansion or contraction of the glass, which will occur with a change of temperature, will be quite sufficient to cause the leaf to loose its hold.
So long as the conditions primarily responsible continue, the risk of the gold peeling will remain, and the only radical cure is to improve them. The obvious treatment, if it is possible, is the provision of apertures above the glass to allow the hot air to disperse.
Cloudiness in Water Gilding.-This is due to too thick a coating of isinglass size between the leaf and the surface of the glass on which it is applied. It often happens, on vertical work, that in sizing one portion of the glass, the size runs down on to another and dries unnoticed, so that when the operative sets to work on the lower portion it receives a double coating of sIze.
To eliminate any risk of this, the gilder should keep a jar of warm water and a clean soft pad or brush handy, and go over the lower part on which runs may have occurred.