Problems with Lead Based Soldering

The Problems with Lead Based Soldering

  NASA Project Mercury Astronaut, the late Virgil “Gus” Grissom, may have been the first American to know just how small planet Earth really is, as compared to the vastness of outer space.  Flying aboard “Liberty Bell 7”, Grissom was launched from Cape Canaveral, Florida for a short but important manned space flight on July 21, 1961. 

        Grissom who was a former U.S. Air Force test pilot, was the second American in space but he was the first one to have a “large” 14 x 20-inch window to view the Earth below.   Truly it was a window on the world.  

        For many, the beginning of the space program also marks the start of what we now call “the information age”.  Today, no part of the world is inaccessible to our view and as we now know, immune from the consequences of our actions. 

        Thanks in part to man’s conquest of space, we know more today than at any other time in history, about man’s effect on our global environment.   But even in fairly recent times, that was not the case.

        I was 11 years old when Gus Grissom flew into space in 1961.  As a child growing up in the ‘50s and ‘60s the world was much different than it is today.  My father worked in the plumbing industry back then and I can remember him routinely working with Lead and other hazardous materials on a daily basis.  In fact, if you look up the word “Plumber” in the dictionary, one of the common definitions is that of  “Lead Worker”. 

        In the 1950s, Lead based material was routinely used to seal drinking water pipes and sewer drains.   There were no caution labels on these hazardous products and workers rarely ever used protective breathing masks or clothing. 

 Toys for Tots   

        On occasion, my father would even fashion toy soldiers out of molten lead, by pouring the hot liquid into molds much the way fishing sinkers are made.  After cooling, the lead soldiers were extracted from the molds and given to my brother and I for play “toys”. 

        In today’s world, the thought of handing a small child a piece of Lead to play with would probably be grounds for a court action.  Of course back in the 50’s my father didn’t know about the hazards associated with lead poisoning and if there were concerns about the product, it was not widely disseminated.  Today the use of Lead has been banned in the food and beverage industries but it is still widely used in electronics.

 A Long History   

        The ancient Egyptians produced lead and other important metals like gold and silver as early as 5000 BC.  In the Roman era, lead was used for coinage, jewelry and other everyday items including the production of Lead pipes for the transportation of water.  Remarkably, many of these water systems have been found virtually intact by modern day archeologists’.  One important property of lead is its reluctance to breakdown over time.  And as we will see later, that is also part of the problem.

        Lead has many properties that make it attractive to countless industries, especially electronics.  Lead is malleable; it has a low melting point, good electrical and thermal conductivity and is available in large quantities with a relatively low cost.  As a common metal Lead has a mass density only rivaled by Gold.  Lead is Heavy! 

        Lead’s widespread use in the electronics industry has been well documented as a shielding material for X-rays, RF and Audio, as well as a sound insulator in professional studio applications.   Lead/acid batteries power our cars, and lead based solder compounds help form tight durable electrical connections. 

  The Hazards   

        Scientific data now shows the cumulative effect that Lead has on the bodies’ central nervous system and the formation of red blood cells.  We also know that children are especially vulnerable to high toxicity levels and less likely to tolerate abuse.   But although today the problems with Lead are no longer in doubt, clearly the questions about Lead’s affect on the environment and on those who come in contact with it, have been around nearly as long as Lead itself. 

        Remarkably as far back as the 1st century BC some Roman engineers suggested using clay instead of Lead pipes for water systems.  This opinion was not based on a long-term government sponsored study, rather the engineers noticed that many lead workers (Plumbers) were getting sick and lacked vigor.  They concluded quite rightly, that if the Plumbers were suffering from exposure to lead, others who came in contact with it would probably get sick as well!  In spite of these revelations and other more recent warning signs Lead was continually used in many industries until recent times.

        Great strides have been made in the health and safety field in the last few decades.  As a result, a total ban on the use of Lead additives in paint and gasoline took effect in the 1970’s and ‘80s, and according to current Federal Law, Lead may no longer be used in or around drinking water or in the food industry.  The effects of reducing lead pollution in the atmosphere and the water supply are beginning to pay off in the form of a cleaner environment. 

        In electronics manufacturing however, lead has continued to be used and will be around for some time to come.  Lead of course, is one of the major components in solder.  Many in the electronic industry have lobbied for exemptions to the banning of lead based solder products on various grounds and as of yet manufacturers have managed to stave off government regulation.  Currently, electronics industry associations have begun to implement voluntary bans on the use of Lead with the goal of total elimination in the near future. 

