How It's Made

CAPTIONS PAID FOR BY DISCOVERY COMMUNICATIONS, INC.

Narrator: TODAY ON "HOW IT'S MADE"...

CONGA DRUMS...

...METAL PLATING...

...AND BUTTONS.

THE CONGA DRUM MAY BE A STAPLE OF LATIN-AMERICAN MUSIC,

BUT IT WAS DEVELOPED FROM AN ANCIENT AFRICAN DRUM

MADE FROM AN ANIMAL SKIN

STRETCHED OVER A HOLLOW TREE TRUNK.

TODAY, THEY STRETCH THE HIDE

OVER A WOOD OR FIBERGLASS CYLINDER.

AS YOU'RE ABOUT TO SEE,

MAKING CONGAS TAKES PLENTY OF HANDS-ON SKILL.

THESE CONGAS ARE MADE OF ASH,

A WOOD THAT HAS GOOD ACOUSTICS.

THAT MEANS SOUND RESONATES OFF OF IT

RATHER THAN BEING ABSORBED INTO IT.

FIRST, THE DRUM MAKER CUTS THE CURVED SLATS

THAT WILL FORM THE DRUM'S BODY, CALLED THE SHELL.

HE TRACES A SLAT-SHAPED TEMPLATE

ON A RECTANGULAR PIECE OF WOOD.

THEN, USING A BAND SAW, HE CUTS ALONG THE TRACE LINE,

CREATING A CURVE ON THE OUTSIDE AND INSIDE SURFACES.

THEN HE MOVES TO A BENCH SAW,

A SAW WHOSE BLADE CAN BE ADJUSTED TO DIFFERENT ANGLES.

HE CLAMPS THE PIECE ONTO A TEMPLATE

AND ANGLES THE EDGE.

HE FLIPS THE PIECE OVER...

...AND ANGLES THE OTHER EDGE.

THE DRUM MAKER APPLIES CARPENTER'S GLUE TO BOTH EDGES

AND CLAMPS THE SLATS TOGETHER IN A CIRCLE

ON A SPECIALLY DESIGNED FORM.

THE NUMBER OF SLATS PER DRUM VARIES,

DEPENDING ON THE DIAMETER OF THE SHELL.

THE LARGER THE DIAMETER, THE LOWER THE CONGA'S SOUND.

THE GLUE DRIES IN 24 HOURS.

IT COMES OFF THE FORM

LOOKING LIKE THIS BONGO SHELL, BUT TALLER.

THE DRUM MAKER NOW MOUNTS THE DRIED SHELL ON A WOOD LATHE.

USING A TOOL CALLED A WOOD GOUGE,

HE SHEARS OFF ABOUT .2 OF AN INCH,

ROUNDING THE OUTSIDE OF THE SHELL.

THEN HE USES A SERIES OF WOODWORKING TOOLS

TO ADD DECORATIVE DETAILING.

ONCE THAT'S DONE, HE SMOOTHES THE SHELL'S SURFACE,

USING THREE PROGRESSIVELY FINER GRAINS OF SANDPAPER.

THEN HE EITHER LEAVES THE WOOD ITS NATURAL COLOR OR STAINS IT.

A THICK COAT OF OIL-BASED LACQUER PROTECTS THE WOOD

FROM BOTH DRYNESS AND HUMIDITY.

NOW FOR THE ESSENTIAL HARDWARE.

FIRST, SIDE PLATES MADE OF CHROME-PLATED STEEL.

THEIR JOB IS TO ANCHOR THE DRUM'S ANIMAL-SKIN HEAD.

THEY'RE BOLTED TO THE SHELL.

NEXT, THE DRUM MAKER FEEDS A STEEL STRIP

THROUGH A BENDING MACHINE.

ITS HIGH-PRESSURE ROLLERS CURVE THE STRIP,

FORMING THE DRUM'S RIM.

THEN HE RIVETS V-SHAPED STEEL PIECES ONTO THE RIM.

