"2.5XGB004"Retail price: $9.98
It can be used full strength and not diluted both as a dip for small parts as well as reacted to the surface with a brush.
In any case, it can be patted dry with a soft tissue, with very little black iron rub-off on normal steel and finished.
Note below, if you choose the kit scrolling down, you will get for 4 dollars more a complete kit around one of the bottles. Only individual bottles with nothing else can go USPS first class which will take a long time long distance this time of year.
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4 oz Pro 5-item Rugged Gun Blue Kit