        While the amount of Lead found in the circuitry of your average VCR or home stereo would at first thought appear to be insignificant, think about how many of these products get tossed away every year!  All this stuff ends up in someone’s “back yard”, there to remain forever, like the Roman water pipes of old!  Recycling used electronic gear to extract small amounts of Lead is extremely expensive.   So, far better to eliminate the problem at the source by reducing or eliminating Lead during manufacture.

 Most at Risk  

        As Technicians, most of our exposure to Lead comes when we repair or build equipment using Lead based solder.  Sadly, even if there was an outright ban on any further use of lead solder in the electronics industry, many potential problems would remain whenever we repair older equipment that still has Lead solder forming the joints.   In addition to all this, significant health problems can arise from simply breathing in the solder smoke.  So, lets take a closer look at how solder is actually used in the electronic industry. 

        Soldering is the act of joining two metallic surfaces by the use of low melting point metal alloys.  Modern electronic Solder is not made entirely of Lead but rather a mixture of elements.  Because pure Lead has poor mechanical strength Tin is added to Lead to make the solder connection stronger.  In addition, the Tin / Lead mixture has a lower melting point than using Lead alone, a prime consideration in electronics.  60/40 solder contains 60% Tin and 40% Lead. 

        To promote uniform solder flow (wetting), and also for joint cleaning, a Flux material is added to the 60/40 mix. The smoke that is released when solder is melted comes from heating the flux.  For electronics a non-corrosive Rosin-resin flux is used.  Although Rosin is a “natural” product made from pine trees (pine tar) its use along with other chemicals added to the flux make the solder fumes naturally acidic and potentially harmful to man.  Even naturally produced products can be harmful!

 The Smell of Smoke  

        The residual lead content found in solder smoke is negligible and the most immediate concern with solder smoke comes from breathing the flux fumes.  For many people prolonged exposure to solder smoke and fumes may cause headaches, nausea, eye irritation or occasional coughing.  For an unlucky few, chronic bronchitis and occupational asthma can be the outcome.  It’s estimated that approximately one out of five unprotected industry workers will suffer this fate.  While removing Lead from solder is a long-term plus for your body and the environment, protecting users from breathing in solder fumes will yield an immediate benefit in the form of a healthier workspace.  Simply put, you are being exposed to the chemicals found in the solder flux every time you smell the smoke.

 Another Warning    

        Perhaps in some ways we have become desensitized to the vast number of warnings, which exist for all of the products we use on a daily basis.  Common sense generally prioritizes these hazards into some likelihood of immediate danger or concern.   While this attitude is probably human nature it may lull one into a false sense of security.  An equal cause for concern should be reserved for the health problems generated by the small, seemingly insignificant abuses, which become cumulative over long periods of time.   In many ways these problems are the easiest to control. 

        As with cigarette smoking, the effects of breathing in solder smoke and working around lead based solder may not become apparent for many years.  So the fundamental question then is “How much direct contact with lead and smoke inhalation is too much?”  Not being a doctor or a scientist I will personally err on the side of caution.  Common sense suggests that if you have the ability to control your exposure to a hazardous material why not do it?

        After handling lead based solder, simple washing of hands prior to continuing work or eating will help protect the user from most of the hazards associated with touching the Lead product.   Thinking back, I’m sure neither my brother or I, ever washed our hands voluntarily for any reason, let alone after playing with lead soldiers.   For the utmost protection against airborne contaminants while soldering, you might choose to control your breathing environment by the use a full-face respirator designed to trap these hazards.  While wearing a respirator may offer the worker an improved level of protection, it seems impractical at best.  Besides, a respirator only protects the wearer.  It does not protect the guests who visit your shop or work area.   Enter another partial solution.

     Hakko model 493  Fume Ejector   

     © property of Hakko Company    

 Suck It Up   

        Experts in the field of occupational health & safety will tell you that many great safety inventions have gone unused because of either cost or the difficulty of use.  Even though the control of airborne pollutants has been available for some time, only recently has the technology become affordable for small industry and the hobbyist.  The product shown at the right and listed below offer a reasonable compromise for both the home and shop. 

        The similarly designed ZEPHYRTRONICS Air Plus model ZT-4 and the HAKKO model 493 both offer control of your personal breathing environment while soldering.  Rather than having the solder smoke billowing into the air around you, (and potentially others as well) these fume ejectors direct the smoke away from the worker, and filter it in the process! 

        According to the product literature the filters trap approximately 80% of the airborne smoke.  While 80% is not total control, that’s 80% less than you are probably breathing now!  The filter material is made of a high density foam mixed with activated charcoal.  Both commercially made smoke ejectors are well designed and may be ordered through several electronic suppliers including JAMCO Electronics, Mouser and the TECHNI-TOOL Company.  The units sell for approximately 50 to 150 dollars and replacement charcoal filters are also available from the catalogs.  With average use, one filter will last several months.

