Are one piece lids approved for water bath canning? I was wanting to switch to one piece plastisol lined canning lids for jam- the continuous thread type not lug. are they acceptable for products sold at farmer's markets or at our farm store?
Single piece lids have not been adequately tested for use in home canning by the National Center for Home Food Preservation. In addition one piece lids are not typically used for water bath canning. It can be difficult to apply the correct amount of force to the lid so that it is not over or under tightened.
With that said there is no specific language in the Oregon Farm Direct Law that prevents producers making products under this licensing exemption from using one piece lids for naturally acidic foods like jams and jellies or for lacto-fermented foods. The requirements for these products is that they be processed in a "clean, healthful, and sanitary manner". If you are making acidified foods like pickles, chutneys, or salsas these must be processed using a published process and recipe. All of the current published processes that have been approved for use under the OR farm direct law recommend using a two piece lid.
If you need more information about the farm direct law as it applies to producer processed products this publication from OSU Extension is helpful.