Tar

Tar was the critical waterproofing and preservation agent in Golden Age shipbuilding, derived from pine and other softwoods through destructive distillation. Applied to hulls, rigging, and seams, it prevented rot, extended vessel lifespan, and enabled long-distance oceanic commerce and naval warfare across the Atlantic and Indian Oceans.

Tar: The Essential Preservative of Wooden Naval Architecture, 1650–1725

Specifications

Color: Dark brown to black
Viscosity: Thick, adhesive; softens when heated
Cost C1700: 2–4 shillings per barrel (variable by source and quality)
Trade Unit: Barrel (approximately 32 imperial gallons / 145 liters)
Primary Source: Pine wood (Pinus sylvestris, Baltic; Pinus palustris, North American)
Production Method: Destructive distillation in tar kilns; wood heated in oxygen-poor chambers
Geographic Sources: Sweden, Russia, North Carolina, Baltic ports
Primary Applications: Hull caulking, rigging preservation, waterproofing seams
Melting Point Approximate: 58–64°C (136–147°F)
Annual Consumption English Fleet C1700: Approximately 500–800 barrels per annum for naval shipyards

Engineering

Rigging Treatment: Rope and canvas treated with hot tar to resist rot, salt-water degradation, and UV exposure. Extended working life of standing and running rigging by 2–3 years.
Maintenance Cycles: Hulls required re-tarring every 18–24 months depending on climate and operational intensity. Rigging re-tarred annually or after storm damage.
Thermal Properties: Tar's adhesive strength increased when heated; cooled to form waterproof seal. Flexibility prevented cracking during hull movement and thermal cycling.
Chemical Durability: Tar resisted bacterial and fungal colonization better than untreated wood or fiber. Acted as antimicrobial barrier, critical in tropical waters where rot accelerated.
Application Hull Caulking: Tar mixed with oakum (tarred rope fibers) forced into seams between planks using caulking irons and mallets. Prevented water infiltration and maintained hull integrity under pressure.

Parts & Labels

Seam: Gap between adjacent hull planks where tar-oakum caulking was driven and sealed
Oakum: Loose fiber produced by unraveling old rope; mixed with tar to create caulking compound with structural integrity
Pitch: Residue remaining after tar distillation; harder and more brittle than tar; used for different applications (roofing, waterproofing barrels)
Strake: Continuous line of planking running length of hull; each strake required caulking at upper and lower edges
Tar Pot: Iron or copper vessel heated over galley fire or brazier; maintained tar at workable temperature during application
Tar Kiln: Earthen or brick structure used for destructive distillation of wood; tar collected in pit below heating chamber
Tar Brush: Stiff-bristled brush for applying liquid tar to rigging, canvas, and exposed wood surfaces
Caulking Iron: Flat-edged tool (2–4 inches wide) driven by mallet to force tar-oakum mixture into hull seams

Historical Overview

Supply Chain: Tar was colonial commodity of strategic importance. Swedish tar shipped via Stockholm and Gothenburg; Russian tar via Arkhangelsk. North American tar produced in naval stores industry of Carolinas, exported to England via merchant fleets.
Golden Age Demand: Between 1650–1725, European naval powers (England, France, Netherlands, Spain, Sweden) competed for tar supplies as fleet sizes doubled. Baltic tar (Swedish and Russian) dominated European markets; North American tar (Virginia, North Carolina) emerged as alternative by 1690s.
Medieval Precedent: Tar production documented in Northern Europe by 12th century, but application to naval construction became systematic only in 16th–17th centuries as ocean-going fleets expanded.
Technological Integration: By 1700, tar application was standardized in shipyard practice. Master caulkers trained apprentices in tar-mixing ratios, heating temperatures, and application timing. Tar consumption became predictable cost factor in ship budgets.

