A limitation on the use of normal moiré technique may be the practical difficulties which can be encountered on coating the resist layers for the production of etched gratings. A description is given of a simple coating method which can be applied to any testpiece and which requires only a brush and some skill on the part of the operator.The method can also be used to coat resist layers suitable for the production of high frequency gratings of more than 1 000 lines/mm (25400 lines/in)