The common shirt type frock is made from the same pattern as the common shirt, except that the frock is made a little longer, and usually from a slightly heavier material. As you can see, the collar shape varied with the maker. Shirt pattern shown here from: Tidings from the 18th Century By Beth Gilgun. This is a good book with more clothing patterns and information on a variety of 18th century items.
Patrón e Instrucciones para confección de Blusa Llanera
Molde de costura para una blusa de verano que viene perfecto para confeccionar la Blusa con Volados Llanera para bailar Joropo Venezolano...