Kaylo | Mesothelioma Claims

Kaylo was a rigid, white hydrous calcium silicate insulation in the form of molded pipe covering, block, and board. It was manufactured by the Owens-Illinois Glass Company beginning in 1943 and, from 1953, distributed nationally by the Owens-Corning Fiberglas Corporation, which bought the entire Kaylo business outright in 1958. It was one of the most widely installed high-temperature insulations of the mid-century, rated for piping and equipment surfaces up to 1200°F, and it was sold for decades with a phrase that appears on the sales literature in plain type: "non-toxic."

That word is the reason Kaylo occupies a distinct place in asbestos litigation. Most asbestos product cases turn on failure to warn, which occurs when the manufacturer stayed silent about a hazard it should have investigated. The Kaylo record is different because the manufacturer didn't just fail to warn, they actually lied about the safety of their product.

The manufacturer's own commissioned science told it three things, in writing, before and during the product's commercial life: that Kaylo dust caused asbestosis (1948), that the asbestos could be removed entirely and replaced with wood pulp at equal strength (1946), and that asbestos was "fairly well incriminated as a carcinogen" (1956). The company marketed the product as "non-toxic" anyway. The Kaylo documents are, for that reason, among the most frequently cited document in the entire asbestos story.

What Kaylo was

Kaylo was a hydrous calcium silicate insulation: a suspension of lime (calcium hydroxide), silica, and asbestos, reacted under steam pressure in an autoclave to form a rigid, lightweight, microporous solid. Owens-Illinois developed it at its research operation and had it at pilot-plant stage by 1943; commercial production ran principally out of the Berlin, New Jersey and Sayreville, New Jersey plants. The finished product analyzed at roughly 80% hydrous calcium silicate, under 15% chrysotile, and about 1% quartz in its early formulation. The calcium silicate matrix provided the insulating value and the asbestos providing mechanical reinforcement.

The asbestos content and mineralogy changed over the product's life, which matters for exposure attribution:

• Early formulation (1943–~1955): chrysotile only, on the order of 5–20% by weight depending on grade and sampling.
• Later formulation (~1955 onward): an amosite-plus-chrysotile blend. By the 1959 OCF manufacturing manual, Kaylo-10 insulation ran about 16.4% asbestos by dry weight (a mix of AW and W-3 amosite and 6D and 4K chrysotile), and the heavier Kaylo-20 thermal grade ran near 20%, majority amosite.

Learn more about chrysotile and amosite.

Kaylo was made in two broad grades: a light grade for thermal pipe and equipment insulation, and a heavy grade used for fire bucks and fire doors. The raw chrysotile fiber came from Johns-Manville and North American Asbestos Corporation supplied the amosite. Another type of asbestos known as crocidolite was noted as performing well but was priced out of the formulation.

Why amosite Kaylo turned pink

The shift from chrysotile to an amosite blend around 1955 left a visible signature that is useful for product identification, and the reason for it is chemical. The 1959 Taylor manufacturing manual explains that amosite was preferred partly because it produced lower k-factors (insulation value) at higher mean temperatures. In fact, that's where the name Kaylo came from: The product's "k-factor" is low. The manual attributes this to amosite being an iron compound: iron is effective at blocking infrared (radiant) heat transfer, which becomes the dominant mode of heat flow at high temperatures, so an iron-bearing fiber suppresses the radiant component that a non-iron fiber like chrysotile does not.

The color change is the outward evidence of what the iron does inside the material. During and after autoclaving, and especially after the product is heated in service, some of that ferrous iron in amosite undergoes a base-exchange reaction with the lime (calcium oxide) of the batch and disseminates out of the fiber and throughout the surrounding hydrous calcium silicate matrix. Iron compounds are intensely colored; once iron is distributed through the formerly white calcium silicate body, the whole product takes on a uniform pink cast after high-temperature exposure. Chrysotile has no appreciable iron, so chrysotile-only Kaylo stayed white. In practical terms: a white calcium silicate insulation is consistent with the earlier chrysotile formulation; a pink one that has seen service heat signals the amosite blend, and therefore the higher-potency amphibole fiber.

The Taylor manual flags a consequence of this reaction that its author found genuinely unresolved. Kaylo's insulating performance depends on getting the right ratio so that the lime and silica combine to form the intended hydrous calcium silicate. If a meaningful share of the batch lime is instead being consumed by base exchange with amosite iron, that lime is diverted away from the silicate-forming reaction, and the actual ratio may differ from the one the formula was designed around. Taylor noted that the amounts of iron and lime involved were unknown and that the phenomenon "would be most worthwhile" to study. That's a candid acknowledgment, in the manufacturer's own internal manual, that the switch to amosite altered the product's fundamental chemistry in a way the company had not fully characterized.

