A few words on fiberglass

 

As I will be doing a lot of fiberglass work on these pages I should take a few minutes to talk fiberglass, resin choices and safety. 

First a few words on safety and comfort.  Most folks find fiberglass itchy and irritating on their skin.  I wear long sleeves, a head cover and gloves in addition to safety goggles and a filtering mask when sanding, grinding or cutting fiberglass.  If that powdery residue flying off your grinding wheel is that irritating to your skin imagine what it can do to your eyes and lungs!!  Be safe folks.  My desire here is not to fill you in on every detail of fiberglass safety, just to tell you to do your reading before you do yourself permanent harm!   Oh and by the way when I work with the resin the mask is switched from a particulate to a vapor filtering mask, I can’t afford to lose any of my few remaining brain cells.

Fiberglass, most of the work done here will be with various weights of mat, which is made from randomly oriented pieces of glass fiber held together in a sheet by a temporary binding agent.  I like to use lighter weights of mat in the layers closest to the gelcoat surface to reduce the chances of print through on the final product.  The weight of mat used is gradually increased in layers farther from the finished surface.  I start with ¾ oz glass for 2 layers and then continue adding 1 ½ oz layers until I have built the desired thickness on repairs.   For production of the mold and the bodies I will start with ¾ oz, then 1 ½ oz, then 2 oz, then another layer of 2oz for productions bodies and even more for some areas of the mold.

Others have their views on how to do fiberglass repairs and that’s fine.  If you follow a few basic rules fiberglass is a fairly forgiving material.  I never use cloth except as a thickening or strengthening layer well away from the finished surface.  I am not a fiberglass expert but have had excellent results repairing a crashed fiberglass buggy, repairing both the crash damage which was extensive, and the multitude of holes various owners had drilled for tops, lights, gas filler openings and a few holes whose purpose I was never able to determine.  The body was still in primer, but ready for paint when a guy came along that wanted it more than I did.  By that I mean he found the price point where my not wanting to sell fell victim to my family needing the cash. L   Keep the glass matt and or cloth you use clean, work on a clean grease free surface and store it wrapped in plastic when not in use.

Resin, oh boy here is where I step on a few toes.  You can buy cheap resin at any number of places but you need to be aware of a few things.  First resin has a shelf life of about three months if kept cool and then begins to deteriorate.  The Methyl Ethyl Keytone Peroxide or MEKP hardener should be kept cool until use as well.   The big box store may have the stuff on the shelf for a year or more with the tube of hardener fastened to the top of the can.  For a few $ more you can order your supplies from a reputable supplier, have them shipped to your home, and have the benefit of fresh materials.  These bulk suppliers also have expert advice that may help you save a lot of time and aggravation in your project.  My latest order was from US Composites out of Florida.  They answered all my questions and ship fresh product in a timely manner and no I don’t get a discount for mentioning them but maybe if enough of you tell them Gray Goats Garage I sent you I might! 

Finally a word about resin types, the cheap “marine grade” stuff is in my mind to be avoided for work on cars.  Ever heard the rumors about not being able to paint a fiberglass car black or it will warp in the sun?  Stories like that start with choices regarding which resin you use. 

The problem is the Temperature Distortion Point or TDP, the point at which the resin softens and can warp.  Inexpensive and general purpose resins soften at as little as 140- 160 degrees and a dark colored car in the sun has no trouble reaching that temperature range.  Most suppliers recommend that car fiberglass use a resin with a TDP n the 180-190 degree range.  I prefer ISO or Isophalic resin with a TDP of around 240 degrees.  That way no matter what color the car is eventually painted it will remain stable and not develop waves or print through.  Now ISO resins cost a little more but if you care about the quality and longevity of your project it is worth the few extra dollars spent.  It’s really not much more for the good stuff.  And that’s saying something coming from a tight wad like me! 

What about epoxy resins?  They are great for their designated purposes but are more expensive, more sensitive to mix ratio, harder to work with and more difficult to repair if your project should ever be damaged.  Just not worth it to me for this kind of work.

Remember the good stuff aint cheap but quality rarely is and C Buckets will only be made of high quality glass and Isophalic resin