<<In a message dated 10/29/2004 6:48:30 PM Central Daylight Time, [EMAIL PROTECTED] writes: I noticed in the original post that you were using West Systems 205 hardener. Perhaps you meant to say 206 hardener. The 206 hardener is appropriate for vac bagging. The use of 205 (much faster acting) hardener could cause a few problems;>>
Yes, my mistake. It's 206. The experience you've shared is very instructive. And I'm equally puzzled by the outcome. But it's very real. The epoxy is mixed in a cup, not a plate. There's no skin. It's nowhere near gelled by the time it goes in the bag. I don't warm the epoxy at all. RT in the basement in Oklahoma is around 75 to 80 most of the time. I'm using the West 5:1 pumps and the leftover in the cup cures up very nicely by the next AM. The problem has occurred in natural and painted mylars. It appears predominantly on the upper surface. The breather is in contact with the lower foam bed. The core and mylars lie in the lower bed and so are not in contact with any previously used breather. I typically don't use a roller but use a curved vinyl squeegee to pull out the excess resin. As a reality check, I had to replace the stab on my XP3 and the bagged balsa part came out at 5g - a titch under the factory version. And that's with a beveled 1/64" ply strip reinforcing the TE. I never get any of these defects in glassed balsa parts, even with very light, soft balsa. It's possible I've jumped to a conclusion here with one lucky shot but the overall quality was better than any of the parts I've done lately. I'll keep trying things. I've looked over your video quite a few times to see what I'm missing but no luck so far.... One clarification, most of the foam I'm using is Foamular 150 with light glass and carbon uni. These defects sometimes appear just over the foam, sometimes over the foam and the uni. Since the glass surface in the 'dent' is smooth, well wet-out and well bonded to the core, it's getting some consolidation pressure in the bag. That's why I suspect trapped air or volatiles of some sort. The parts are still usable for what I'm trying. I'm using Dow 25psi blue foam and heavier glass for some work next week and will see how that goes. Perhaps I'm just crushing the foam with too much pressure for 150? Your experience is appreciated. If the result doesn't add up based on all the work you've done, we'll keep looking for other solutions. Thanks, - Dave R RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
