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Gudgeons & Pintals
$160.00 the set
#8 x 1" Planking Screws
Brass vs. Bronze
I have found that many novice builders (and even some professionals)
do not know the difference between brass and Bronze. Worse yet some of
the larger retailers of marine supplies and a few of the smaller manufacturers
are now praying in this fact. The are now selling "Bronze" fittings that
are really made of brass and counting on the fact that most people don't
know the difference. A few use a "Red Brass" that looks like Bronze but
many are now even using a "Yellow Brass" which is a very low copper, high
By definition Brass is an alloy of Copper and Zinc (and usually lead). Bronze is an alloy of Copper and Tin. This may not appear that important a difference but it really is.
First: Bronze is much stronger and more corrosion resistant than brass.
Second: Bronze is harder and more abrasion resistant than brass.
Third: As brass deteriorates is creates an oxide (a grey white powder - zinc oxide). Zinc oxide is acetic and will attack the lignum in wood. Once the lignum is gone the wood fiber is open to rot.
Are there any good sides to brass? Yes, but only for the manufacturer not the end user. Brass melts at a lower temperature and therefore used less enegry to melt. It machines and polishes much easier than Bronze and therefore the price to make a fitting from it is lower. Also, it goes away much more quickly and therefore the customer will have to purchase replacement parts much sooner. (It allows the manufacturer to have a built in supply of repeat customers.)
How do you know the difference or if the supplier is telling the truth? There is not such thing as just "Bronze". There are a great many different alloys of Bronze. Each one has different alloying elements and was designed for a specific purpose. (Just the way that you would never use the same wood to built all the parts of a boat you should never use the same alloy of Bronze to make all the fittings.) Different fittings should be made from different alloys of Bronze depending on the intended use of the fitting. Unfortunately all the fittings that you see in the mega marine stores are made from the same alloy of Bronze (really brass) which was chosen on the basis of how little it cost and not how good it was for a particular application.
For general recognition, Bronze will be a richer, more golden color than brass which is usually a yellow color. If there is any doube in your mind try an easy test. Using the smallest drill bit that you have drill a small hole in an unimportant area of the fitting and look at the metal turnings that come out. If they are long and stringy the fittings is probably Bronze. If the turnings are small (like snow flakes) then the metal is probably brass and even more probably a leaded brass.
The best thing that you can do however, is to ask the manufacturer or the retailer for precise information of the alloy of brass/Bronze that the fittings is made from. They should be able to give you the alloy name, CDA alloy number, the mechanical, chemical, and physical properties, and reference the ASTM or SAE specifications. If you find a manufacturer or retailer that hesitates to do this or can't do this, don't just walk away from this source - run.
Unfortunately some of the pictures that have appeared on the web site recently show that some of the Haven builders have used brass instead of Bronze. It is really a shame to put so much work into a project and ruin the whole thing by using fittings made from an inferior metal that will end up causing the wood to rot.
On the 23rd of September my own Herreshoff boat turned 83 years old. (She is the one on the home page of my web site.) All of her fittings are original, they are made of Bronze, and they still work fine. If Nat Herreshoff had made them of brass (perish the thought) instead of Bronze my boat would be on her seventh or eighth set by now.
If anyone that is building a Haven wants specific information on Copper base alloys such as the brasses and the Bronzes please feel free to give me a call any time.