Does bronze de-zincify the same as brass? If it doesn't, could you try heating a sample and seeing if it turns pink?

Rob

In marine useage, the terms brass and bronze can be rather vague. A propellor shaft could well be naval or admiralty brass which can also be called tobin bronze, although it contains very little tin. Items referred to as bronze could well be an aluminium bronze, common for propellors, or manganese bronze.

All of these materials are strong and highly resistant to sea-water corrosion.

I have a prop shaft someone gave me, a lovely piece of yellow metal 1" diamter and five foot long. Looks nice and yellow like brass. But try to hacksaw a piece off and then machine it in the lathe and it is tough as anything so I have always assumed it's bronze of some sort. Definitely does not cut like nice soft brass.

As Noel says, it doesn't make any difference. I use it for general purpose work where either metal would do the job.

There's a simple chemical test for Tin described here.

Although the chemicals are available (Patio cleaner is Hydrochloric Acid, Zinc from Batteries and Potassium Permanganate from a Chemists), many of these old chemical tests require 'laboratory technique' and experience. Worth practising on lead-free electrical solder which is almost pure Tin to be sure the blue fluorescence is recognised.

If Tin is detected the metal is probably a Bronze. There is a fly in the ointment because a propeller is probably made of Admiralty Brass, which is 1% tin, less than a true Bronze (at least 10%), but maybe enough to confuse the test.

Of all the alloys, Brasses probably have the widest range of properties. Brasses with a high percentage of Zinc are so soft and crumbly as to be useless, whereas at the other end of the scale it's hard and tough, with pretty much everything in between. A dash of lead makes it machinable, Aluminium makes it stronger, and Iron harder and so forth. Cartridge Brass is malleable, others are good for forging, casting or rolling. Brass is my favourite metal, but some of it a pig, I'm not sure how useful the Brass in a second-hand propeller will be, but give it a try.

Dave

"That lovely piece of yellow metal"

Check it with a magnet, slightly magnetic? Alluminium Bronze.

Regards Ian.

An friend who worked for a company that did a lot of work machining bronze and got me a lot of off cuts,once told me that one way of identifying bronze/brass was that brass can be annealed ,bronze cannot be annealed, I did try annealing a piece of bronze and it would not anneal like brass or copper does,though I do not know if this applies to all type of bronze. Aluminium bronze is slightly magnetic,our local scrap merchant keeps a magnet handy for testing.

My go to reference for all things coppery is copper.org

To demonstrate …Here’s a search for ‘magnetic’ : **LINK**

https://www.copper.org/search.html?q=magnetic&submit=Search

MichaelG.