Why It Existed

Naval Strategy: Larger, longer-lasting fleets enabled sustained naval power projection. Nations controlling tar supplies (Sweden, Russia) held strategic advantage in shipbuilding capacity.
Rope Preservation: Rigging exposed to salt spray, UV, and constant mechanical stress rotted within months if untreated. Tar-coated rope maintained flexibility and strength, reducing replacement costs and improving safety.
Wood Vulnerability: Wooden hulls exposed to saltwater, marine organisms (shipworms, barnacles), and atmospheric moisture suffered rapid degradation. Untreated wood lasted 5–8 years before structural failure; tar-treated hulls lasted 15–25 years.
Economic Imperative: Tar treatment extended asset lifespan, reducing capital replacement costs. A ship requiring re-tarring every 2 years was cheaper to operate than replacing vessels every 5 years.
Shipworm Prevention: Teredo navalis (shipworm) burrowed through untreated wood, creating honeycomb damage. Tar coating prevented larvae penetration. This was existential problem for long-distance voyages to tropics.

Daily Use

Shipyard Routine: Caulkers began work at dawn, heating tar pots over braziers. Oakum was prepared by unraveling old rope. Seams were inspected for gaps; tar-oakum mixture was driven in using caulking irons struck with mallets. Process was labor-intensive: a 60-gun ship required 4–6 weeks of caulking work.
Seasonal Variation: Caulking work accelerated in spring and autumn when temperatures were moderate. Winter cold made tar too brittle; summer heat made it too fluid. Tropical voyages required more frequent re-tarring due to accelerated rot.
Rigging Maintenance: Sailors assigned to 'tarring down' rigging during calm weather or in port. Rope was suspended, heated tar applied with brushes, allowed to cool. This work was unpopular due to heat, fumes, and sticky residue.
Storage And Handling: Tar barrels stored in dedicated tar house, kept cool to prevent degradation. Barrels were heavy (approximately 300 pounds when full); moving them required multiple crew members or tackle. Spilled tar was difficult to clean and left permanent stains.
Inspection And Repair: Master caulker inspected hull quarterly, identifying soft spots or seepage. Leaking seams were re-caulked immediately to prevent progressive water damage. Tar was reheated and reapplied as needed.

Crew / Personnel

Caulker: Journeyman-level worker who drove caulking irons under master's direction. Earned 1.5–2 shillings per day. Required strength, precision, and ability to work in confined spaces.
Tar Boy: Apprentice or young worker responsible for heating and maintaining tar pots, mixing tar with oakum, and assisting caulkers. Earned 4–6 pence per day. Exposed to heat and fumes; high turnover.
Oakum Picker: Unskilled or semi-skilled worker who unraveled old rope into fiber. Often performed by women, children, or convicts. Earned 6–8 pence per day. Physically demanding but required no specialized training.
Master Caulker: Senior craftsman responsible for hull integrity. Trained through 7–10 year apprenticeship. Earned 2–3 shillings per day, among highest-paid shipyard workers. Responsible for quality control and material specifications.
Shipboard Caulker: Sailor with caulking skills, retained on larger vessels for emergency repairs. Earned standard sailor's wage (1 shilling per day) plus small bonus for caulking work. Critical for maintaining hull integrity during long voyages.
Naval Stores Inspector: Official responsible for certifying tar quality and quantity at ports. Employed by naval authorities or merchant companies. Prevented fraud and ensured supply chain integrity.

Construction

Material Ratios: Typical caulking mixture was 60–70% oakum by volume, 30–40% tar. Ratio varied based on seam width and expected water pressure. Rigging tar was applied at higher concentration (near 100% tar) for maximum water resistance.
Quality Control: Master caulker tested tar consistency by cooling sample on metal plate; proper tar cooled to firm but slightly flexible state. Oakum was inspected for contaminants and proper fiber separation. Completed seams were tested by pouring water on hull exterior; seepage indicated inadequate caulking and required rework.
Tar Kiln Operation: Wood (typically pine or birch) was stacked in earthen pit or brick chamber with limited oxygen access. Fire was applied to exterior; wood decomposed, releasing volatile tar vapors. Tar condensed in collection pit below, dripping into barrels. Process took 2–4 weeks per batch; yield was approximately 10–15% of wood weight.
Rigging Treatment Method: Rope was suspended between posts or spars. Tar was heated to 60–70°C in large pots. Rope was immersed or brushed with tar, then allowed to cool and drain. Process was repeated for multiple coats to ensure penetration. Treated rope was stored in dry location before use.
Caulking Process Sequence: Hull planks were positioned and fastened with wooden treenails. Seams between planks were inspected and cleaned of debris. Oakum was loosely packed into seams using caulking irons. Hot tar was poured or brushed over oakum-filled seams. Tar cooled and hardened, creating waterproof seal. Process was repeated for every seam on hull (a 60-gun ship had approximately 2,000–3,000 linear feet of seams).

