Saturday, July 18, 2015

TIPS ON MAKING MICARTA


Knife scales made from Micarta have become popular over the last couple of decades.  Other synthetics are also making inroads and replacing traditional wood or antler knife handles.  Micarta is a process by which layers of organic fabrics (paper, linen, canvas etc.) are impregnated with epoxy resin and then sandwiched together under great pressure to form a stable and rock-hard slab.  Micarta slabs can be one color or a collage of colors giving them an array of appearances and textures.  It’s not all that difficult to make your own Micarta but having made dozens of Micarta slabs allow me to offer some tips that will make the process easier and less wasteful.


1) Making Micarta is a smelly and gooey process and the epoxy fumes are toxic.  Always make Micarta in an open, well-ventilated space.  I wear a respirator and make my Micarta outside under the open shed where I make my knives and bows.  Even though I’m wearing a respirator I still have a large fan blowing behind me to push the fumes away.  I have known people who became quite ill when they attempted to make Micarta in an enclosed space and did not use a respirator.
2) Before you start making your Micarta slab get everything you’ll need and place it near or on your work table.  Since you are working with epoxy you’ll need to work quickly.  However, I’m going to explain a method that I use that will greatly extend the time needed to make your Micarta and at the same time will not sacrifice the hardening qualities of the epoxy resin.


3) These are the materials I use:
          a) 2 ½” X 12” strips of construction paper, 50-80 pound cardstock, linen or canvas sheets.  Burlap can be used as well.
          b) Nitrile gloves.  I use three pair for each Micarta making session.
          c) Mixing tool.  I use a disposable plastic knife.
          d) Wax paper
          e) Respirator
          f) Paper cup.  I use two or three cups per session.
          g) Two 1”x 4” x 15” pine boards
          h) Bench mounted vise
          i) Four C-clamps
          j) Electronic kitchen scale
          k) Epoxy resin and hardener. I purchase epoxy by the gallon at Home Depot.
I place a large piece of cardboard on my workbench to keep the epoxy from spilling onto the bench while I’m working.

The epoxy calls for ten drops of hardener for each ounce of resin.  A typical paper Micarta slab will use about four ounces of epoxy while linen or canvas Micarta will use as much as six or even seven ounces.


IMPORTANT: When mixed according to directions the epoxy begins to harden in eight to eleven minutes depending on the ambient temperature.  That does not give you much time to work.  Now most hobbyists put less than the directed amount of hardener because they want to extend the time limit.  But this is not good technique and the tactic is unnecessary since one can still follow the manufacturer’s directions and obtain top quality Micarta but at the same time not be so rushed.  So here is what I do:
          a) Always measure out the amount of resin you intend to use. DON’T GUESS.  That is bad technique.
          b) For paper Micarta I’ll use two paper cups each pre-filled with two fluid ounces of resin.  I will not add the hardener until I’m ready to start.  When I’m making linen or canvas Micarta I will pre-fill three paper cups with 2-ounces each of resin.
          c) I will put two pairs of Nitrile gloves on since one pair is going to get all slimed with epoxy and I need a clean pair underneath when I fold the wax paper over the slab in order to form a neat rectangular package.
          d) When I am ready and all the materials are in place I will put twenty drops of hardener in the first cup and then mix the solution with my plastic knife.  I have already placed a sheet of wax paper on the cardboard and I have the sheets of fabric ready for use.
          e) Since I am only working with two ounces from each cup I have more than enough time to use the allocated epoxy to start the job.  Let’s assume I’m making Micarta from construction paper—but the same process works for all fabrics.
          f) I place the first paper sheet on the wax paper and then saturate it with epoxy.  I’ll then flip the sheet over and saturate the other side with epoxy.  Then I place another sheet on the first sheet and saturate it with epoxy.  The process continues until I finish the first 2-ounces of epoxy in the paper cup.
          g) When the first 2-ounces are gone I’ll put a clean sheet of construction paper (or linen or canvas or cardstock) on the last saturated sheet and then quickly mix in twenty drops of hardener into the next cup that is already filled with resin.  Then I continue the process.  Mixing in twenty drops in the second cup takes about ten seconds.


As mentioned, 4-ounces of epoxy usually suffice for a ½-inch slab of construction paper or cardstock.  After you’ve completed saturating the sheets then remove the top pair of Nitrile gloves and then carefully wrap the wax paper around the entire package.  I always keep an extra pair of Nitrile gloves next to me in case I need to remove one pair and quickly place another clean pair over the pair that is next to my skin.  It’s a safeguard that I suggest you get in the habit of employing.  Now some people build forms in which to place the package.  I find that step unnecessary because I then place the completed package between my two pieces of wood and then, holding the wood/package firmly, I slip it into my bench vise.  This serves the same purpose of a form because I can then quickly tighten the vise to hold the wood/epoxy package in place.  It always works.  I then begin placing my C-clamps on the wood/package carefully tightening the clamps (and further tightening the vise) until everything is absolutely secure.  Some people claim that one should not tighten the wood/package too much but I find their reasons unconvincing.  If you have followed the product directions and added the proper amount of hardener drops AND you have followed my directions and worked with only 2-ounces of epoxy at a time then by the time you place the wood/package into the vise it will already be very hot!  In other words, it is already hardening.  There will be essentially no spilling or leaking of the epoxy out and you will have an extremely hard slab in about 24-hours time.


I leave the wood/package in the vise (with the C-clamps attached) for at least one full day.  After which I’ll remove the wood/package from the vise and then remove the C-clamps.  I’ll remove as much of the wax paper as possible and, using a coping saw I’ll trim the edge of the slab to get a peek of the finished product.  I always keep about ten or twelve Micarta slabs ready to use and when a blade is ready I’ll select a slab.  REMEMBER that working with a completed Micarta package is also dangerous if you don’t wear a respirator.  Like before I shape the Micarta scales outside with my large fan next to my small belt sander blowing all the epoxy particulate away.  NEVER take chances around Micarta either when making the package or when sanding the scales.  Micarta made properly will probably last longer than the knife blade itself.  It will not shrink or expand and is essentially waterproof.  I often “paint” the completed and attached scales with a layer of 5-minute epoxy.  This makes the handles quite smooth and some people like a rougher feel to their knife handles.  But I’ve never liked knife scales with knurls or grooves or deep checkering or finger channels because in a working situation you will require a handle that is designed to allow you to adjust your grip in order to lessen fatigue and injury to the skin.  So I’m just fine with smooth grips.  Years of experience has shown me what works and what amounts to fad.

2 comments:

  1. Excellent write up on your process, thank you very much for taking the time to do it.
    I just found your blog the other day, but it looks like a lot of good reading is to be had here.

    ReplyDelete
    Replies
    1. Thanks, Justin. It's time for me to get busy posting articles for the coming fall.

      Delete