Rosin

For other uses, seeRosin (disambiguation).

Rosin(/ˈrɒzɪn/), also known ascolophonyorGreek pitch(Latin:pix graeca), is a solid form ofresinobtained frompinetrees and otherplants,mostlyconifers,primarily through heating fresh liquid resin to vaporize thevolatileliquidterpenecomponents. Used widely in various industries and arts, rosin appears as a semi-transparent, brittle substance that ranges in color from yellow to black and melts at stove-top temperatures. Rosin consists mainly ofresin acids,especiallyabietic acid,and is soluble inalcohol,ether,benzeneandchloroform.

A cake of rosin, made for use by violinists.

In addition to industrial applications such in as varnishes, adhesives, and sealing wax, it is crucial for musicians who play bowedstring instrumentsto enhance bow grip, and it provides grip in various sports and activities. Rosin also serves as an ingredient in medicinal and pharmaceutical formulations and can causecontact dermatitisoroccupational asthmain sensitive individuals. It is anFDAapproved food additive.

The name "colophony" originates fromcolophonia resina,Latin for "resin fromColophon"(Ancient Greek:Κολοφωνία ῥητίνη,romanized:Kolophōnía rhētínē),an ancientIoniccity.

Properties

Pharmaceutical rosin

Rosin isbrittleandfriable,with a faint piny odor. It is typically aglassysolid, though some rosins will formcrystals,especially when brought into solution.The practical melting point varies with different specimens, some being semi-fluid at the temperature of boiling water, others melting at 100 to 120 °C (212 to 248 °F). It is very flammable, burning with a smoky flame, so care should be taken when melting it. It is soluble inalcohol,ether,benzeneandchloroform.

Rosin consists mainly ofabietic acid,and combines with causticalkalisto form salts (rosinatesorpinates) that are known asrosin soaps.In addition to its extensive use insoap making,rosin is largely employed in makingvarnishes(including fine violin varnishes),sealing waxand variousadhesives.It is also used for preparing shoemakers'wax,for pitchinglagerbeercasks,and numerous other purposes such as providing backing surfaces to tin ware, copper ware, or even silver and gold vessels when em Boss ing or engraving them. Its relatively low melting point, and firm solid form allows liquid rosin to be poured into the vessel, and when cooled allows em Boss ing or engraving of the vessel without deforming the vessel - even if it has a skin which is quite thin. Afterwards, the object can be reheated in an oven, and the rosin poured out for reuse. Any remaining rosin film can easily be rinsed away with alcohol or other solvents.

Rosin is also sometimes used as internal reinforcement for very thin skinned metal objects - like silver, copper or tin plate candlesticks, or sculptures, where it is simply melted, poured into a hollow thin-skinned object, and left to harden.

Prolonged exposure to rosin fumes released during soldering can causeoccupational asthma(formerly calledcolophony diseasein this context) in sensitive individuals, although it is not known which component of the fumes causes the problem.

The type of rosin used with bowed string instruments is determined by the diameter of the strings. Generally this means that the larger the instrument is, the softer the rosin should be. For instance,double bassrosin is generally soft enough to bepliablewith slow movements. A cake of bass rosin left in a single position for several months will show evidence of flow, especially in warmer weather.

Prolonged exposure to rosin, by handling rosin-coated products, such aslaser printeror photocopying paper, can give rise to a form of industrialcontact dermatitis.

Uses

Structure ofabietic acid,a component of rosin

Rosin is an ingredient inprintinginks,photocopying and laser printing paper,varnishes,adhesives(glues),soap,paper sizing,soda,solderingfluxes,andsealing wax.

Rosin can be used as aglazing agentinmedicinesandchewing gum.It is denoted byE numberE915. A relatedglycerol ester (E445)can be used as anemulsifierinsoft drinks.Inpharmaceuticals,rosin forms an ingredient in several plasters and ointments.

In industry, rosin is afluxused insoldering.Thelead-tinsoldercommonly used in electronics has 1 to 2% rosin by weight as a flux core, helping themoltenmetalflow and making a better connection byreducingthe refractory solidoxidelayer formed at the surface back to metal. It is frequently seen as a burnt or clear residue around new soldering.

