Tuesday, December 5, 2017

100 Best--Chapter 13

Best Laminating and Fiberglass Materials

Just as important as the products is following the instructions and a few tips:

  • ALWAYS test the adhesive on something similar before diving into an important project. I have had experienced epoxies mis-labled, where resin was packaged as hardener and it never cured; I got  to scrape up 1/4-acre of honey-like glue, followed by wiping up the residue with gallons xylene. 
  • Confirm the cure time at the relevant temperature and humidity, remembering that fast-cure epoxies can exotherm (get hot) and cure very fast if mixed in batches over about 1/2 ounce.
  • Make sure you have what you need for clean-up. For epoxy, vinegar will neutralized the curing process and will take it off hard surfaces so long as it is still sticky (follow with soap and water). 
  • Surface prep is most of the battle. Clean first, then sand. Never try to sand off dirt or amine blush.
  • Jamestown Distributing. They will have everything you need at a reasonable overall cost. 
  • Read a few books. West Systems has some good short guides. It's not magic, but there are a lot of tricks of the trade.
  • Work neat and change gloves often. Disposable brushes are indescribable. If something is getting sticky, toss it. On big jobs, have a helper mix epoxy and cut glass; this makes for much neater work. If working alone, pre-cut most of the glass.
76. West Systems 105/205 Fast Cure. The work horse for most projects, the only shortcoming is that in warm weather it will exotherm fast. Large pots that cannot be spread in a few minutes will get warm, and even thick laminates will heat up. Too fast for epoxy sealing holes. Good in cool weather, though. If you have a fall or spring project, and it will be in the 50s at night, just the ticket.

77. West Systems 206 Slow Hardener. Works in warm weather. Also good for filling screw holes. I do NOT recommend the extra slow hardener. It is vulnerable to humidity and the mix must be exact.

78. Fumed Silica / Cabosil M-5. West sells this stuff for userous prices. Instead, buy a 10-pound bag and you will be set for a lifetime. Excellent for bonding and fillets, and usable to fairing if you can fet to it with a power sander. Hard to sand, so not good for large fairing projects.

 79. Laminating Roller. Never take on a significant job without a way of forcing the resin through the glass. Vacuum bagging is nice, but a good roller can get you most of the way there with a lot less fuss. Don't be afraid to roll pretty hard, pushing out air and excess resin. You will save real dollars on resin and get a stronger, lighter result with better bonding.

 80. 17-ounce Biaxial Fiberglass Cloth. Nearly 3 times as heavy as typical 6-ounce cloth and often easier to handle, it is MUCH stronger than mat (which does not work with epoxy) or glass cloth, because the fibers are oriented in the plain and not crimped or oddly directed. Use this in combination with 13-ounce uni-directional cloth in the direction real tensile strength is needed, and you can build some strong stuff.

17-ounce biaxial cloth is the best for tabbing braces. F-24 trimaran centerboard case on the right, hull on the left, depth sounder cable over the top.

I'm not really a fan of carbon fiber or Kevlar. The problem is that these materials are so much stiller than glass, they will carry the entire load. This means the bonding much be very good and that there must be enough carbon to carry the load, since it won't share. You can't reinforce rope with bungee cord, can you? The rope will break before the bungee does a thing.

80a. DuckWorks Studs. Through not technically fiberglass stuff, they go on with thicken epoxy and sometimes glass, so I'll add them here.

 Glue on Studs Instead of drilling a hole through the hull, grind a spot clean, de-grease the stud, and press it into a big blob of thickened epoxy so that it comes through the holes and interlocks. They will hold hundreds of pounds, but a 50-pound working load is quite safe. Then mount what ever you have with a knob or 1/4-inch USS nut. I've used these to hold down air conditioners, heavy inverters, and mount strips for rows of heavily loaded hooks. Marine contractors love them but few sailors know them.

Drilling all those holes in the hull would have been trouble! And I can remove the hooks and change them any time I like. Pretty slick.

There are lots more tips. Start with a small project, like a box or cover for something. Something removable that you can do over if it sucks. In fact, repairs are not the best place to start. And don't forget to scrub off the amine blush before painting and if you are not with in the green re-coat window.

Build something amazing!

PDQ 32/34 transoms before paint. Biax for the main structure, pre-laminated sheet for the step, 6-ounce finish cloth for the surface layer, and lots of sanding. Very strong; I ht some dock just to be sure ;).

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