Fiberglass pool making process involves different resin and reinforcement materials available when working with composites. There are three main resins used for most composite structures, as well as the most common reinforcements.
Fiberglass pool materials
A composite structure consists of a thermosetting resin used in conjunction with some type of reinforcement, such as woven fiberglass cloth. The three main types of room-temperature-curing resins used in composite fabrication are polyester, vinyl ester and epoxy resins.
Polyester resin Polyester resin
is a general-purpose resin suitable for a wide variety of applications. Methyl Ethyl Ketone Peroxide
) must be used as the catalyst to begin the curing process. Catalyzation
rates can be varied with polyester resins
in order to adjust for various environmental conditions. In thin laminations
or when gel coat
is sprayed as a topcoat, the surface may remain tacky and not cure properly if left exposed to the air. To get a complete cure, thin laminations
or top coats must contain either styrene wax
solution of have a coat of polyvinyl alcohol
) solution sprayed over them to seal out the air. With the former, the wax "floats" to the surface as the resin cures, acting as a barrier to the air. Styrene wax
must be sanded off after curing, but PVA
can be rinsed off with warm water.
Epoxy resins Epoxy resins
are not as forgiving in their measurement as polyester resins
, but epoxies provide a greater part strength and dimensional stability. They also adhere to other materials better than polyester resins
. Epoxy hardener ratios can't be varied, and adequate temperatures (at least 70 degrees F) must be maintained during the curing process. Epoxy resin
systems tend to cost more than polyester resins
, but they are a virtual necessity in some repair applications, such as with Sheet Molded Compound
). Epoxy resins
are also highly recommended for use with Kevlar
® and carbon fiber
Vinyl ester resinVinyl ester resin
, possesses qualities that fall between polyester resins
and epoxy resins
for the most part. It excels above both, however, in the areas of corrosion resistance, temperature resistance (it's good to 300 degrees F), and toughness. Common uses include boat hull repair, full tank construction and chemical storage tank linings. Like polyester resin
, it is catalyzed with MEKP, but vinyl ester
has a shorter three-month shelf life.
There are many reinforcing fabrics available that are used with the resins discussed. The three types of reinforcing fabrics most commonly used are fiberglass, Kevlar
® (Aramaids) and carbon fiber (graphite). Each possesses different qualities and advantages. All three are usually available as tows or rovings, veil mats and woven fabrics. Additionally, fiberglass is available as a chopped strand mat, which consists of short, randomly oriented fibers held together by a binder.
Carbon fiber costs the most to purchase, but it offers exceptionally high strength and stiffness while being extremely lightweight. Kevlar® is also lightweight and offers excellent abrasion resistance. It is, however, difficult to cut and wet out with resin. For finishing purposes, fabricators often use a surface layer of lightweight fiberglass cloth in Kevlar® laminates, because Kevlar® is virtually impossible to sand once cured. Most general-purpose applications utilize fiberglass cloth. Although it lacks the lightweight and high strength of carbon fiber or Kevlar®, it is considerably cheaper to purchase. Fiberglass cloth comes in a wide variety of styles and weights, making it ideal for many applications. High-strength weave styles are available, and these could be considered cost effective alternatives to the more advanced fabrics.
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