Hello all. First time poster. Want to add to the topic of Mill Scale.
I weld horseshoe art. I stated welding horseshoes as a way to teach my grandchildren how to weld.
Removal of all the mill scale on a horseshoe is to key to getting the best adhesion of paint to the horseshoes. When the horseshoe object is welded, such as a pumpkin, it is no longer easy to further clean around the horseshoes. Thus, time spend on initial mill scale removal is time well spent.
To remove the mill scale from new horseshoes I soak them in white vinegar. Although muriatic acid is quick, I do not like to use muriatic acid as it is extremely caustic and disposal is not easy. I, therefore, trade time for ease of disposal by using white vinegar. I also only use this set-up outside. One can read online many horror stories caused by muriatic acid fumes from soaking metals inside a shop.
I place the new horseshoes in a container with a lid. I use containers with lids so the contents can remain outside even if raining. I stack the horseshoes with popsicle sticks between the horseshoes so the vinegar will reach the entirety of each shoe. I soak the new horseshoes in white vinegar for two days, then rotate the location of the popsicle sticks, and let soak another two days. It can be left longer. I found four days total works best for me.
I then rinse each horseshoe with fresh water and toss into a pail of water and baking soda. I let the horseshoes soak for a few minutes. The water-baking soda bath is complete when there are no bubbles forming in the bath. Then I pressure wash the horseshoes at 1500-1800 psi. You will be amazed at the amount of crud the pressure washer removes!
I then hang the horseshoes over the side a (trash) can and let dry. The horseshoes will begin to oxidize, however, not very much. I have let them dry for as long as a couple of days before the following final step.
To finalize, I tumble the horseshoes in a modified cement mixer using medium grade coal slag. I tumble about 15-20 horseshoes for 2 hours. The amount of horseshoes tumbling at one time depends on the size of the horseshoes. After tumbling the horseshoes will generally not exhibit any oxidation. The modification to the cement mixer is changing the slotted paddles to solid paddles. With solid paddles in the mixer the horseshoes will not get hung-up while tumbling. To date I have cleaned the mill scale from about 800 horseshoes, ranging in size from pony shoes to walkers.
TB
