Carbon Sheet
by Jake on Mar.15, 2007, under One Meter
With my new sails sitting on my pool table, I decided I would finalize some of the rigging details in the next week or so. In order to do that, I needed some flat carbon material from which to make spreaders and a mast crane to replace the light-plywood I used for the test. At the same time, I wanted to test out some of the mold release waxes I have before I rely on them in the hull molds (I can continue to use the PVA but it adds almost two hours to each molding cycle). I’ve had two small .25″ pieces of plate glass I found when I moved into this house 8 years ago so I decided to use those to sandwich some carbon in and vacuum bag to a cure. I first put three coats of “Mold Release” wax on each glass plate and then took 5 layers of (I believe) ~5oz carbon fabric with alternating patterns, poured about 1oz of epoxy into the center, padded with polystuffing, inserted into a 1 gallon ziplock bag, and pulled a 20in/hg vacuum on it. After about an hour under the heat lamp, I disassembled the vacuum setup and found the glass was pretty firmly adhered to the carbon. We won’t be using that wax again!
After trying shots of air pressure with no success, I tried to insert a wooden wedge and tap lightly but one of the pieces of glass finally broke. I then resorted to a tool to give the glass a little more incentive; a hammer. After breaking the glass on both sides into pieces, I was able to scrape off the remainder and ended up with a relatively unharmed piece of carbon. It’s under 1/16″ and incredibly stiff – this stuff is amazing. I can probably get away with just three layers for these components. I think in this case, I’ll forgo the waxes and just use a plastic sheet between the glass and the lamination…I’ll get some bigger 12″x12″ glass for the next round now that I know this is viable.
Originally uploaded by Team Seacats.
March 15th, 2007 on 10:07 PM
Jake, I have tried a lot of the fancy mold release so called High tech stuff. Lost a couple of very expensive molds with them. I have always fallen back to the basics Johnson Paste Wax (Walmart, yellow can) Three or four coats on a fresh mold, one light spray pva and good to go. After a couple of pulls and the mold will season and all is required is one or two fresh coats of wax. The key is to apply the wax by hand let sit half a day hand buff, then reapply. Works for me for many years on small and bus size molds.
Carl
March 16th, 2007 on 9:49 AM
Carl, excellent – thanks! I was hoping that someone with experience would chime in and lend some advice.
March 17th, 2007 on 12:37 AM
I don’t think any type of release could have helped you in that layup. It looks like the glass you had was smaller than your reinforcements and it looks like the your part just got a real good mechanical grip on your glass.
Whenever I have a need for some flat carbon sheets, I use a sliding glass door I trash picked a few years ago and do the layup on that. The piece is smaller than the glass. Then I usually put, on top of the layup, a piece of peel ply, then the absorbent mat, then my bagging material. Then I use that gummy sticky tack as a sealant in between the glass and the plastic. The Peel ply gives it a nice surface to do secondary bonding. If I need both sides to be shiny, I just use the release film, or bag material with a few very small holes in it, instead of the peel ply layer. works great!
Oh, and also, did you try water? PVA wax just melts away with h2o.