I promised some more info on the molasses rust removal treatment so here it is.

Sulphated molasses has been used to remove rust from iron and steel for centuries. Possibly ever since the first drunken pirate dropped his flintlock in some on a Caribbean island as molasses is a byproduct of sugar cane.

According to a PhD Chemist friend the sulphur creates a weak organic acid. This acid does not attack the base metal as do the acids many of us are familiar with; sulphuric, muriatic (diluted hydrochloric), phosphoric (naval jelly).

The molasses must be the sulphated variety which is usually found in feed and grain stores as a component of horse feed. It is sold in 55 gallon drums but the stores will pour into your or their 5 gallon pail. Cost is roughly $15 for 5 gallons.

The other ingredient is water.

Ratios of 3 and 4 parts water to 1 part molasses work well. Less concentration will also work but takes more time.

The mixture will attack aluminum so do not use any for the container. Steel, cast iron and plastic are fine as long as they are clean. Start with warm to hot water and mix in the molasses slowly, making sure it is completely dissolved. Heat speeds up the rust cleaning process also so plan accordingly with the container selection.

During 90 degree summer days a block will be finished in 10-14 days; a bit less for heads. Sheet metal, small parts about 5-10 days.

The mix will often remove thin flaking paints but it has no effect on oil, grease, dried crud, etc. A commercial hot tanking would be ideal but is often not convenient. I use various solvents and a pressure washer as the alternative.

The concoction creates a rather nasty looking crud on the surface; it will also get quite ripe so dont do this in the garage next to the wifes car or laundry machines.

After 3-4 days to a week, remove the item, scrape off or pressure wash the crud and skim the top layer in the container. You will have to experiment with the process the first time or two to get a feel for whats involved in a particular enviroment. A covered container is best but I've had decent results in even an open cast iron watering trough.

Ive gone into the mix with bare hands at times but I suggest a pair of cheap dishwashing gloves.

The useful life is until it doesnt work any longer. Cover it until needed again and top off any evaporated water. For instance, I've used one drum load for 5 blocks over a period of about 7 months. One guy forgot about a set of flatheads and left them in a barrel for 5 months, no damage.

Disposal can be down the drain or in the garden since it is enviromentally friendly. For garden or lawn dilute with more water as it can burn roots; it is a powerful fertilizer. It also seems to keep root eating grubs away.

Besides blocks, heads, intakes, exhaust manifolds; Ive cleaned straight axles, wishbones, wire and steel wheels, Model T sheet metal, tools and all sorts of other odds and ends.
It also does a good job on carbs but dont leave them in very long; Check daily. The same for general automotive potmetal once the chrome is stripped with a cyanide solution.

Blocks and heads will look like they were just cast, all waterjacket scale is gone.

Since the cleaned parts are virgin metal they will flash rust quickly in a hot moist area. Wrap, prime, oil as needed.

The 1926 Model T coupe hotrod Im building was a basket case body; rust and rot everywhere and too fragile to even media blast. I broke it down to individual small parts (the body is comprised of many small bolted together parts, virtually no welding) and dunked. Then I cut, formed and rolled pieces as needed and hammer welded in place. There are almost no replacement panels available.

There are many ways to dissolve rust, some very fast and dangerous. Others are quite expensive. Molasses will not be for everybody, it is just an alternative that appeals to my desire to be frugal at times so I can spend on something I HAVE to buy.

Since I pecked this out over a few days I cant guarantee it makes much sense. Fire away with any questions or suggestions.