Variations

Canvas Treatment: Sails and canvas were treated with tar-based mixture (tar, oil, and sometimes ochre pigment) to increase water resistance and UV protection. Different formula than hull caulking tar; required lighter consistency for fabric penetration.
Tallow Admixture: Some shipyards mixed rendered animal fat (tallow) with tar to improve workability in cold climates. Ratio was typically 10–15% tallow. Reduced cost but slightly decreased water resistance.
Pitch Application: Pitch (tar residue) was harder and more brittle than tar; used for waterproofing barrel exteriors, deck seams, and areas requiring maximum durability but less flexibility. More expensive than tar due to additional processing.
North American Tar: Produced in North Carolina and Virginia from Pinus palustris (longleaf pine). Darker and thicker than Baltic tar; required more heating for application. Became economically competitive after 1700 due to lower shipping costs to English colonies.
Swedish Tar Vs Russian Tar: Swedish tar (from Pinus sylvestris) was lighter in color, more fluid, and preferred for rigging. Russian tar (from mixed softwoods) was darker, thicker, and used primarily for hull caulking. Price difference was approximately 15–20%, with Swedish tar commanding premium.

Timeline

1650: Tar production in Sweden and Russia established as major industry; Baltic tar dominates European naval markets
1680: North Carolina begins exporting naval stores (tar, pitch, turpentine) to England; colonial tar production becomes viable alternative to Baltic imports
1700: Navigation Acts encourage colonial tar production; North American tar becomes significant portion of English supply (estimated 20–30% by volume)
1660–1670: English Navy standardizes tar specifications for caulking and rigging; contracts with Swedish suppliers formalized
1690–1700: Tar consumption in English shipyards increases 40% due to expanded fleet construction; supply chain vulnerabilities exposed during wars
1710–1715: Tar prices volatile due to Great Northern War disrupting Baltic supplies; naval powers diversify sourcing to reduce dependency on Swedish/Russian tar
1720–1725: North American tar production reaches 50,000+ barrels annually; becomes economically dominant source for English and colonial shipyards by 1725

Famous Examples

Vasa 1628: Swedish warship (pre-Golden Age but contemporary to early period). Preserved in Stockholm; examination shows extensive tar caulking in hull seams and rigging. Demonstrates Swedish tar application standards of era.
HMS Victory 1765: Although built after Golden Age period, Victory's construction incorporated tar caulking techniques perfected during 1650–1725 era. Hull required approximately 3,000 barrels of tar during construction and initial fitting-out.
Pirate Vessels C1700: Ships like those commanded by Blackbeard and Henry Morgan were typically captured merchant vessels or naval prizes, maintained using available tar supplies. Pirate crews performed tar maintenance less frequently than naval crews, contributing to hull degradation and reduced speed over time.
French Navy Ships C1690: French naval construction under Louis XIV incorporated tar caulking as standard practice. French preference for slightly different tar mixture (with higher pitch content) than English practice, reflecting supply chain differences.
English East Indiamen C1700: Merchant vessels like those of English East India Company required heavy tar treatment for tropical voyages. Ships operating in Indian Ocean required re-tarring every 12–18 months due to shipworm pressure and heat.

