Discussion of deterioration problems of Ryder's paintings centers upon the painter's techniques, both <i>peindre au premier coup</i> and the traditional indirect application of paint. Crackling and varnish slides showed up even during Ryder's lifetime, a result of inherent vice. Some problems have taken more time to appear. Specific instructions in regard to storage and environmental maintenance of the surviving paintings are given. General problems of deterioration which are characteristic of paintings are listed; a glossary of deterioration terms relating to paint film, varnish, and ground is also provided. Ryder also used incompatible materials; layers were also not allowed to dry thoroughly between applications of coatings.