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Fiberglass epoxy question RV-9A slider

R

ron sterba

Well Known Member
I am in the process of building up my a lip over the top of my windshield and down the sides with the 1 1/2" fiberglass cloth. I have installed my first layer last night. For each additional layer do I have to let dry AND SAND each layer before I add the next layer? Or can I just keep adding layers?

Thanks Ron in Oregon
 
I am not up to that part yet, but you should be doing all the layers at once. If you let it cure then you have to scruff it up for the next layer to adhere. I'm sure someone more knowledgeable will chime in.

Jay
 
You can do it either way. I opted to apply the fiberglass over three sessions, with some sanding in between. I preferred this route because I didn't feel rushed and I could think about it a little between sessions.
 
I did all mine in one session also with two layers of CF in the mix around upper windshield, all on packing tape, next day popped it off and then sanded for a month on the bench, then Sika onto the plane.
 
Each time you put a new layer onto a CURED layer, you'll want to sand it down first - but you can lay up 3 or 4 layers at once, sure.

Make sure you mix a colorant into the epoxy if you don't want it clear, I made mine black.
 
Thanks,guys,I have peel ply. So sanding is still in my future,darn. OK I like the sikaflex idea since I used it on both windshield and canopy. Just knew ,just darn knew it that I should have posted earlier. That's what I get for my midnight lay up! Great ideas guys thanks. Got some carbon fiber so I'll use some of that too.

Always appreciative!

Ron in Oregon.
 
If the resin is still "green," you can put on another layer with no prep. If it is fully cured, it must be fully sanded for mechanical adhesion. Whether or not it is still "green" is variable based mostly upon which activator and the ambient temp while curing. a conservative rule is, If it is soft enough to dig a fingernail in, it is still green.

Generally, if you want to layer on previous hard layers, put the second layer on as soon as the first gets firm. I prefer wet layers. Sanding is a pain and chemical bonding is preferred over mechanical adhesion. multiple cured layers promotes excess resin. Wet layers are easier to keep tight.

the epoxy to plexi bond is quite poor. For my targa stripe, I layed up over packing tape and removed after curing. I then sanded and bonded it to the plexi with Urethane adhesive made for plexi bonding.

Larry
 
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And let your edge run long (aft on the aircraft) so you can cut the ragged edge to a clean finish and sand it down smooth.
 
Thanks Larry, thanks,my thoughts were running a little amuck about green. How many layers shouldI install? I bought rolls of 1", 1 1/2" & 2" of fiberglass with a hem sewn in on both edges. With one layer down and sanded ( need new thumb and forefinger). My next layer I wanted carbon fiber. Are there any special cutting procedures on this material. Mines in a roll one foot wide by 5 foot long and the strands are 3/32" wide and all going in same direction and a simple thread going 90 degrees across.( up & under & over ) it does not look like the weave of fiberglass cloth mating. Did I buy the wrong carbon fiber material? I am assuming the carbon fiber strands should run length wish across the windshield edge,yes/ no?

I at a rest stop on the interstate so I haven't been able to check the links the guys have sent in their threads. Maybe these questions might be in them,so forgive me for not checking them. Been a crazy busy day here in Oregon with the humidity getting up near 30% today.

Ron in Oregon RV9A
 
ron sterba said:
Thanks Larry, thanks,my thoughts were running a little amuck about green. How many layers shouldI install? I bought rolls of 1", 1 1/2" & 2" of fiberglass with a hem sewn in on both edges. With one layer down and sanded ( need new thumb and forefinger). My next layer I wanted carbon fiber. Are there any special cutting procedures on this material. Mines in a roll one foot wide by 5 foot long and the strands are 3/32" wide and all going in same direction and a simple thread going 90 degrees across.( up & under & over ) it does not look like the weave of fiberglass cloth mating. Did I buy the wrong carbon fiber material? I am assuming the carbon fiber strands should run length wish across the windshield edge,yes/ no?

I at a rest stop on the interstate so I haven't been able to check the links the guys have sent in their threads. Maybe these questions might be in them,so forgive me for not checking them. Been a crazy busy day here in Oregon with the humidity getting up near 30% today.

Ron in Oregon RV9A
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I bought a roll of CF, strands going the wrong way too, I just cut 3" lengths and laid them carefully the correct direction, me being a rookie at this FG stuff, came out great....and strong!
 
ron sterba said:
Thanks Larry, thanks,my thoughts were running a little amuck about green. How many layers shouldI install? I bought rolls of 1", 1 1/2" & 2" of fiberglass with a hem sewn in on both edges. With one layer down and sanded ( need new thumb and forefinger). My next layer I wanted carbon fiber. Are there any special cutting procedures on this material. Mines in a roll one foot wide by 5 foot long and the strands are 3/32" wide and all going in same direction and a simple thread going 90 degrees across.( up & under & over ) it does not look like the weave of fiberglass cloth mating. Did I buy the wrong carbon fiber material? I am assuming the carbon fiber strands should run length wish across the windshield edge,yes/ no?

I at a rest stop on the interstate so I haven't been able to check the links the guys have sent in their threads. Maybe these questions might be in them,so forgive me for not checking them. Been a crazy busy day here in Oregon with the humidity getting up near 30% today.

