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Quality of Brass in Old vs. New Screws

01/20/2014 12:33 PM

My son has been restoring an old house (about 80 to 90 years old). In the process of refinishing the brass hardware he has discovered that the old, original brass screws are much stronger than modern-made replacement screws. Asking around, I found that apparently it is common knowledge that modern brass screws are not as strong as old ones. I am wondering why. Are modern alloys inferior to those used 100 years ago? If so, is it because manufacturers are trying to save money with cheaper metal? Has recycling introduced tramp metals that have degraded properties? Or is it possible the old brass is stronger because of 100 years or age-hardening?

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#1

Re: quality of brass in old vs. new screws

01/20/2014 12:38 PM

Yes many things get harder as they age, copper, brass, wood....

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#4
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Re: quality of brass in old vs. new screws

01/20/2014 1:16 PM

getting up in the morning.....

but seriously, metal does not just get harder just laying around doing nothing, but, they may work harden from usage, (some people call it crystalize, but that the wrong terminology).

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#5
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Re: quality of brass in old vs. new screws

01/20/2014 1:22 PM

Actually some metals and alloys do get harder while sitting around doing nothing. It it due to precipitation-hardening which takes place very slowly at ambient temperatures.

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#6
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Re: quality of brass in old vs. new screws

01/20/2014 1:34 PM

Metallurgy is not my strong suit, but I never thought about the environment. As far as Precipitation hardening this would come into account with changes in solid solubility with temperature.

Stand corrected.

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#12
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Re: quality of brass in old vs. new screws

01/20/2014 4:25 PM

BS

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#14
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Re: quality of brass in old vs. new screws

01/20/2014 4:51 PM

sorry to disagree,

Brass is an alloy that is made with cupper (copper) and merely zinc. Second of this goes through a mere precipitation cycle.

Why (alu) cast blocks of engines use(d) to be in all weather, sometimes for years?

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#15
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Re: quality of brass in old vs. new screws

01/20/2014 5:35 PM

Okay maybe it wasn't beryllium that is or was a more common impurity that came from processing one of the ores.

I too am not a metallurgist but I do know they put an effort into trying to separate very old brass components form the newer stuff and someone pays good money for it for some reason.

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#16
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Re: quality of brass in old vs. new screws

01/20/2014 8:59 PM

The reply was actually for the abbreviation BS, delivered by answer 14 as I recall. Zinc is added with copper for easy machining. My wife is engineer metallurgist and handed me this:

Perhaps it might be of some help.

