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Wood Repair Bibliography

Phillips, Morgan W. and Dr. Judith E. Selwyn.Epoxies for Wood Repairs in Historic Buildings. Washington, DC: Office of Archeology and Historic Preservation, Heritage Conservation and Recreation ServiceU.S. Department of the Interior, 1978

This publication deals with two main subjects; 1) the chemical compositions and uses for epoxies in wood consolidants and patching; and 2) case studies involving the restoration of the Longfellow house. Although published in 1978, much of the information contained in it is relevant today. Much of what is discussed is highly technical. In addition, more recent information merely expounds on this information.

Kahn, Eve M. "Wood Restoration: Epoxies Fill in the G * A * P * S," Clem Labine’s Traditional Building, Sept – Oct 1991, v. 4, no. 5: pg. 16-23.

Of all the topics in restoration the one that is most misunderstood deals with epoxy work. In selecting epoxy to work with, one must follow certain guidelines:

  1. Epoxy is the right job when one wants to keep: *the historical material and minimizing disruption to intact elements are important; * the parts in need of restoration would be difficult to replace; * nearly invisible repairs are desired; and * skilled craftspeople are available (Kahn, p. 16)
  2. Choose an epoxy suited to the project.
  3. Be wary of inexpensive formulas.
  4. Make sure the epoxy’s cure time fits your needs.
  5. Epoxies that mix 1:1 are easiest to handle in the field.
  6. Don’t forget the effect of climate on epoxy. Heat speeds cure time, so mix small batches when working in strong sunlight.
  7. Don’t slather sound wood with epoxy in an effort to protect it. Wood under consolidated areas can rot because of trapped moisture.
  8. Be aware of the controversy surrounding the use of solvents in epoxy. There are many products now available without solvents.
  9. Use pigments only as the manufacturers recommend.

Marshall, James R. "A Specifier's Guide to Epoxies for Restoration & Repair," Clem Labine’s Traditional Building, Jan-Feb 1998, v. 11, no. 1: pg. 20, 22, 24

This article by James R. Marshall discusses the uses of epoxies for restoration and repair. Developed late in World War II, epoxies first were developed as super strong adhesives. They have evolved into one of the most versatile materials now available for all manners of restoration and repair (Marshall, p. 20). Not only are epoxies today used as adhesives, but for structural component restoration as well. Wood restoration problems include rotted, dried out or spongy wood. For wood restoration, the process is normally a two step process involving a consolidant (the primer) and a hardener.

There are varying beliefs involving the success or failure of the consolidation approach. Mr. John Stahl, the technical director of Advanced Repair Technology, believes that the pre-consolidation approach will lead to eventual failure. His belief is in a system that involves a primatrate (a two-part low viscosity epoxy and an elastomeric wood repair compound). By using paint brushes to apply the primatrate, it penetrates the wood fibers, which is essential in making the wood stronger. Mr. Stahl also maintains that all decayed wood be removed prior to beginning the restoration process. By not removing the decayed wood, problems such as expansion/contraction in the decayed wood compromises the bond, inadequate “peel strength” in the epoxies, and inadequate flexural strength in the epoxies all can lead to failure. (Marshall, p. 20)

Mr. Marshall also expounds the virtue of epoxies in the restoration of structural components, such as support timbers. Epoxies work well in compressive situations because epoxy compounds can be stronger than concrete in compression. As for tension, the answer is also yes. However, when using epoxy in elements in tension, such as a beam, it is essential that a structural engineer signs off on the work. The lack of proper engineering for a structural repair can result in tremendous failure. For example, if a wooden beam’s end is decayed in a masonry pocket, the epoxy used in the repair must be treated like concrete and aggregate added to it. In addition, the restored section must be firmly tied into the sound portion of the beam by the use of fiberglass (not metal) rods. Fiberglass rods work better than metal rods for two reasons: 1) fiberglass and epoxies have similar expansion/contraction characteristics; and 2) residual oils on metal could disturb the epoxy bond.

Lief, Judith Siegel. "The Wide World of Epoxies," Clem Labine’s Traditional Building, Sept – Oct 1995, v. 8, no. 5: pg. 34, 36

According to Judith Siegel Lief, the domains of epoxy liquids run the gamut between adhesives (known as the Cadillac of glues because they are virtually shrink free and bond to almost all materials) to wood consolidants and fillers (including bonding agents, marine resins, crack injection compounds, concrete restoration products and structural adhesives).

Prior to using epoxies, one needs to know what the problem is and what is available to fix it. Epoxies are classified into three main categories:

  1. Wood Consolidents: The use of low viscosity epoxy that is clear in appearance and which stabilizes and strengthens the remaining wood. Three primary factors affect the rate of curing: a) temperature of the epoxy; b) amount of material being treated; and c) environmental temperature.
  2. Cosmetic/Non-Structural Repair
  3. Structural Repairs: Epoxies can be formulated with good flow characteristics so, mixed with aggregates, they can be used like concrete. Included would be fiberglass rods (65% glass + 35% polyester fill) which would make the repair load bearing and structurally reliable.

Leeke, John. "How to Use Epoxies to Repair Rotted Exterior Wood," Old House Journal, May – June 1989, v. 17, no. 3; pg. 22 - 24

John Leeke concentrates primarily on the repair and restoration of non- structural wood. Some of the advantages in using epoxies include ease of learning to use epoxy; epoxy materials hold up well to weather; it may not be necessary to remove affected parts from the building; and epoxy repair saves as much of the original material as possible. Epoxy should only be considered where long life is the goal of the project. Mr. Leeke recommends keeping a epoxy kit on hand for quick repair work. Within this kit should be:

  • two 10 fluid oz. cans with snap on lids; each labeled with parts A and B of the adhesive paste filler
  • two 8 fluid oz bottles, each labeled with parts A and B of the consolidant
  • a few empty bottles for mixing and application
  • rags of various sizes
  • gloves; several disposable and one heavy pair
  • oil clay
  • putty knives
  • mixing boards
  • epoxy materials
  • 2 dozen application bottles
  • mixing sticks
  • bottle cleaning tools
  • channel lock pliers
  • allen wrenches
  • needlenose pliers

Use clean mixing materials and tools to avoid contamination and maximum penetration is required for an effective bond.

Practice safety when using epoxies:

  • epoxies are toxic chemicals
  • avoid contact with eyes and skin
  • avoid breathing fumes
  • watch for spills and drips
  • use soap and/or detergents not solvents to wash off of skin
  • use disposable stir sticks and gloves
  • epoxies are flammable

 

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