Product origins and the two-company chain

Owens-Illinois Glass Company developed, tested, and manufactured Kaylo from 1943. It was O-I that commissioned the Saranac Laboratory animal studies, received the Arthur D. Little development reports, and ran the plants at Berlin and Sayreville through the early-to-mid 1950s.

Owens-Corning Fiberglas Corporation was a joint venture originally formed by Owens-Illinois and Corning Glass Works. It became the national distributor of Kaylo in 1953 and purchased the Kaylo business from Owens-Illinois in 1958, thereafter manufacturing and selling it under the Owens-Corning name until Kaylo was discontinued in the early 1970s.

Because both companies now fund asbestos trusts, the exposure period maps cleanly onto recovery: the Paddock Enterprises trust (Owens-Illinois's reorganized entity, which filed for Chapter 11 in 2020) pays for pre-1959 Kaylo exposure, and the Owens Corning/Fibreboard Asbestos Personal Injury Trust (established following Owens-Corning's 2000 Chapter 11 filing) pays for 1959-forward exposure. .

The marketing: "non-toxic," to 1200°F

By the mid-1950s Kaylo pipe insulation was sold under the Owens-Corning Fiberglas name as a premium high-temperature calcium silicate. The October 1956 sales sheet is representative and is frequently entered as an exhibit.

The brochure describes Kaylo as "a white, rigid hydrous calcium silicate heat insulation, manufactured by Owens-Illinois Glass Company and distributed nationally by Owens-Corning Fiberglas Corporation," effective for indoor and outdoor piping up to 1200°F. It concedes the asbestos content in a single soft phrase: "A chemically reacted material, Kaylo Pipe Insulation contains no added binder. For mechanical effects, a small amount of asbestos fiber is included at the time of manufacture."

The claim that matters is in the "easy fabrication" selling point. Ordinary tools of the trade, the brochure says, are "sufficient for all cutting, sawing or scoring," and the material is "Non-irritating to the skin and non-toxic," and "offers pleasant handling characteristics."

Three things about that sentence. First, it is an affirmative representation of safety. That's what separates a failure-to-warn claim from a fraudulent-misrepresentation claim, and the reason punitive damages were frequently awarded in Kaylo lawsuits. Second, the representation is attached precisely to the cutting and sawing operations that liberate respirable fiber. The brochure reassures the tradesman about the dust at the exact moment he is about to generate it. Third, "non-toxic" was not a one-time copy error: the phrase recurs across multiple Kaylo brochures over a span of years. The word survived every revision cycle in which someone could have removed it.

The brochure was in national distribution in 1956. Owens-Illinois's own commissioned researcher had put the opposite conclusion in writing eight years earlier.

What the manufacturer knew, in writing

The Kaylo state-of-the-art record is a dated sequence of documents in the manufacturers' own files. This chronology gives the broad overview of what Owens-Illinois and Owens-Corning knew and when.

1942 — Owens-Corning assembles a "weapon-in-reserve"

Before Kaylo existed as a commercial product, Owens-Corning Fiberglas already understood that asbestos disease was richly documented in the medical literature. A January 7, 1942 intra-company memorandum (to E.J. Marshall, copied to OCF president Harold Boeschenstein) reviewing the company's posture toward the Asbestos Workers Union proposed, as "Strategy for 1942," that the company "take the offensive." Its first suggested step: "Gather as a weapon-in-reserve an impressive file of photostats of medical literature on asbestosis." The available bibliographies, the memo noted, covered the medical literature to 1938 and cited "scores of publications in which the lung and skin hazards of asbestos are discussed," which was a file of "five or six hundred pages."

The memo's proposed use of that knowledge is what makes it so utterly damning. The plan was to offer Asbestos Workers Union members a group insurance arrangement through Aetna covering their handling of Fiberglas products — and, if the union's leadership reacted unfavorably, to "use the asbestosis weapon-in-reserve to let them stew." The lever: an implied threat to distribute U.S. Public Health Bulletin #241 on asbestosis to the union membership, a step the memo calculated "may provide an opportunity to promote dissension in the ranks that conceivably could bring about over-throw of the present Union leadership."

