I've got a Holly vaporizer I am going to clean. Can I safely put in a molasses mix without danger to the aluminum or potmetal ventura and brass? What % molasses to water works best?
It is the acid in the molasses that does the 'action' That acid is not really strong enough to affect irons and steels.
Others may chime in differently, but my understanding is that the molasses will actually pit white metal if left soaking long enough, starting with the softest first, e.g. potmetal, then tins and zincs, then aluminums.
I put some old aluminum pistons in about a 15% solution of molasses. The wrist pins were rusted into them. I left them for 3 weeks. No discernable damage to the aluminum. Try your own test. You must have some scrap aluminum or potmetal around. I have NOT tried potmetal so can not speak to that.
I've used the molasses solution to get rusted pins out of brass and it never bothered the brass.
I've been experimenting with molasses on heavily rusted iron and originally started out using a 5 to 1 water to molasses ratio but found that a 3 to 1 ratio removes the rust in a much shorter time frame. With a severely rusted item (i.e. something that has sat out in the grove for 75 years) it can take four weeks or more to completely remove the rust.
I haven't tried de-rusting any lightly rusted items. A 5 to 1 ratio and a one week soaking would probably work for light rust.
I use feed-grade molasses (for use with livestock and attracting deer, etc.) purchased from the local farm supply store. On sale, the price drops to $5.00 a gallon.
After soaking, you will need to wash the item with water and a stiff brush. Also, there will be a slight yellow haze on the metal that can be removed with a quick "once over" on a wire wheel which will make the metal bright and shiny.
It is my understanding that molasses/water mixture will attack aluminum.
Die cast is mostly zinc with aluminum added. Might have some copper too with a long list of other trace elements as trash. It's best not to use any strong acid or strong alkali to clean it. Zinc will dissolve in either and cause heavy pitting. Stay in the 6-8pH range for cleaning solutions. If you can't do that, low-pressure blast it and burnish it to a shine.