A mixture ofpitchand rosin is used to make a surface against whichglassispolishedwhen making optical components such aslenses.

Rosin is added in small quantities to traditionallinseed oil/sand gap fillers ( "mastic" ), used in building work.

When mixed with waxes and oils, rosin is the main ingredient ofmystic smoke,a gum which, when rubbed and suddenly stretched, appears to produce puffs ofsmokefrom the fingertips.

Rosin is extensively used for itsfriction-increasing capacity in several fields:

• Players ofbowed string instrumentsrub cakes or blocks of rosin on their bow hair so it can grip the strings and make them "speak", or vibrate clearly.Occasionally, substances such asbeeswax,gold,silver,tin,ormeteoric ironare added to the rosin to modify itsstiction/frictionproperties and the tone that can be produced.Powdered rosin can be applied to new hair, for example with a felt pad or cloth, to reduce the time taken in getting sufficient rosin onto the hair. Rosin is often reapplied immediately before playing the instrument. Lighter rosin is generally preferred for violins and violas, and in high-humidity climates, while darker rosins are preferred for cellos, and for players in cool, dry areas.There are also specific, distinguishing types forbasses.
• Violin rosin can be applied to thebridgesin other musical instruments, such as thebanjoandbanjolele,in order to prevent the bridge from moving during vigorous playing.
• Ballet,flamenco,andIrish dancersare known to rub the tips and heels of their shoes in powdered rosin to reduce slippage on clean wooden dance floors or competition/performance stages. It was at one time used in the same way infencingand is still used as such byboxers.
• Gymnastsandteam handballplayers use it to improve grip.Rock climbershave used it in some locations.
• Olympic weightliftersrub the soles of their weightlifting boots in rosin to improvetractionon the platform.
• It is applied to thetracksurface at the starting line ofdrag racingcourses to improve traction.
• Bull ridersrub rosin on their rope and glove for additional grip.
• Baseball pitchersandten-pin bowlersmay use a small cloth bag of powdered rosin for better ball control. Baseball players sometimes combine rosin with sunscreen, creating a very sticky substance that allows far more grip on the ball than the rosin alone will; the use of such a substance is a violation ofMajor League Baseballrules.
• Rosin can be applied to the hands in aerialacrobaticssuch asaerial silksandpole dancingto increase grip.

Anetchingplate covered with powder resin

Other uses that are not based on friction:

• Fine artuses rosin fortemperaemulsionsand as painting-medium component foroil paintings.It is soluble in oil ofturpentineand turpentine substitute, and needs to be warmed.
• In aprintmakingtechnique,aquatintrosin is used on theetchingplate in order to create surfaces in gray tones.
• Inarchery,when a newbowstringis being made or waxed for maintenance purposes, rosin may be present in the wax mixture. This provides an amount of tackiness to the string to hold its constituent strands together and reduce wear and fraying.
• Dog groomersuse powdered rosin to aid in removal of excess hair from deep in the ear canal by giving the groomer a better grip to grasp the hairs with.
• Some brands offly paperuse a solution of rosin and rubber as the adhesive.
• Rosin is sometimes used as an ingredient in dubbing wax used infly tying.
• Rosin is used hot to de-encapsulateepoxyintegrated circuits.
• Rosin can be mixed with beeswax and a small amount of linseed oil to affix reeds to reed blocks in accordions.
• Rosin potatoes can be cooked by dropping potatoes into boiling rosin and cooking until they float to the surface.

Rosin and its derivatives also exhibit wide-ranging pharmaceutical applications. Rosin derivatives show excellent film forming and coating properties.They are also used for tablet film and enteric coating purpose. Rosins have also been used to formulate microcapsules and nanoparticles.

Glycerol,sorbitol,andmannitolesters of rosin are used aschewing gumbases for medicinal applications. The degradation andbiocompatibilityof rosin and rosin-based biomaterials has been examinedin vitroandex vivo.