That threat only works as a threat under one assumption: that the rank-and-file asbestos workers did not already know what Bulletin #241 contained,. which was a warning about the risks of asbestosis. The 1942 memo is therefore not merely evidence that Owens-Corning knew asbestos caused asbestosis — it is evidence that Owens-Corning knew the workers handling asbestos did not know, and viewed their ignorance as a commercial asset: disclosure was something to be dangled and withheld to win sales and split a union, not something owed to the men breathing the dust. The company held this understanding of both the hazard and the workforce's ignorance of it in 1942 — more than a decade before it began distributing Kaylo in 1953, and sixteen years before it bought the product line in 1958. When Owens-Corning later printed "non-toxic" on Kaylo sales literature aimed at those same trades, it did so as a company that had already documented, in its own files, both the hazard and the fact that its customers were unaware of it.

1946 — Arthur D. Little proves the asbestos can be removed

In March 1946, the Arthur D. Little consulting laboratory delivered to Owens-Illinois its Eighth Progress Report on the Fundamental Study of Microporite (the internal name for the Kaylo material). The report's central finding was that kraft paper pulp could replace the asbestos in Kaylo entirely, at equal strength and with less fiber required. In ADL's words, "kraft fibers are equal to asbestos fibers for the strengthening or reinforcing of K-LO." Over 200 experimental batches supported the conclusion; four autoclave series established that all-kraft batches performed about as well as the asbestos formulations. ADL's first recommendation was that the plant try kraft in place of asbestos.

The date is what makes this document extraordinary. In 1946, Owens-Illinois had in hand a demonstrated, tested, equal-strength substitute that would have eliminated the asbestos hazard from Kaylo entirely. The Saranac animal studies were then underway; the disease findings were two years off. The company therefore learned that asbestos could be removed before it learned, definitively, that the asbestos needed to be removed. It kept the asbestos in the product for roughly a quarter-century anyway.

1948 — Saranac confirms Kaylo causes asbestosis

Owens-Illinois had commissioned the Saranac Laboratory (at the time the country's foremost occupational-disease research institution) to determine, before Kaylo went to large-scale commercial use, "whether or not any dust liberated from this product during manufacture, handling, or fabrication would be likely to constitute a respiratory hazard to exposed individuals." Dust for the studies was taken from the dust collectors of the Berlin, New Jersey plant. The tests began in 1945.

On November 16, 1948, Dr. Arthur Vorwald of Saranac wrote to O-I's U.E. Bowes transmitting the interim report. His letter states that in animals sacrificed after more than thirty months of exposure to Kaylo dust, "unmistakable evidence of asbestosis has developed showing that Kaylo on inhalation is capable of producing asbestosis and must be regarded as a potentially hazardous material."

The letter's next passage is the one most often quoted, because it frames the disease finding entirely in terms of the company's advantage:

"Since Kaylo is capable of producing asbestosis, it is better to discover it now in animals rather than later in industrial workers. Thus, the company, being forewarned, will be in a better position to institute adequate control measures for safeguarding exposed employees and protecting its own interests."

The accompanying interim report (Vorwald, Pratt, Durkan, and Delahant, October 30, 1948) concluded that Kaylo "is capable, on prolonged inhalation, of producing asbestosis in the lungs of guinea pigs, and that it should be handled industrially as a hazardous dust." It explained that "the asbestos in Kaylo is unaltered during manufacture" and that it "maintains its capacity to cause fibrosis." A companion request in the correspondence asked that the asbestosis discussion not be disseminated.

1952 — the final report

The final Saranac Kaylo report (January 30, 1952) confirmed the finding across the full study: "Kaylo dust when inhaled by pigs for a prolonged period (30–36 months) is capable of producing the peribronchiolar fibrosis characteristic of asbestosis." Its formal conclusion: "Kaylo because of its content of an appreciable amount of fibrous chrysotile is capable of producing asbestosis and should be handled as a hazardous industrial dust."

1954–1956 — the independent review, and asbestos as a carcinogen

In 1954 O-I engaged Dr. G.W.H. Schepers to review Vorwald's Kaylo materials independently. Schepers later testified that he performed his review without the benefit of Vorwald's 1952 report, and his evaluation found more disease, appearing earlier, across all the animals — including rats that Vorwald's account had treated as unaffected. Schepers published on the Kaylo experiments in 1955.

