Resin mixing is an important part of composite manufacturing. Here's how to do it safely and with an acceptable margin of accuracy.
WARNING - THESE INSTRUCTIONS INVOLVE THE USE OF METHYL ETHYL KEYTONE PEROXIDE (MEK-P), A CORROSIVE COMPOUND THAT IS MILDLY "EXPLOSIVE." GLOVES ARE A MUST AROUND THESE COMPOUNDS AS THEY WILL ATTACK ORGANIC LIFE FORMS - THAT MEANS YOU, YOU MEAT PERSON!
IF YOUR SKIN IS SPLASHED, IMMEDIATELY WASH WITH SOAP AND WATER - DO NO DILUTE WITH ACETONE. SEEK MEDICAL ATTENTION IF YOU HAVE A SEVERE REACTION OR DEVELOP A FEVER.
FIRE ADVISORY - POLYESTER RESIN IS FLAMMABLE. DO NOT SMOKE OR HAVE AN OPEN FLAME NEAR YOUR WORKING OR STORAGE AREA. DO NOT LEAVE CATALYZED RESIN UNATTENDED WHEN IN SIGNIFICANT QUANTITIES AS THERE IS A POSSIBILITY OF SPONTANEOUS COMBUSTION. SHOULD YOU HAVE A FIRE EMERGENCY, SMOTHER THE FLAME.
The following video is long, but full of tips, tricks and advice for working with resin for layup.
Glossary MEKP - Methyl Ethyl Keytone Peroxide - polyester resin catalyst (hardener) PVA - Polyvinyl Alcohol (film mold release) Cabosil - the white silica filler being mixed in (trade name - aka Aerosil) Tool - negative mold used to make parts Micro Balloons - air filler encapsulated in silica glass (creates a lattice matrix structure in resin) Gelcoat - provides a high quality finish to composite tool surface Composite - material made from two or more substances (in this case fiber glass and resin) Mat - Reference to chopped fiberglass in a sheet form; tearable by hand with strands about 1.5" long Exotherm - reference to the heat generated/required by the resin to cure Pot - Catalyzed batch of resin Pot Life - Working/usable life of pot. After this time, the chemical reactions between catalyst and resin "take off"
Polyester resin is a synthetic resin (that is, it starts off as a fluid and hardens). Polyester resin is one of the more common forms of resins - epoxy resin being another very common form. When it comes to the marine industry, polyester resin is the most common as it is more rigid than it's epoxy counterpart. Keep in mind, the trade off for it's higher stiffness is that it is more brittle.
In its viscous form, polyester resin is flammable and a skin irritant - something we expect from a styrene based fluid. Manufactures mix their own blend of cobalt and other conditioner additives to help the curing process - however, Methyl Ethyl Keytone Peroxide is used as a catalyst.
Polyester resin is very common in tooling - that is, making molds (typically negative molds) that will be used to make a product. A major reason for this is, again, it's rigidity.
Finally, polyester resins are compatible with any type of fiberglass, fibrous carbon, Kevlar and urethane type foams (NOT styrene type foams). While the resin itself is compatible, the catalyst may not be (especially with foams). A test sample is always recommended before tooling.