ELSEWHERE IN THE WORKSHOP,

THEY PREPARE THE COWHIDE THAT WILL BECOME THE DRUM'S HEAD.

FIRST THEY SOAK IT

IN A CORROSIVE BATH OF COLD WATER AND LIME.

THIS LITERALLY BURNS THE HAIR OFF THE HIDE.

AFTER TWO OR THREE DAYS,

THEY REMOVE THE SKIN AND SCRAPE OFF ANY STUBBORN HAIRS.

THEN THEY STRETCH IT OVER A CIRCULAR FRAME,

LEAVING IT TO DRY AT ROOM TEMPERATURE

FOR A COUPLE OF DAYS.

AFTER CHROME-PLATING THE RIM,

IT'S TIME FOR THE FINAL ASSEMBLY.

THEY STRETCH THE HEAD OVER THE SHELL

AND CLASP IT IN PLACE WITH THE RIM.

THEY HOOK THE V's TO THE SIDE PLATES,

THEN ADJUST THE TENSION TO TUNE THE INSTRUMENT.

THE LAST STEP IS TO TRIM OFF THE EXCESS SKIN.

NOW THE MUSICAL HANDIWORK CAN BEGIN.

Narrator: PLATING IS A LAYER OF METAL COATING AN OBJECT

MADE OF A DIFFERENT TYPE OF METAL.

THE PURPOSE CAN BE DECORATIVE, AS IN SILVER PLATING,

OR PRACTICAL.

WITH INDUSTRIAL PARTS, FOR INSTANCE,

ZINC OR CADMIUM PLATING

PREVENTS THE UNDERLYING METAL FROM RUSTING,

WHILE NICKEL OR CHROME PLATING PROTECTS AGAINST WEAR.

YOU CAN PLATE ALMOST ANY TYPE OF METAL.

LET'S FOLLOW SOME STEEL AEROSPACE PARTS

AS THEY'RE ABOUT TO BE PLATED WITH CADMIUM

TO MAKE THEM CORROSION-RESISTANT.

FOR THE PLATING METAL TO BOND PROPERLY,

THE STEEL SURFACE MUST BE FREE OF CONTAMINANTS

SUCH AS OIL AND GREASE.

WORKERS SUSPEND THE PARTS

OVER A VAT OF BOILING CHEMICAL SOLVENTS.

AS THE HOT VAPOR COMES IN CONTACT WITH THE COLDER METAL,

IT CONDENSES, DRIPPING DOWN INTO THE VAT

AND TAKING ANY CONTAMINANTS ALONG WITH IT.

THE REMAINING SOLVENT RESIDUES EVAPORATE,

LEAVING THE PARTS SQUEAKY-CLEAN AND DRY.

NEXT, A WORKER WEARING PROTECTIVE CLOTHING

SANDBLASTS THE PARTS WITH ALUMINUM OXIDE POWDER,

A STRONG ABRASIVE.

THIS ROUGHENS UP THE SURFACE

SO THAT THE PLATING METAL WILL ADHERE BETTER.

THE MOST COMMON PLATING METALS FOR INDUSTRIAL PURPOSES

ARE ZINC, CHROME, AND NICKEL.

THINK MOTORCYCLE PARTS OR SINK FAUCETS.

DECORATIVE ITEMS, ON THE OTHER HAND,

ARE MOST LIKELY TO BE PLATED IN TIN, BRASS, GOLD, OR SILVER.

TRADITIONAL TEA SETS, FOR INSTANCE,

ARE OFTEN MADE OF SILVER-PLATED COPPER OR ZINC.

THE PLATING PROCESS IS CALLED ELECTROPLATING

BECAUSE THE KEY IS ELECTRICITY.

THEY START BY TYING STRANDS OF COPPER WIRE

TO A COPPER SUPPORT FRAME.

COPPER IS THE BEST METAL FOR CONDUCTING ELECTRICITY.

THEN THEY ATTACH THE STEEL PARTS THEY'LL BE PLATING.