By 1956, Schepers (who was )then directing Saranac's fiberglass studies for Owens-Corning) put the carcinogen problem in writing to OCF. In a February 6, 1956 letter to OCF's director of personnel and industrial relations (concerning the company's fiberglass toxicity program), Schepers observed that "asbestos is fairly well incriminated as a carcinogen and the asbestos causes lung damage by virtue of the length of its fibers." The same letter, notably, offered to help OCF explain the research to "lay personnel" and cautioned that the company might "have difficulty with published statements too." That 1956 letter concerns fiberglass, not Kaylo directly; its relevance is that it places asbestos-carcinogen knowledge in Owens-Corning's hands, in writing, in the same year the "non-toxic" Kaylo brochure was in national circulation.

The exposure the documents describe

The Kaylo file is unusual in that the manufacturers' own industrial-hygiene surveys quantify the exposures the marketing minimized.

O-I's own industrial hygiene survey of the Sayreville plant (May 29, 1951) sampled seven locations, found chrysotile constituting 5–20% of the dust, and recorded that where asbestos was in the air, the TLV was exceeded in four operations. Conditions inside boxcars loading the product approached 50 mppcf by estimate; the survey recommended dust education, clothing changes, respirators in the boxcars, monthly dust counts, and x-rays. It also cautioned that meeting the TLV was no guarantee that disease would not appear.

The fabrication exposures were higher still, and they fell on the end users the "non-toxic" brochure addressed. A Saranac-associated dust experiment in a saw room (recorded in an occupational-disease case file, July 1956) measured a work room at 4.2 mppcf, ten feet from the saw at 8.2 mppcf, and at the power saw itself 21 mppcf — against the 5 mppcf standard of the day — with 98% of the particles under 10 microns, i.e. in the respirable range. Cutting and sawing Kaylo, the operation the brochure called "non-irritating... non-toxic," generated respirable asbestos dust at multiples of the permissible limit.

mppcf stands for million particles per cubic foot of air — the unit U.S. industrial hygiene relied on to measure airborne dust from the 1930s into the early 1970s. The measure was displaced in 1971, when OSHA adopted fibers per cubic centimeter (f/cc), counted by phase-contrast microscopy. Converting these old particle counts into the fiber measure used today isn't a simple multiplication — the two methods count different things. See Understanding Asbestos Exposure for more on dust counts.

The exposed population was correspondingly broad: insulators and pipecoverers who cut and fitted Kaylo pipe covering and block; shipyard workers who insulated piping and equipment in ships' holds; construction trades working around insulation application; the manufacturers' own plant and boxcar workers; and the maintenance, renovation, and demolition trades who disturb installed Kaylo to this day. Kaylo pipe insulation installed from the 1940s through the early 1970s remains in older industrial facilities, power plants, and vessels, and its disturbance remains a live exposure pathway.

Source documents

The factual material on this page is drawn from the following primary sources:

• Owens-Corning Fiberglas Corporation, Kaylo Pipe Insulation sales brochure IN1.C5, October 1956 (trial Exhibit B) — source of the "non-irritating to the skin and non-toxic" fabrication claim and the 1200°F rating.
• Arthur D. Little, Inc., "Eighth Progress Report on the Fundamental Study of Microporite," March 27, 1946 (C-57334, to W.E. Bowes, Owens-Illinois, Toledo) — the kraft-pulp substitution study concluding asbestos could be eliminated at equal strength.
• Owens-Illinois / Saranac Laboratory correspondence and reports, 1948–1956 — including the Vorwald-to-Bowes letter of November 16, 1948; the Vorwald, Pratt, Durkan & Delahant interim report of October 30, 1948; the final Kaylo report of January 30, 1952; the O-I Sayreville industrial hygiene survey of May 29, 1951; and the Schepers independent review materials (1954–55).
• G.W.H. Schepers (Saranac Laboratory) to M.D. Burch (Owens-Corning Fiberglas), February 6, 1956 (Bates 01 501 1308–1311) — fiberglass toxicity correspondence placing asbestos-carcinogen knowledge in OCF's hands.
• Owens-Corning Fiberglas Corporation intra-company memorandum, "Asbestos Workers Union," January 7, 1942 (Bates 01 022 0350–0351) — the "weapon-in-reserve" asbestos-literature strategy.
• W.C. Taylor, "The Manufacture of Kaylo Products," Owens-Corning Fiberglas, June 10, 1959 (Bates 01 062 series) — the formulation and fiber-supplier record.

The documentary chronology summarized here is treated comprehensively in Barry I. Castleman, Asbestos: Medical and Legal Aspects (the standard reference work on asbestos state-of-the-art), to which the reader is referred for the full underlying correspondence and its litigation history.