machinists & sheet metal guys use it, also called layout fluid, helps to see scribe lines on bare metal (as shown on above metal parts). I must caution, it will be some pricey stuff to use as a guide coat if you are buying it retail. I got it from a "thrift" store, and it appears to be items from the local Navy base that were donated as they had expired shelf life. I paid less for it than what Walmart gets for their cheap spray paint, so to me it was worth trying. If you have to pay full price, it may not be as appealing..