Ron in Oregon RV9A
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I don't have a slider, so don't know your application. For my Targa strip, I used three or four strips of glass, but it was a lightweight glass.

I am from Chicago, and would kill for a day with only 30% humidity:)

Larry
 
Well guys after driving for 4 hrs two in heavy traffic I got the right carbon fiber. After work last night I laid the carbon fiber strips and put peel ply over it. Yep it's 2:41 am Friday and just finished at 2 am. Well I tried laying the CF strips down to coat them with resin but they pulled apart at the edges so I wetted the layer from last night (sanded of course) with resin and then laid the CF into my brushed on resin ,then I tabbed up and down with a resin laiden 1" brush to coat throughly and then applied the peel ply material. Friday afternoon I check it. This procedure is really a art. Good night or morning.

Ron in Oregon RV9A
 
Whenever possible, avoid multiple layup sessions, and brushed resin application.

If tape (not always a good choice), cut all planned plies to length and stack them on a sheet of 4 mil plastic. Saturate with resin; just pour it on, then cover it with another plastic sheet. Give it a bit of time to soak while you work the resin around with a squeegee or roller. When it's all saturated, work all the excess resin out to the sides, away from the layup. Trim offf all the excess plastic, in particular the section of plastic/resin/plastic sandwich and throw it in the trash. You're left with a properly saturated stack of glass plies. Peel the plastic off one side, pick it up, flip it over, and place the stack on the work as desired. Now peel the remaining plastic, and stipple the air out from under the plies.

If using cloth, cut the plies a little larger than the finished part, stack 'em, wet 'em, cover, and saturate. Now draw the desired shape of the layup right on the plastic cover sheet. Trim to shape, cutting the entire sandwich, peel and place as before.
 
Dan, Mark, used both processes today and then used peel ply. I really liked the peel ply because it held my piece of CF and resin from sliding down the sides. When I pulled the peel ply off the resin surface was pretty level. I did find peel ply nice in that I was able to smooth the layer without pulling the CF out of position. Dan I'll try multiple pieces with resin poured over. Last night I had a mixture flash quickly with smoke and extremely heat. Yeah just set in on the ground away from everything and mixed one pump each. Flash batch was 3 pumps each of 105 and 205 west system. It warns on the 105 label. So I was aware of the condition but didn't expect. You learn. Temp was 82 in hangar. Today was near a 101. I think I need to use my 206 hardner. Again very pleased with results. I'll sand and place four more layers of 2 each. Sandwich in is good. I'll keep you updated.

Cheers
Ron in Oregon. Learned a lot in all the threads. Thanks guys.
 
DanH said:
Whenever possible, avoid multiple layup sessions, and brushed resin application.

If tape (not always a good choice), cut all planned plies to length and stack them on a sheet of 4 mil plastic. Saturate with resin; just pour it on, then cover it with another plastic sheet. Give it a bit of time to soak while you work the resin around with a squeegee or roller. When it's all saturated, work all the excess resin out to the sides, away from the layup. Trim offf all the excess plastic, in particular the section of plastic/resin/plastic sandwich and throw it in the trash. You're left with a properly saturated stack of glass plies. Peel the plastic off one side, pick it up, flip it over, and place the stack on the work as desired. Now peel the remaining plastic, and stipple the air out from under the plies.

If using cloth, cut the plies a little larger than the finished part, stack 'em, wet 'em, cover, and saturate. Now draw the desired shape of the layup right on the plastic cover sheet. Trim to shape, cutting the entire sandwich, peel and place as before.
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Dan's advice is 100% spot on. I learned the sage procedures above from 35 years of composite aircraft building. Read every one of Dan's words - twice.

Peel ply **only** when you have to - it's a crutch on non-bagged wet lay-ups.
 
Well guys I am getting this,,finally,last night's glass went in piece saturated as Dan mentioned and you'll backing up Dan. Dan that website is educational and works well here.peel ply ,wow nice finish. Sides stayed in place,that was nice. Did have a couple of pockets with no resin under the peel ply. Is this because the resin ran??? Should I just sand these shinning holes and put a leveling layer of resin and 403 micro fiber? Then proceed with the next layer of Carbon Fiber? It appears the wrap over is getting pretty smooth.

Another note. Check this app. Freeflightradar24. All words run together.
You'll ADSB locations right in your phone. That's the limited free version but I think I paid $4 for the app that tells it all about the plane,speed altitude.where,going to,eta, and 3D of Google Earth of the pilot sees. You can even see your buddy get a Bourne and head toward your airport.bunch more stuff.

Ron in Oregon
 
Dan the larger pieces sandwiched between the plastic sheets and squeezed the excess out to the sides with a thin stick worked PERFECTLY! Lay up was so easy. What a learning lesson guys thanks!

Ron in Oregon RV9A
 
deek said:
Peel ply **only** when you have to - it's a crutch on non-bagged wet lay-ups.
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I very much disagree, but I am willing to hear why you think it is bad to use it. The only one I can think of is the cost, and it costs just about nothing. In fact iot is often free if you get some left over scraps from a friend who did a cover job on a fabric airplane.

