New guy... epoxy/lay-up question

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#1

I’ve been working with PER’s off and on for over 30 years building my own plugs/molds, etc. For various reasons, though, it’s time/necessary to switch to epoxies. I understand that they have greater mechanical/physical properties, but I have no prior experience with them.
I’ve looked at US Composites, Mr Fiberglass and RAKA private-label systems and (based on supplied information) they all appear to be Reichold Epotuf 37-127, but it’s only rated to around 150-160* F…fine for most stuff, but too close for comfort for this particular project (actual measured temperatures around 145* F) which will most likely use Aeropoxy due to its’ higher Tg rating (196* +/-).

I have several smaller projects planned first to get used to the different resin system, but I’m really thinking ahead toward a rather large hood, approximately 60"w x 66"l,…right around 27 sq/ft… with a 3"w x 1 1/4"d perimeter frame bonded underneath to allow bolt-on mounting. This is for a street application. Although relatively flat (very gently arced), it has three crowns running along its’ length, and an integral scoop, that should contribute somewhat to overall skin stiffness. What I’m wrestling with is a lay-up schedule. If at all possible, I’d really like to keep the skin’s total weight to 10-11 ounces sq/ft, using E-glass. My thoughts are:

  1. Duratec surfacer (gelcoat substitution)
  2. 4 oz plain weave (print blocker)
  3. 7.5 oz plain weave
  4. 1.5 oz stitched-mat (epoxy compatible)
  5. 10 oz plain weave

Possibly some Divinycell, or similar core material, as well.

Finally, vacuum bag the assembly.

I’ve yet to lay-up test coupons, which I WILL do… but am I being optimistic?

Thanks,

Dutch

http://www.reichhold.com/docs/bulletin/Epotuf%2037-127%20(37127-00).pdf

http://www.ptm-w.com/dynamicdata/data/docs/aeropoxy%20pr2032%20bulletin.pdf

#2

Jeffo offers a few room temperature cure epoxies that will withstand up to 280 degrees.

#3

Last time I browsed through Jeffco’s listings the only high(er) temp resin that stood out was #1420, but it required a post-cure. I’ll definitely look again.

Thanks.

#4

Also, in the above lay-up schedule,… I referenced a layer of chopped mat. Old habits are gonna die hard. For the same weight (and less resin) the layer of chopped mat could just as easily be replaced with two layers of 10 oz cloth (on a 45* bias?). Or what about a layer of biaxial? What are their wet-out characteristics?

Wanting to do this the smart way.

The question still remains… is 10 oz/sq ft of 'glass/resin a reasonable schedule?