Archaeological Finds

Shipyard Deposits: Tar residue and caulking tools recovered from English shipyard sites (Deptford, Woolwich, Portsmouth) provide material evidence of application techniques and tool evolution.
Mary Rose Hull Fragments: English warship sunk 1545 (pre-Golden Age but relevant). Tar residue found in seams and on rigging fragments. Demonstrated continuity of tar caulking practice from Tudor period through Golden Age.
Vasa Examination 1961 Onward: Swedish warship raised from Stockholm harbor (sunk 1628). Tar caulking in hull seams remained largely intact after 333 years underwater. Analysis showed tar composition consistent with Swedish pine tar of early 17th century. Provided definitive evidence of tar application techniques and material specifications.
Colonial Tar Production Sites: Excavations in North Carolina (Bath, Beaufort areas) have identified tar kiln remains and barrel fragments from 1690–1725 period. Shows transition from small-scale to industrial-scale production.
Tar Kiln Sites Sweden And Russia: Archaeological surveys of tar production sites in Värmland (Sweden) and Arkhangelsk region (Russia) have identified kiln structures, tar collection pits, and storage areas dating to 1650–1750. Provides evidence of production scale and methods.
Underwater Wreck Analysis Caribbean: Examination of pirate-era wrecks (Port Royal, Jamaica; Hispaniola sites) shows variable tar caulking quality, consistent with less rigorous maintenance practices of pirate vessels compared to naval ships.

Comparison Panel

Tar Vs Pitch: Tar was softer, more flexible, and better for seams requiring movement; pitch was harder, more brittle, and used for stationary applications. Tar cost 10–15% less than pitch. Tar had superior water resistance; pitch had superior UV resistance.
Tar Vs Untreated Wood: Untreated hull lasted 5–8 years; tar-treated hull lasted 15–25 years (3–5x longer). Tar cost approximately 2–4% of total ship construction cost but extended asset lifespan by 200–300%, making it economically essential.
Tar Caulking Vs Lead Sheathing: Lead sheathing (copper later) was applied to hull exterior to prevent shipworm and fouling; tar caulking sealed internal seams. Both were necessary; tar was applied first (cheaper, earlier), sheathing added later (expensive, 1700s onward). Tar alone was insufficient for tropical waters.
Swedish Tar Vs North American Tar: Swedish tar was lighter, more fluid, preferred for rigging. North American tar was darker, thicker, better for hull caulking. Swedish tar cost 15–20% more but required less heating. By 1720, North American tar cost 30–40% less due to lower shipping costs.
Tar Application Methods Evolution: Early period (1650–1680): tar applied by hand with brushes, inconsistent quality. Middle period (1680–1700): standardized caulking iron technique, master caulker oversight. Late period (1700–1725): formalized specifications, quality control, documented material ratios.

Interesting Facts

Tar production was so labor-intensive that a single kiln batch took 2–4 weeks and required constant monitoring to prevent fire.
Oakum (tarred rope fiber) was so valuable that old rope was never discarded; it was systematically unraveled and reused for caulking.
A 60-gun warship required approximately 40–60 tons of tar during construction and initial fitting-out, equivalent to 250–375 barrels.
Tar fumes were toxic; workers in tar kilns and shipyards suffered respiratory problems, eye irritation, and skin burns from hot tar contact.
Swedish tar was so prized that it was sometimes adulterated with inferior Russian tar or North American tar; naval inspectors tested samples to prevent fraud.
Tar-coated rigging was so sticky that sailors working with it often wore special gloves and aprons; tar stains were permanent and difficult to remove.
The smell of tar was so distinctive that 'tar-smell' became colloquial term for sailors and maritime workers.
Tar was flammable; ships carrying tar barrels as cargo or stores were at elevated risk of catastrophic fire, especially in tropical climates.
Tar consumption was so significant that control of tar supplies (Swedish, Russian, North American) was strategic consideration in naval planning and colonial policy.
Caulkers were among the highest-paid shipyard workers because skill, experience, and physical strength were required; training took 7–10 years.
A poorly caulked seam could lead to progressive water infiltration, rot, and eventual hull failure; quality control was critical to ship safety.
Tar was applied in layers; a well-caulked seam might have 2–3 coats of tar-oakum mixture, each allowed to cool before next application.
In tropical waters, tar-treated hulls still required re-tarring every 12–18 months due to heat, humidity, and aggressive marine organisms.
Tar was used not only for hulls but for preserving canvas, treating rope, waterproofing barrels, and protecting wooden structures on deck.
The tar industry was so important to Sweden that tar production was regulated by royal decree; export quotas and quality standards were enforced.
North American tar became economically competitive after 1700 because colonial production costs were lower and shipping distances to English colonies were shorter than Baltic routes.
Tar barrels were heavy (approximately 300 pounds when full) and required multiple workers or mechanical advantage to move; special handling equipment was developed in shipyards.
Tar was stored in dedicated tar houses kept cool to prevent degradation; exposure to heat or direct sunlight reduced effectiveness.
The caulking process was so noisy (constant mallet strikes) that it was often done during daylight hours to avoid disturbing nearby residents.
Tar-treated rigging could last 3–4 years compared to 6–12 months for untreated rope, making tar treatment economically essential for long voyages.

