These are custom black low head socket cap screws we supply to an offroad automotive product manufacturer. We have a revolving blanket purchase order arrangement with next day deliveries of the parts from the individual releases. Measuring 1/4-20 X 1 to standard IFI specifications, these low head socket cap screws are made in plain grade 5 steel material with black electroplated zinc finish for corrosion resistance. A standard nylon thread locking patch is applied as the final part of the process to get the parts ready for use.
As a rule of thumb, combining black zinc and nylon patch is NOT recommended because the parts are heated during the patch application process and the head is at the same time ran through the conveyor system – this causes discoloration and slight imperfections around the head, which can be seen in the photos shown here. Our customer is aware of this and due to the specific application in his product he is willing to accept this downside risks. We would definitely not recommend this combination for anyone planning to use the parts in a very visible portion of their product, especially if the sides of the head are exposed as well.