Brass Alloys

Alloy

Composition and Use

Admiralty brass30% zinc and 1% tin, used to inhibit dezincification
Aich's alloy60.66% copper, 36.58% zinc, 1.02% tin, and 1.74% iron. Corrosion resistance, hardness and toughness make it useful for marine applications.
Alpha brassLess than 35% zinc, malleable, can be worked cold, used in pressing, forging, or similar applications. Alpha brasses have only one phase, with face-centered cubic crystal structure.
Prince's metal or Prince Rupert's metalalpha brass containing 75% copper and 25% zinc. Named for Prince Rupert of the Rhine and used to imitate gold.
Alpha-beta brass or Muntz metal or duplex brass35-45% zinc and is suited for hot working. It contains both α and β' phase; the β'-phase is body-centered cubic and is harder and stronger than α. Alpha-beta brasses are usually worked hot.
Aluminium brasscontains aluminium, which improves its corrosion resistance. Used for seawater service and in Euro coins (Nordic gold).
Arsenical brass contains an addition of arsenic and frequently aluminium and is used for boiler fireboxes.
Beta brass45-50% zinc content. Can only be worked hot producing a hard strong metal that is suitable for casting.
Cartridge brass30% zinc brass with good cold working properties. Used for ammunition cases.
Common brass, or rivet brass37% zinc brass, standard for cold working
DZR brassdezincification resistant brass with a small percentage of arsenic
Gilding metal95% copper and 5% zinc, softest type of common brass, used for ammunition jackets
High brass65% copper and 35% zinc, has a high tensile strength and is used for springs, rivets, screws
Leaded brassalpha-beta brass with an addition of lead, easily machined
Lead-free brass as defined by California Assembly Bill AB 1953 contains "not more than 0.25 percent lead content"
Low brasscopper-zinc alloy containing 20% zinc, ductile brass used for flexible metal hoses and bellows
Manganese brass70% copper, 29% zinc, and 1.3% manganese, used in making golden dollar coins in the United States
Muntz metal60% copper, 40% zinc and a trace of iron, used as a lining on boats
Naval brass40% zinc and 1% tin, similar to admiralty brass
Nickel brass70% copper, 24.5% zinc and 5.5% nickel used to make pound coins in the pound sterling currency
Nordic gold89% copper, 5% aluminium, 5% zinc, and 1% tin, used in 10, 20 and 50 cts euro coins
Red brassan American term for the copper-zinc-tin alloy known as gunmetal, and an alloy which is considered both a brass and a bronze. Red brass usually contains 85% copper, 5% tin, 5% lead, and 5% zinc. Red brass may be copper alloy C23000, which is 14-16% zinc, 0.05% iron and lead, and the remainder copper. Red brass also may also refer to ounce metal, another copper-zinc-tin alloy.
Rich low brass (Tombac)15% zinc, often used for jewelry
Tonval brass (also called CW617N or CZ122 or OT58)copper-lead-zinc alloy
White brassbrittle metal containing more than 50% zinc. White brass may also refer to certain nickel silver alloys as well as Cu-Zn-Sn alloys with high proportions (typically 40%+) of tin and/or zinc, as well as predominantly zinc casting alloys with copper additive.
Yellow brassAmerican term for 33% zinc brass
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#17
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Re: quality of brass in old vs. new screws

01/20/2014 10:12 PM

Nice chart. GA. I vote that the new brass screws are from China and they have too much lead content. We went through that issue with brass fittings used in the water industry. NSF actually tested many brass fittings and recalled many pumps with brass ends. It cost the pump industry big time. The lead was leached out of the fitting and into the water supply. Private wells were particularly affected by lead content. I am not sure if screws with high lead content would be less hard but that is my guess.

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#21
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Re: quality of brass in old vs. new screws

01/21/2014 1:32 PM

Thanks for the brass chart; I copied it. Thank your wife too.

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#22
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Re: quality of brass in old vs. new screws

01/21/2014 1:45 PM

My pleasure, thank you all for the appreciation. The problem with the brass screws I ran into it too when almost permanently working on our old sailboat that has the whole interior screwed together with these.

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#7
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Re: quality of brass in old vs. new screws

01/20/2014 1:37 PM

Yeah I think they call it precipitation hardening, anybody who has worked with copper tubing knows that when in new shiny condition, it's extremely pliable...but left laying around it gets stiffer....trying to bend old 7/8" copper tubing on a changeout will make a believer out of any skeptic...

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#2

Re: Quality of Brass in Old vs. New Screws

01/20/2014 12:54 PM

I'm not sure about that. Even today you can buy different grades of brass screws, and I'm not sure the the brass colored stuff you get at Home Depot, would even be considered true brass.

http://everestmfgco.com/Brass_Screws_Fasteners.htm

I'm thinking that people rarely order the high grade brass, today, and that maybe all of the old brass would be considered high grade.

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#10
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Re: Quality of Brass in Old vs. New Screws

01/20/2014 3:22 PM

My Uncle used to talk about red brass and yellow brass. Red brass was the stronger alloy, yellow was cheaper and not as strong. Yellow brass was slightly less weather/water resistant than red. Most of what we see today (H Depot & the like) is yellow brass.

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#3

Re: Quality of Brass in Old vs. New Screws

01/20/2014 1:06 PM

I'd say that the quest to save money (or, rather maximize profits) probably accounts for the weakening of modern day "brass" hardware.

There's "brass" and then there's brass "alloy" hardware that mostly has only the color in common.