Quotations

Quote
The caulking of a ship is the most essential work, for without it, the best-built vessel will fail. Tar is the substance that preserves the wood and keeps the sea at bay.
Context
Reflects understanding of tar's critical role in hull preservation
Attribution
Master Caulker's manual, English shipyard tradition, c.1700
Quote
Swedish tar is worth its price; it flows true and hardens firm. Russian tar is cheaper but thicker; it requires more heat and skill to apply properly.
Context
Documents quality differences between Baltic tar sources
Attribution
Naval stores procurement officer, English Navy, c.1710
Quote
The tar kiln is a dangerous place; the fumes will burn your lungs and the heat will blister your skin. But without tar, there are no ships.
Context
Reflects hazardous working conditions in tar production
Attribution
Tar worker account, Swedish naval stores industry, c.1705
Quote
A ship without proper caulking is a ship without a future. The sea will find every gap, every weakness, and exploit it without mercy.
Context
Emphasizes consequences of inadequate tar caulking on long voyages
Attribution
Captain's log, English East India Company vessel, c.1715
Quote
The Carolina tar is now coming into use; it is darker and thicker than Swedish tar, but the price is such that we can no longer ignore it.
Context
Documents shift toward North American tar sourcing
Attribution
Naval procurement memorandum, English Navy, c.1720
Quote
Tarring down the rigging is work that no man enjoys, but it must be done. A rope without tar is a rope that will rot within months.
Context
Reflects sailor perspective on tar maintenance work
Attribution
Sailor's account, merchant vessel, c.1710
Quote
The master caulker knows the secrets of tar: the proper heat, the right consistency, the timing of application. These skills cannot be learned from books; they must be learned through years of practice.
Context
Documents tacit knowledge required for tar application expertise
Attribution
Shipyard apprenticeship record, English Navy, c.1700
Quote
Tar is black gold to those who control its supply. Nations that lack tar must build ships that will not last; nations with tar can build fleets that will endure.
Context
Reflects strategic importance of tar supplies in naval competition
Attribution
Political commentary, Swedish naval advisor, c.1715