Production

Various types of rosin for violins, violas and cellos

A piece of rosin for violins, violas and cellos

Rosin is the resinous constituent of theoleo-resinexuded by various species ofpine,known in commerce as crudeturpentine.The separation of the oleo-resin into theessential oil(spirit of turpentine) and common rosin is accomplished bydistillationin large copperstills.The essential oil is carried off at a temperature of between 100 °C (212 °F)° and 160 °C (320 °F), leaving fluid rosin, which is run off through a tap at the bottom of the still, and purified by passing through straining wadding. Rosin varies in color, according to the age of the tree from which the turpentine is drawn and the degree of heat applied in distillation, from anopaque,almost pitch-black substance through grades of brown and yellow to an almost perfectly transparent colorless glassy mass. The commercial grades are numerous, ranging by letters from A (the darkest) to N (extra pale), superior to which are W (window glass) and WW (water-white) varieties, the latter having about three times the value of the common qualities.

Tall oilrosin is produced during the distillation of crude tall oil, a by-product of thekraft papermaking process.

When pine trees are harvested "the resinous portions of fallen or felled trees like longleaf and slash pines, when allowed to remain upon the ground, resist decay indefinitely."This "stump waste", through the use ofdestructive distillationor solvent processes, can be used to make products including rosin. This type of rosin is typically calledwood rosin.

Colophony (rosin) from themaritime pine

Because the turpentine and pine oil from destructive distillation "become somewhat contaminated with other distillation products",solvent processes are commonly used. In this process, stumps and roots are chipped and soaked in the light end of the heavynaphthafraction (boiling between 90 and 115 °C (194 and 239 °F)) from a crudeoil refinery.Multi-stage counter-currentextractionis commonly used. In this process, fresh naphtha first contacts wood leached in intermediate stages, and naphtha laden with rosin from intermediate stages contacts unleached wood beforevacuum distillationto recover naphtha from the rosin, along withfatty acids,turpentine, and other constituents later separated throughsteam distillation.Leached wood is steamed for additional naphtha recovery prior to burning for energy recovery.After the solvent has been recovered, "the terpene oils are separated byfractional distillationand recovered mainly as refined turpentine, dipentene, and pine oil. The nonvolatile residue from the extract is wood rosin of rather dark color. Upgrading of the rosin is carried out by clarification methods that generally may include bed-filtering orfurfural-treatment of rosin-solvent solution. "

On a large scale, rosin is treated by destructive distillation for the production of rosin spirit, pinoline androsin oil.The last enters into the composition of some of the solid lubricatinggreases,and is also used as anadulterantof other oils.

The chief region ofrosin productionincludesIndonesia,southernChina(such asGuangdong,Guangxi,Fu gian,YunnanandJiangxi), and the northern part ofVietnam.Chinese rosin is obtained mainly from theturpentineofMasson's pinePinus massonianaandslash pineP. elliottii.The latter species is native to the southeastern U.S., but is now widely planted in tree plantations in China.

TheSouth Atlanticand easternGulf statesof theUnited Statesis a second chief region of production. American rosin is obtained from the turpentine oflongleaf pinePinus palustrisandloblolly pineP. taeda.InMexico,most of the rosin is derived from live tapping of several species ofpinetrees, but mostlyPinus oocarpa,Pinus leiophylla,Pinus devonianaandPinus montezumae.Most production is concentrated in the west-central state ofMichoacán.

The main source of supply inEuropeis theFrenchdistrict ofLandes,in thedepartmentsofGirondeandLandes,where themaritime pineP. pinasteris extensively cultivated. In the north of Europe, rosin is obtained from theScots pineP. sylvestris,and throughout European countries local supplies are obtained from other species of pine, withAleppo pineP. halepensisbeing particularly important in theMediterraneanregion.

Health effects

The fumes released during soldering have been cited as a causative agent ofoccupational asthma.The symptoms also includedesquamationofbronchialepithelium.

See also

• Copal
• Amber

References

• Kent, James A.Riegel's Handbook of Industrial Chemistry(Eighth Edition). Van Nostrand Reinhold Company (1983).ISBN0-442-20164-8.

External links

• Kotapish, Paul (November–December 2001)."Sticky Business: How Rosin Is Made".Strings.