Caulking (sealants)
Description
Any material used to fill or seal joints and openings. Ancient boats were found with fiber and wood fills, but later natural waterproofing materials, such as waxes and tars were also used. Oil-based caulking, or Putty, was composed primarily of Calcium carbonate or Lead white mixed with drying oils. Ntural rubbers and vulcanized rubbers also found there way into usage as sealants, adhesives and fills. The first elastomeric sealant, commercially developed in the 1950s, was composed of Polysulfide (Thiokol®). Butyl rubber sealants, also manufactured in the 50s, contained Talc, calcium carbonate, Polybutylene, Mineral spirits, and adhesion promoters. The first acrylic sealant, promoted in 1958, was a solvent curing product that included calcium carbonate, Silica, Solvent, and Plasticizer. Silicone sealants, introduced in the 1960s, are still the primary type that is used in museums for building display cases. These sealants often contain Fumed silica, calcium carbonate, ground Quartz, Carbon black, talc, and plasticizers. Polyurethane elastomers provide good abrasion resistance. Latex caulking, available in the late 1960s, eliminated the use of organic solvents. They typically contain a polymer emulsion (such as Polyvinyl acetate) in water with calcium carbonate, plasticizers, and other additives.
| Caulk/putty | Earliest use | Composition | Examples | Applications | Characteristics and Risks |
|---|---|---|---|---|---|
| Fibers/Wood | ancient times | boats | |||
| Wax | ancient times | vessels | becomes soft with heat | ||
| Tar | ancient times | boats | |||
| Oil-based caulk (sometimes lead-based putty) | 19th-20th c. | 10-15% Linseed oil with Calcium carbonate, red or White lead and sometimes other inorganic fillers (Talc, Alum, Asbestos) | Seal window to frame, fill defects in wood and metal; surround pipe joint | Lead compounds accelerate drying; some components are toxic | |
| Cement putty | Concrete | mortar | |||
| Gesso putty | Gelatin with Chalk | ||||
| Rubber (natural, vulcanized) | 19th c to WWII | gaskets, shock mounts, | waterproof, can crack due to ozone | ||
| Polysulfide | 1950s | Any synthetic rubber vulcanized with sulfur (styrene-butadiene, Polyisoprene) | Neoprene, Thiokol | o-rings, pipe linings, building joints, and as sealants to fill joints in pavements, and glass/metal connections. | may release sulfur; may contain PCBs; poor tensile strength; abrade easily; replaced in 1980s by silicone and urethane sealants |
| Butyl rubber | 1950s | Isobutylene-isoprene, Talc, Calcium carbonate, Mineral spirits, adhesion promoters | primarily used outdoors for metal and masonry joints that may expand and contract (gutters) | sticky and messy, but more resistant to sunlight than natural rubbers; combustible; paintable | |
| Acrylic (solvent-based) | 1958 | solvent cured acrylic resin with Calcium carbonate, Silica, Solvent and plasticizers. | |||
| Silicone | 1960s | Silicone resin cured with moisture or peroxides; may contain Fumed silica, Calcium carbonate, ground Quartz, Carbon black, Talc, plasticizers, Acetone, Methylene chloride. | Silastic, Clear Museum Gel | used around plumbing fixtures; to caulk joints in bathroom tiles; seal gap on exterior walls/roofs around pipes and wirings | water-repellent; long-life; wide temperature range; mold/mildew resistant; not paintable; poor adhesion; may release Acetic acid or Methanol on cure; may have residual curing compounds and silicone oils; may stain porous materials; some silicone caulks contain latex making them paintable but less durable |
| Polyurethane elastomers | Polyurethane cured with moisture, Calcium carbonate, Titanium dioxide, aromatic naphthas and petroleum distillates. | Vulkem | primarily used for sealing cracks and expansion joints in driveways and other outdoor concrete surfaces. It's also suitable for filling and repairing cracks in masonry-stucco walls. | very durable; abrasion resistant; flexible at low temperatures; combustible producing toxic fumes; may release acetic acid on curing, aging, or deterioration; susceptible to hydrolysis that may decrease adhesion | |
| Vinyl latex | late 1960s | Vinyl (Polyvinyl acetate) with calcium carbonate, plasticizers | Reprosil | fill small gaps and blemishes in wood trim prior to painting | inexpensive; may be painted and used outdoors; may evolve trace Acetic acid as it cures |
| Acrylic latex | Butyl methacrylate, Calcium carbonate, water | Flugger | fill small gaps and blemishes in wood trim prior to painting | inexpensive, fast-drying, and paintable; minimal shrinkage; used indoors |
Synonyms and Related Terms
caulking (noun); caulk (verb); calking; cauking (sp.); sealant; putty; spackle; Kitt (Deut.); Glaserkitt (Deut.); Fensterkitt (Deut.); kalfatring (Dan.)
Resources and Citations
- AIC Conservation Wiki: Caulk Sealants to Seal Exhibit Cases
- Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- ASTM, "Standard Terminology Relating to Paint, Varnish, Lacquer and Related Products", Annual Book of ASTM Standards, Section 6, Paints, Related Coatings and Aromatics, ASTM, D16, 7-Jan, Jul-96
- Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
- Ivan Myjer, contributed information, 1998
- Wikipedia: http://en.wikipedia.org/wiki/Caulking (Accessed Feb. 10, 2006)
- Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998