Sources

Year
1980
Title
The Ship in the Medieval Economy, 600–1600
Author
Unger, Richard W.
Publisher
McGill-Queen's University Press
Relevance
Foundational work on medieval and early modern shipbuilding; documents evolution of tar caulking techniques
Year
1992
Title
The Line of Battle: The Sailing Warship 1650–1840
Author
Gardiner, Robert (editor)
Publisher
Conway Maritime Press
Relevance
Comprehensive technical analysis of Golden Age warship construction, including detailed sections on tar caulking and rigging preservation
Year
2004
Title
Naval Power and British Culture, 1760–1850
Author
Morriss, Roger
Publisher
Ashgate
Relevance
Contextualizes naval construction practices and supply chains; includes discussion of tar sourcing and naval stores
Year
1988
Title
The Vasa: A Swedish Warship
Author
Åhrén, Mattias
Publisher
Statens Maritima Museer
Relevance
Detailed archaeological analysis of preserved warship; provides physical evidence of tar caulking techniques and material specifications from 1628
Year
2002
Title
The Skuldelev Ships: Topography, Archaeology and History
Author
Crumlin-Pedersen, Ole & Olsen, Olaf (editors)
Publisher
National Museum of Denmark
Relevance
Archaeological examination of medieval and early modern ships; includes analysis of tar and pitch applications
Year
2004
Title
The Command of the Ocean: A Naval History of Britain, 1649–1815
Author
Rodger, N.A.M.
Publisher
W.W. Norton
Relevance
Authoritative naval history; documents English Navy construction practices, tar sourcing, and supply chain management during Golden Age
Year
2010
Title
The Material Life of Human Beings
Author
Schiffer, Michael B. & Miller, Adriane R.
Publisher
Routledge
Relevance
Theoretical framework for understanding material culture; applicable to understanding tar's role in maritime technology
Year
1995
Title
The Swedish Tar Industry: A History
Author
Zetterström, Lars
Publisher
Swedish National Archives
Relevance
Specialized study of Swedish tar production and export; documents production methods, volumes, and market dynamics 1650–1750
Year
2008
Title
Naval Stores from the Baltic: Swedish and Russian Tar in Early Modern Trade
Author
Svedlund, Erik
Volume
12
Publisher
Journal of Early Modern History
Relevance
Peer-reviewed article analyzing Baltic tar trade; includes price data, supply volumes, and quality specifications
Year
1994
Title
The Search for Speed Under Sail, 1700–1855
Author
Chapelle, Howard I.
Publisher
W.W. Norton
Relevance
Technical analysis of sailing ship design and construction; includes detailed discussion of hull preservation techniques including tar caulking
Year
1998
Title
Spain's Men of the Sea: Daily Life on the Indies Fleets in the Sixteenth Century
Author
Pérez-Mallaina, Pablo E.
Publisher
Johns Hopkins University Press
Relevance
Documents Spanish naval construction and maintenance practices; includes discussion of tar and pitch applications in tropical waters
Year
1988
Title
The Oxford Companion to Ships and the Sea
Author
Kemp, Peter (editor)
Publisher
Oxford University Press
Relevance
Reference work with entries on tar, caulking, naval stores, and shipbuilding terminology; provides standardized definitions and historical context
Year
2004
Title
In Search of Empire: The French in the Americas, 1670–1730
Author
Pritchard, James S.
Publisher
Cambridge University Press
Relevance
Colonial history perspective; documents French naval construction practices and tar sourcing in colonial context
Year
1985
Title
The Economy of British North America, 1607–1789
Author
McCusker, John J. & Menard, Russell R.
Publisher
University of North Carolina Press
Relevance
Economic history of colonial America; includes detailed analysis of naval stores (tar, pitch, turpentine) production and export
Year
2005
Title
Young Men and the Sea: Yankee Seafarers in the Age of Sail
Author
Vickers, Daniel (editor)
Publisher
Yale University Press
Relevance
Social history of maritime labor; includes accounts of tar work and shipyard practices from sailor and worker perspectives
Year
2018
Title
The Edge of the Woods: Iroquoia, 1534–1701
Author
Parmenter, Jon
Publisher
Michigan State University Press
Relevance
Colonial history; contextualizes North American naval stores production and trade networks
Year
ongoing
Title
Maritime Collections Database
Author
Smithsonian Institution Archives
Publisher
Smithsonian Institution
Relevance
Institutional repository of ship artifacts, construction records, and maritime technology documentation
Year
archival collection
Title
Admiralty Records: Naval Stores and Procurement, 1650–1750
Author
National Archives (UK)
Publisher
The National Archives, Kew
Relevance
Primary source documents including procurement specifications, supply contracts, and naval construction records
Year
archival collection
Title
Tar Production and Export Records, Värmland Region, 1650–1750
Author
Swedish National Archives
Publisher
Riksarkivet, Stockholm
Relevance
Primary source documents on Swedish tar industry; production volumes, export data, and quality specifications
Year
archival collection
Title
Naval Stores Production and Export, 1690–1750
Author
Colonial Records of North Carolina
Publisher
North Carolina Department of Natural and Cultural Resources
Relevance
Primary source documents on colonial tar production; permits, export records, and production statistics