 What Price, Protection   

        Now, I realize that 50 to 150 dollars will buy a lot of other things including lots of new shop toys, but before you dismiss this safety devise out of hand as being too costly, let me offer a more cost effective alternative for you do-it-yourselfers. 

        While the commercial smoke ejectors are very well made and worth every penny if you do a lot of construction and repair, a reasonable substitute can be fabricated right in any home work shop.  After all, when you examine the commercially made units, a smoke ejector mainly consists of a very good quality filter system and a fan to suck in the fumes!   My “Knock-Off” version of this devise is shown at left and below. 

        With the home made unit, a small “muffin” fan scrounged from an old computer (before it hit the landfill) was outfitted with the same replacement filters used for the commercial grade units.  A metal shroud around the unit helps to direct and control the air flow.  Rather than make a shroud from scratch, an 8 inch metal cake pan purchased at a local discount store did the job nicely.

        Most of the parts for this device were found around the shop, but even if you bought all of the parts involved here, the total cost of fabricating your own smoke ejector might run about $20.00 dollars.  Replacement filters are priced at approx. 5 each for $25.00.  If you build several smoke ejectors for the home and workplace, the cost of buying the filters becomes even more affordable.  With the intermittent soldering done by many of us, one filter might last a year or more.  A small price to pay to protect your health and that of your co-workers and family. 

        While I purchased a commercially made unit for my workplace shop, the knock-off works almost as well and I’ve decided to dedicate it for those occasional repair jobs around the house.  By suggesting that you build the knock-off I don’t want to take anything away from the professionally made items.  But I know that there are some of you who will choose NOT to protect yourselves simply because of the “high” cost, and that would be a shame.  So, buy it or build it, there’s no excuse not to improve the air around you while working solder.

 Chances Are…   

        Will working with Lead based solder and breathing solder fumes affect your long term health?  No one can predict the future with 100% certainty.  Looking back, my father worked with many hazardous materials through most of his life and he was a heavy smoker for over 40 years, but through it all he remained in relatively good health until he died of heart failure at age 84. 

        Gus Grissom, was in excellent health and one of the first 7 men to be chosen as an Astronaut for America’s new space program.  In 1967 he was tragically killed at age 41 when a launch pad electrical fire consumed his Apollo I capsule.  Some would call that bad luck, but as a test pilot, Grissom knew the risks involved and accepted them as part of the job.  My father and other workers of his era didn’t know about many of the risks involved with their jobs.  In retrospect I think he was lucky.

        The risks taken by the early NASA pioneers  helped to make life safer for all those who followed in the space program, as well as giving us a new perspective on our world.  We as technical people should learn from past mistakes in the same way a fledgling space program learned from the Apollo I tragedy. 

        Thanks in part to the space program, we now know that pollution is not a one nation problem but rather a matter of global concern.  Mankind has more resources to draw on than ever before in history and we know more about man’s affect on the water we drink and the air we breath.  With all this knowledge about the health risks of breathing solder smoke why not listen to the warnings.  I would like to think that we are smarter today than we were in the old days, at least we don’t give children Lead toy soldiers to play with anymore.

        Protect yourself and everyone around you!


        Mercury I & II were both unmanned flights which tested rocket performance and guidance control.  Navy Pilot Alan Sheppard was the first American to fly in space when his Mercury III mission, was launched on April 18, 1961.  His capsule was nicknamed “Freedom 7”.   Sheppard died of natural causes in 1998 at the age of 74.

    NASA  ©    

        After a fiery re-entry sequence, Gus Grissom’s Friendship 7 capsule splashed down in the Atlantic Ocean off Florida’s eastern seaboard. 

        Navy divers quickly entered the water near the spacecraft and began to deploy a floatation device around the capsule in order to stabilize it.  But without warning, the escape hatch aboard Liberty Bell – 7 opened prematurely and seawater began to fill the capsule.  Grissom struggled to exit the craft and was rescued by the divers and safely brought back aboard the ship.   The Liberty Bell 7 capsule however soon filled with seawater and sank to the bottom of the ocean. 

        In 1999, after a 12 year search, a team headed up by veteran deep ocean explorer Curt Newport, found the Liberty Bell – 7 capsule, at a depth of 15,600 feet in the Atlantic Ocean off Florida.  Locating the remains of the nine foot long spacecraft at such an extreme depth, was literally like finding a needle in a haystack.  The Capsule was raised from its nearly three mile depth on July 20, 1999, one day shy of 38 years after it sank to the bottom of the ocean.  

        After an extensive effort to restore the capsule, Liberty Bell – 7 is now on permanent exhibit at the Cosmosphere and Space Center in Hutchinson, Kansas.



You may also like...