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#25
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Re: Quality of Brass in Old vs. New Screws

01/24/2014 1:51 PM

Maybe they are just trying to stay in business. It is hard competing with the 3rd world and now they ( 3rd world ) are competing against themselves. I usually do not pay for quality unless I must.

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#8

Re: Quality of Brass in Old vs. New Screws

01/20/2014 2:40 PM

It could be that 80 to 90 years ago we didn't have this disposable culture. That the hardware was alloyed to last.

Today we have these big stores on every corner that we can run out to to get replacements.

80 - 90 years ago I doubt it. Most likely replacements came mail order and took weeks to get. Don't think many manufactures would do a very good business if their hardware failed like what we have today at these big hardware stores. Their purchasing agent is most likely one step up from the person that checks you out. And like the person that check you out it's all about price. Ever have a conversation with anyone of their so called associates. Have little knowledge of the product. It's questionable if you can find one that even knows where hardware is in the store.

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#20
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Re: Quality of Brass in Old vs. New Screws

01/21/2014 1:24 PM

Today we have these big stores on every corner that we can run out to to get replacements.

Unfortunately not true at all with some of the stuff I run into! Try to find a fillister head screws these days. Many don't even know what they are. How about screws when you DO NOT want Phillips head. Then there are the hex bolts with the high, domed heads. (Gee, even this spell check doesn't know about fillister. Wonder what it would do with something like Prony Brake?)

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#9

Re: Quality of Brass in Old vs. New Screws

01/20/2014 3:21 PM

Different alloys to make more profit save money. Zinc is a lot cheaper.

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#11

Re: Quality of Brass in Old vs. New Screws

01/20/2014 3:52 PM

My buddy that has the large scrap yard has commented many times that the old brass is of a different grade and metallurgical formulation than most of the modern brass. If I am recalling things right much of the old brass has more beryllium in it compared to today's brass.

I think it had to do with the base mineral stock they used back then being less refined and having more trace element impurities in them that were actually beneficial to the final products characteristics.

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#18
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Re: Quality of Brass in Old vs. New Screws

01/21/2014 5:03 AM

Beryllium is a poisonous metal and needs careful work procedures to prevent long term poisoning and serious health problems....

Maybe thats why it is not seen as often today.....

I found a reasonable explanation here:-

http://en.wikipedia.org/wiki/Beryllium#Precautions

Containing this:-

Approximately 35 micrograms of beryllium is found in the human body, but this amount is not considered harmful.[82] Beryllium is chemically similar to magnesium and therefore can displace it from enzymes, which causes them to malfunction.[82] Chronic berylliosis is a pulmonary and systemic granulomatous disease caused by inhalation of dust or fumes contaminated with beryllium;
either large amounts over a short time or small amounts over a long time can lead to this ailment. Symptoms of the disease can take up to five years to develop; about a third of patients with it die and the survivors are left disabled.

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#23
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Re: Quality of Brass in Old vs. New Screws

01/21/2014 2:51 PM

I'm not sure Beryllium is or was the correct element of compound that he was talking about relating to old brass.

As I said he does have some people who ask specifically for old brass regardless of what it was used for and they pay above and beyond normal clean sorted brass market value for it.

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#24
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Re: Quality of Brass in Old vs. New Screws

01/21/2014 11:43 PM

You mentioned it first, I only said it was dangerous!! It wasn't in the table if I remember correctly...

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#13

Re: Quality of Brass in Old vs. New Screws

01/20/2014 4:49 PM

One possibility, Doors and drawers was heavier back then, then they are today, so was the hardware used.

May have to go with the premium hardware.

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#19

Re: Quality of Brass in Old vs. New Screws

01/21/2014 11:37 AM

More than one factor may be coming into play.

.

Historical brass used in musical instruments is known to age harden. It is a precipitate hardening process related to impurities in historical brass.

.

The difference in strength might be more influenced by factors other than the alloy, like difference in the shape, and the way the manufacturer made the screws.

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