Date: Mon, 20 May 1996 20:02:38 From: JRaerocad@gnn.com (Jeff Russell) Subject: COZY: Peel ply Rob Atencio writes: > Now I put the peel ply on the entire aft surface as called out. I > continued to wet this out as I have done with the fiberglass, > until all signs of air pockets were gone. Here at AeroCad and Alexander's SportAir Center, we teach using peel-ply only when necessary. When vacuum bagging, or underneath skins for a glass to glass bond, or where secondary bonding of other skins will be applied is peel-ply used. Another good place to use the stuff is over tape glass edges to make a transition from a blunt edge. If you make all of your lay-ups like that (wetting out peel-ply like fiber glass) you are guaranteed to be heavier than what the part would be without the use of peel-ply. People have been told to peel-ply everything to give a smother finish so that finishing goes faster. WRONG. This WILL only gain more empty weight to your pretty bird. If you use the peel-ply to strip out more resin AFTER your done with your normal lay-up, this can save weight BUT be careful! You can strip out to much. > I applied the peel-ply believing what I thought might have been too > much epoxy to eliminate all those air pockets. Then I find all those spots. > Next I wonder if this is the way it is supposed be and unavoidable, > because most of the surface doesn't contain these spots, just certain patches. > Could someone enlighten this poor neophyte fiberglasser on > just what a peel-plied surface is supposed to look like? Sounds like you have it about the best you can get unless you vacuum bag. Try some small panel test pieces. (Weight and Quality check) One like you first made. 2nd without peel-ply 3rd with peel-ply to take more resin out 4th (If possible) vacuum bag What you will find is the 2nd and 4th will be the best quality without being too lean and with the lightest weight. > Should I take more time to ensure ALL the air is out (which I thought I had)? > Should I stop worrying and continue on? Or should I hang it up now and find > some other use of my time like mowing the lawn? Lawn mowing won't build airplanes unless its your job and it pays for your bird! It might work as a large blender to make big batches of dry micro! AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 910-961-2238 E-mail: JRaerocad@gnn.com From: ratencio@coastalnet.com Date: Mon, 20 May 96 15:31:37 -0500 Subject: COZY: Peel-Ply Surface Finish Okay all you fiberglass layup experts out there. Being that this is the first time I have ever worked with fiberglass, I'm not too sure of just what the appearance of a good layup looks like. I just completed glassing both sides of the instrument panel and got my first taste of using peel ply. Here's what I did. I did the layups as I normally would...brush...stipple...stipple...stipple...and everything looked good. Now I put the peel ply on the entire aft surface as called out. I continued to wet this out as I have done with the fiberglass, until all signs of air pockets were gone. I gave my self a pat on the back for the fine job I had done. - Next day - I go and visit my creation fromt the previous day and all looks nice and pretty. Let's remove the peel ply and have a look and the smooth surface finish created by this process. I peel away all the peel-ply and find that there are now thousands of air pockets (white spots) on this nice smooth finish. Now I'm wondering what went wrong. I applied the peel-ply believing what I thought might have been too much epoxy to eliminate all those air pockets. Then I find all those spots. Next I wonder if this is the way it is supposed be and unavoidable, because most of the surface doesn't contain these spots, just certain patches. Could someone enlighten this poor neophyte fiberglasser on just what a peel-plied surface is supposed to look like? Should I take more time to ensure ALL the air is out (which I thought I had)? Should I stop worrying and continue on? Or should I hang it up now and find some other use of my time like mowing the lawn? ----------------------------------------------------------- Rob Atencio E-Mail: ratencio@coastalnet.com ----------------------------------------------------------- Date: Tue, 21 May 1996 11:21:06 From: JRaerocad@gnn.com (Jeff Russell) Subject: Re: COZY: Peel-Ply Surface Finish >Jim Hocut writes: >I disagree with this part, for the same reason as stated by Jeff > and some others. By adding resin to get the peel ply to wet out you're > guaranteed a heavier part. With patience and slight pressure you can usually > get peel ply to wet due to the excess resin already in the glass, thereby > resulting in a lighter part. Try using some heat from a hair dryer to thin the resin under the applied peel ply. This is how you can wet out peel-ply without using more resin. Be carefull to not take out to much!!! AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 910-961-2238 E-mail: JRaerocad@gnn.com Date: Tue, 21 May 1996 08:41:09 -0400 From: Jim Hocut Subject: Re: COZY: Peel-Ply Surface Finish At 08:28 AM 5/21/96 EST, Bob Misterka wrote: > ..... > If you need to peel ply, lay the peel ply over the layup and > add a bit more epoxy (only enough to wet out the peel ply) > and again sqeegee to spread the epoxy and wet out the peel > ply. The result should be a smooth surface. Inevitably you > will get some air pockets under the peel ply but there > shouldn't be too many and you can sand them smooth on the > cured layup. > ...... I disagree with this part, for the same reason as stated by Jeff and some others. By adding resin to get the peel ply to wet out you're guaranteed a heavier part. With patience and slight pressure you can usually get peel ply to wet due to the excess resin already in the glass, thereby resulting in a lighter part. Jim Hocut jhocut@mindspring.com Date: Tue, 21 May 96 08:28:05 EST From: MISTER@neesnet.com Subject: Re: COZY: Peel-Ply Surface Finish Rob Atencio writes: >>Could someone enlighten this poor neophyte fiberglasser on just what a peel-plied surface is supposed to look like? ETC.<<< Rob, it sounds to me like you're using the wrong technique. I would suggest that you get a copy of the Burt Rutan video tape on building composite airplanes. I forget the exact title but it is a very good primer on the proper technique for doing composite sandwich construction. When you make your parts, first pour some micro slurry over the foam using a Thalco squeegee (available from Wicks) to spread it out. Then cover with the first layer of glass, pour some epoxy on the fiberglass and again use a Thalco squeegee to spread the goo over the glass. Add layers of glass and more epoxy as needed to throughly wet out the glass. Use the squeegee to move the epoxy around. When your final layer of glass is on use the sqeegee to remove any excess epoxy. In a properly wetted out layup, as you drag the squeegee lightly across the layup you shouldn't dredge up a bump of epoxy. Stippling is only necessary if you have an area that refuses to wet out. If you need to peel ply, lay the peel ply over the layup and add a bit more epoxy (only enough to wet out the peel ply) and again sqeegee to spread the epoxy and wet out the peel ply. The result should be a smooth surface. Inevitably you will get some air pockets under the peel ply but there shouldn't be too many and you can sand them smooth on the cured layup. I'd recommend using peel ply on your corner tapes or on surfaces you feel need to be really smooth. I wouldn't peel ply everything as some have suggested. It can add too much weight. I prefer using the slow hardeners, especially RAE slow. It gives you more time to work on the piece especially if the layout is big and the temperatures warm. Definitely try to get a copy of the Rutan tape. Hope this helps and hang in there. Bob Misterka N342RM From: Dick_Finn@em.fcnbd.com Date: Tue, 21 May 1996 10:20:07 -0500 Subject: Re[2]: COZY: Peel-Ply Surface Finish