WHEN THEY HOOK UP THE SUPPORT TO AN ELECTRIC CURRENT,

ELECTRICITY WILL RUN FROM THE SUPPORT THROUGH THESE WIRES

RIGHT TO THE PIECES.

THEY DO THE ELECTROPLATING IN A TANK.

AFTER FILLING IT WITH WATER,

THEY ADD A HANDFUL OF CHEMICALS TO HELP CONDUCT ELECTRICITY,

BECAUSE WATER ALONE WON'T CONDUCT IT SUFFICIENTLY.

ALONG THE SIDES OF THE TANK, IN BAGS, ARE METAL BASKETS.

THEY CONTAIN BARS OR BALLS OF THE PLATING METAL --

IN THIS CASE, CADMIUM.

WORKERS CONNECT THE SUPPORT FRAME WITH THE STEEL PARTS

TO THE NEGATIVE TERMINAL OF AN ELECTRIC SOURCE --

THE BASKETS OF CADMIUM TO THE POSITIVE TERMINAL.

THEN, THEY SWITCH ON A STEADY D.C. CURRENT

NO STRONGER THAN SIX VOLTS.

THE ELECTRICITY DISSOLVES THE CADMIUM,

PLACING THE PARTICLES WITH A POSITIVE CHARGE.

THEY TRAVEL THROUGH THE WATER

AND ATTACH THEMSELVES TO THE NEGATIVE-CHARGED STEEL PARTS.

THIS CREATES A SMOOTH AND EVEN LAYER OF CADMIUM.

THIN PLATING REQUIRES JUST A FEW MINUTES IN THE TANK.

THICK PLATING, SEVERAL HOURS.

THEN WORKERS RINSE THE PARTS IN WATER FOR ABOUT A MINUTE

TO REMOVE THE CHEMICAL RESIDUES.

TO MAKE THE PARTS EVEN MORE RUST-RESISTANT,

WORKERS IMMERSE THEM IN A SERIES OF COMPOUNDS.

THIS TRIGGERS A CHEMICAL REACTION IN THE PLATING,

ENHANCING ITS ABILITY TO WITHSTAND CORROSION.

THIS REACTION, HOWEVER, CHANGES THE COLOR.

A FINAL RINSE IN HOT WATER,

AND THIS CADMIUM-PLATED STEEL AEROSPACE PART IS FINALLY READY.

FROM START TO FINISH,

THE PROCESS HAS TAKEN ABOUT 90 MINUTES.

TO PLATE WITH CHROME OR GOLD,

THEY HAVE TO USE A CHEMICAL COMPOUND

CONTAINING GOLD OR CHROMIUM.

THAT'S BECAUSE ELECTRICITY CAN'T DISSOLVE

SOLID CHROMIUM WELL ENOUGH,

AND IT CAN'T DISSOLVE SOLID GOLD AT ALL.

THE COMPOUND DISSOLVES IN THE BATH LIKE SALT,

BUT THEN SOLIDIFIES

ONCE IT REACHES THE OBJECT BEING PLATED.

METAL PLATING IS VERY DURABLE,

BUT IF SUBJECTED TO A LOT OF WEAR AND TEAR,

THE OBJECT WILL EVENTUALLY HAVE TO BE REPLATED.

Narrator: HAVE YOU EVER WONDERED WHY MEN'S BUTTONS

ARE TRADITIONALLY ON THE RIGHT SIDE OF A GARMENT

AND WOMEN'S ON THE LEFT?

LEGEND HAS IT THAT THIS ENABLED A MAN

TO UNBUTTON HIS COAT WITH HIS LEFT HAND

WHILE DRAWING A SWORD WITH HIS RIGHT.

WEALTHY WOMEN, MEANWHILE,

HAD THEIR BUTTONS SEWN ON THE LEFT SIDE

TO MAKE IT EASIER FOR THEIR RIGHT-HANDED MAIDS

TO DRESS THEM.

ONE WAY TO MAKE PLASTIC BUTTONS