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Surface preparation THE WORK SITEIn general, the same recommendations that apply to the building of any craft using other materials or processes applies to building your boat with the GLEN-L Epoxy System. While often seen, do not build your boat in an open area exposed to direct sunlight. Build indoors or under cover whenever possible, protected from the direct sun as well as direct exposure to other elements. In all cases, some sort of cover over the work site is recommended to prevent dew or moisture from settling onto uncured activated POXY-SHIELD® resin-coated surfaces (uncured resin will tend to absorb moisture with a possibility of decreased bond strength). Also avoid working in high humidity whenever possible; drastic changes in humidity can affect bonding strength. If these conditions are probable, use POXY-GRIP® glue or POXY-SHIELD® Fast Hardener; avoid the use of the Slow Hardener. If working indoors or within a closed in area, make sure there is ample ventilation. If necessary, set up low velocity fans to assure a positive flow of air. High-speed fans will stir up dust and tend to evaporate any volatile solvents being used more rapidly. Ideal working temperatures range between 70oF and 85oF, although plus-or-minus about 5oF still allows good conditions for most aspects of the work. Use POXY-SHIELD® Fast Hardener exclusively when using the GLEN-L Epoxy Encapsulation System at temperatures below 65oF. The main problem at lower temperatures is protracted cure times, making building progress slower, and the increased chance of moisture exposure and surface contamination. TopSURFACE PREPARATIONWe have tested as many types of boatbuilding woods as we have been able to locate, and in all cases, we have had no bonding problems. Test sample bonds have always exceeded the strength of the wood. Thus, we feel that virtually any type of wood can be bonded with POXY-SHIELD® or POXY-GRIP® glue, as long as the mating surfaces have been properly prepared and instructions are followed. Cleanliness is the most important factor in bonding success. In all cases, joining surfaces must be clean and free of grease, oil, wax, dirt, or other contaminants. Do not apply to previously painted surfaces; apply only to bare wood, or to surfaces previously coated with epoxy (*). If coated surfaces are allowed to cure for more than approximately 24 to 48 hrs. (depending on temperature and hardener used) it is advisable to give the surface a solvent wipe and lightly sand. This is necessary whenever an "amine blush" or greasy film has appeared on the surface. (*) NOTE: Epoxy will stick with great tenacity to properly prepared fiberglass laminates or structures (such as existing boat hulls) made from polyester resin. However, one should not count only on the epoxy in this instance where the bonded component will be subjected to stress. The reason is that the epoxy will be so strong that a failure may occur in the actual fiberglass laminate itself (as opposed to the polyester/epoxy bond interface) resulting in damage to the laminate and/or get coat. Such junctions should be mechanically fastened as well whenever possible. Fiberglass surfaces should be prepared by thorough sanding to remove any gloss, paint, dirt, oil, or grease, and left with a roughened resin surface (take care NOT to cut into the actual fiberglass reinforcement). We have tested many woods all with excellent results, however, there is
still a chance that certain woods, in some circumstances, may present potential
bonding problems. Some woods are characteristically "difficult" to
glue, including white oak, teak, and sometimes even Douglas-fir (according to
some reports contrary to our testing). Although we have had no problems with
these woods ourselves, our conditions may be different from yours, and perhaps
test samples would be advisable. If such samples result in bond failure using
ordinary gluing procedures, then certain steps can be taken to assure sound
bonds, as follows (applicable to either POXY-GRIP® and POXY-SHIELD®, or
as noted): lf in doubt about adequate bonds, or your tests indicate a potential weakness on a wood not mentioned here, give the mating surfaces a solvent wipe first, such as with acetone or lacquer thinner; this is particularly effective with hard, dense hardwoods, or those with resinous or oily characteristics. TopSTORAGE & SHELF LIFEThe shelf life of properly stored POXY-SHIELD® resin and hardeners is a minimum of one year in unopened containers. POXY-GRIP® resin and hardener will have a storage life in excess of one year but may form some crystallization after a year. If this occurs, set the containers in warm water and the materials should return to their normal consistency. Products should not be stored at temperatures above 90oF with 60o to 80oF being the preferred range. Short term temperatures above or below these temperatures should not be harmful. Do not store in direct sunlight or near a heat source. Always keep containers sealed when not in use. Volatile constituents may evaporate and change the integrity of the products. Also, certain products may absorb moisture in high humidity conditions if left open. If products stand for a long period of time (6 months or longer), stir or agitate each ingredient before use. TopWOOD MOISTURE CONTENTAs a general rule, the drier wood is, the stronger it is. (Within certain limitations: wood that is over kiln dried can become brittle). This results from a strengthening of the cell walls as they as they dry out. The "problems" associated with wood are closely related to its moisture content. Wood will tend to seek a moisture equilibrium with the surrounding atmosphere. As moisture content increases or decreases, the wood swells or shrinks and changes in its strength characteristics and plays havoc on finishes. The potential problem that concerns wood workers when wood is used around "wet" environments is dry rot. Very dry wood or wood completely submerged in water is unlikely to suffer dry rot. This is because both moisture and oxygen are required for dry rot spores to thrive. The obvious solution to all of these moisture related problems is to make the wood impervious to moisture absorption/loss and reduce or eliminate the oxygen supply. For the mildest situations, paint or varnish may be enough to "stabilize" moisture content. But as years of experience has shown, in situations where wood is continually subjected to damp conditions, paint or varnish will fail as a barrier. To find a reasonable way to deal with the wood/moisture problems GLEN-L has developed the EPOXY Encapsulation System. Encapsulation not only makes possible the use of "non-marine" woods for boat construction but virtually eliminates dry rot and the problems resulting from changes in moisture content. The ideal moisture content of wood to be used in the Encapsulation System is 8 to 12%. At higher moisture contents, use POXY-GRIP® for gluing. Encapsulation is not recommended when the moisture content exceeds 18%, as internal stressing could affect the structural integrity. While in principle it is important to know these percentages, in practice it is difficult, if not impossible, for the home builder to determine moisture content of his lumber. However, with moisture content in mind take care how your lumber is stored and avoid encapsulation during a rainy spell or during or after any period of prolonged high humidity. Continue
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