Sunday, July 29, 2012

Fiberglass "Structural Peanut Butter" Recipe

As you have read through my posts you have heard me make mention of Fiberglass Structural Peanut Butter. Well here is the recipe:

This stuff is great for filling in crevices where panels join together leaving small voids, just fill in the void areas with this mixture prior to installing fiberglass cloth tape.  Also, great for filling in a hole, various types of repairs, creating reinforced areas for bolt throughs, and so on.  Not only does this mixture fill in voids but it is actually structural in its composition when cured.  Thus, leaving you with a very strong, high load, high tensile strength region when cured.

You will need the following materials which are readily available at fiberglass supply stores online.  I purchase all of my stuff from USComposites in West Palm Beach, Florida because of their high quality resins and cloth, quick shipping, great packaging of items shipped and you can speak with a Fiberglass Technical Representative anytime by simply making a phone call.  Very knowledgeable tech reps by the way.

This is all you need to make the mixture:
  1. Aerosil - resin thickening agent
  2. Glass Bubbles
  3. Glass Reinforcer material:  (choose only one of these)
    • 1/32" Milled Fibers for very small cracks and voids
    • 1/4" Fiberglass strands for cracks 1/4" wide and wider
    • 1/2" Fiberglass strands for cracks 1/2" wide and wider or for filling large areas where greater strength is needed such as reinforcements for bolt throughs and for larger voids
  4. Polyester Resin
  5. Catalyst
  6. A couple of hard plastic (2 cup) measuring cups for mixing mixture in.  The type that are sold at most Dollar Stores work really well.
As far as the mixture reinforcers are concerned, simply choose one dependent upon type of repair at hand.  
showing three parts used to make runnier type mixture for small voids

showing three parts used to make mixture for 1/4" cracks and larger
Glass Reinforcer Agent Choices (the pictures below are close up views of #3 ingredients above)
These agents really give the mixture its strength, without which the polyester resin would simply become too brittle and would crack.  These agents not only bind mixture together through a chemical matrix but provide structural strength that yields high tensile strengths. 

  • 1/32" Milled Fibers for very small cracks and voids
  • 1/4" Fiberglass strands for cracks 1/4" wide and wider
  • 1/2" Fiberglass strands for cracks 1/2" wide and wider or for filling large areas where greater strength is needed such as reinforcements for bolt throughs and for larger voids




To make the mixture I would suggest starting out with 4 ounces of resin.  This amount works good for providing you with ample amounts of work time so you do not have to worry about your resin pot life.  You can take your time and work the repair properly by filling in with this compound, not having to worry about your mixture curing out while you are in the middle of a job.  So this is a good amount to start with.
  1. Pour 4 ounces of polyester resin into measuring cup
  2. Add appropriate catalyst 
  3. Stir thoroughly 
  4. then add your Aerosil, glass bubbles and choice of glass reinforcement material using the small medicinal cup that is provided with materials at purchase
Stir all the agents thoroughly with small tongue depressor until it is obvious that all elements have become homogenous with the mixture. 

You can tweak the mixture by adding more fiberglass fibers, fiberglass strands or if you need a little thicker mixture - add some more aerosil to the mixture.  Aersosil (Cabosil) will change the consistency of the mixture making it thicker.  It takes quite a bit to change the consistency of mixture so when ordering Aerosil, order twice as much as the other ingredients.  

You can make it to any consistency that your repair needs. - Need to inject the mixture within a tight crevice with the use of syringe just mix loosely, need to repair larger void mix more Aersosil and make to consistency of peanut butter.  Hence, Fiberglass Structural Peanut Butter.

 
 
 

Now this mixture is a little loose for it is composed of the 1/32" Milled Fibers.  I wanted this mixture to be a little loose because I am using it for filleting inside corners and need the capillary action of the mixture to be drawn into some 1/16"-1/8" cracks.

However, if you were to add the 1/4" or 1/2" fiberglass strands to the mixture along with more aerosil (cabosil)  it would indeed begin to be comparable to Peanut Butter in consistency, whereas this particular mix is not necessarily so.



By the way, wear a good respirator for filtering out fine particulates, you certainly do not need to be breathing in 'glass spheres' or milled fibers.  I like to wear a combination particulate matter filter/organic vapor filter in my respirator. Has both filters made into one cartridge, breathing in the styrene vapors from polyester resin is extremely hazardous to our central nervous system.

Chris

No comments:

Post a Comment

I will approve your comments within a day or so at the latest. Please don't forget to check the 'Notify me' box so you will be notified when I reply to your comments.

Chris