The weave in the cloth typically used by home builders (8-9 oz) will not be filled with resin (particularly on vertical surfaces) unless you apply a final wet coat of resin and cover with peel ply.
The added benefit is that if you discover an area that you want to add a little more too afterwards (as Mike already mentioned) is that the surface is ready for more layups or filler without doing any prep. sanding.
 
You'r right, the cost of peel ply is negligible. I used a lot of peel ply on the first few airplanes, but once you develop some expertise in wet lay lay-ups peel ply can cause more work & issues than the trivial convenience of not sanding for additional layups:

• it's almost impossible to see through the peel ply to inspect for resin rich/lean
• air bubbles are common on anything except planar surfaces
• peel ply stippling tends to disturb the "flatness" of thick layups
• I've seen several instances where the builder forgot to remove the peel ply and made the next layup on top of the peel ply (winglet to wing structural layup)
• it's much easier to prep glass for fill if you are scuffing the layup surface; it can be hard to get through the "bump" created by peel play thereby increasing your sand and fill time.

I've done A LOT of glass work on RV's for friends who loathe epoxy and glass, and haven't found much opportunity to use peel ply except on major cowling mods. I never use peel ply on the canopy, just use unidirectional as the outer ply (the selvage edge intact) over the top of the BID plys.

I didn't say don't use peel ply, just use it judiciously, ie, where you know an additional layup will be accomplished like a corner tape.

All the above applies to non-bagged parts - bagging is a different animal.
 
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deek said:
You'r right, the cost of peel ply is negligible. I used a lot of peel ply on the first few airplanes, but once you develop some expertise in wet lay lay-ups peel ply can cause work & issues than the trivial convenience of not sanding for additional layups:

• it's almost impossible to see through the peel ply to inspect for resin rich/lean
• air bubbles are common on anything except planar surfaces
• peel ply stippling tends to disturb the "flatness" of thick layups
• I've seen several instances where the builder forgot to remove the peel ply and made the next layup on top of the peel ply (winglet to wing structural layup)
• it's much easier to prep glass for fill if you are scuffing the layup surface; it can be hard to get through the "bump" created by peel play thereby increasing your sand and fill time.

I've done A LOT of glass work on RV's for friends who loathe epoxy and glass, and haven't found much opportunity to use peel ply except on major cowling mods. I never use peel ply on the canopy, just use unidirectional as the outer ply (the selvage edge intact) over the top of the BID plys.

I didn't say don't use peel ply, just use it judiciously, ie, where you know an additional layup will be accomplished like a corner tape.

All the above applies to non-bagged parts - bagging is a different animal.
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+1 This mirrors my experiences with peel ply precisely. Maybe, I am using it wrong or don't have the right product. PP certainly has it's place, but not a universal tool that overcomes layup issues. Particularly, if you want to end up with an even surface with smooth contours for making a multi curved part, which is exactly why I use glass anyway. It just seems to make more sanding work to smooth out the overlaps (heavy resin areas) since it is lousy for adapting to contours. If there is a peel ply what will drape like a twill, please recommend.

Like Scott mentions, it certainly has it's place for low crown work and/or where you can't sand blast to get tooth in the weave voids for finish work.

If it is much more than 20g of 105 resin, I don't have good results with fast hardener. A steady relaxed pace with consistent mixed resin properties allows better layup technique.
 
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ron sterba said:
Dan the larger pieces sandwiched between the plastic sheets and squeezed the excess out to the sides with a thin stick worked PERFECTLY! Lay up was so easy. What a learning lesson guys thanks!

Ron in Oregon RV9A
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You'll like it even better with a roller.
 
Dan, I think I have one piece to lay up at the corner. 6" each direction. I have a small roller. The previous posts on peel ply diffently go along the lines about the bumps I have observed. Ended up sanding them level but what a pain. I did do the multi layer lay up, It worked fine, resin stayed green because of cooler temps yesterday. I can say that when I put the 1 1/2" wide five foot piece across the top with out the peel ply I got a smooth ( not pockets of resin ) consistent layer with no oz zing. Sanding has taken a toll on my shoulder. The pain each night, ouch, Wish vans would come out with a easy to glue on strip over the top and sides . My front of the windshield came out good. Used the techque on glueing sandpaper to 6" round plastic pipe coupling. Then back and forth. Worked great. Hopefully it will sand out straight today. Body filler ( lite) might be all that's needed now. One of the guys mentioned a final brush on wet coat, say if the final goes on and I still show a little webbing in the coat can a second wet coat be brushed on webbing spot or do I coat it all again???

Ron in Oregon
 
deek said:
You'r right, the cost of peel ply is negligible. I used a lot of peel ply on the first few airplanes, but once you develop some expertise in wet lay lay-ups peel ply can cause more work & issues than the trivial convenience of not sanding for additional layups:

? it's almost impossible to see through the peel ply to inspect for resin rich/lean
? air bubbles are common on anything except planar surfaces
? peel ply stippling tends to disturb the "flatness" of thick layups
? I've seen several instances where the builder forgot to remove the peel ply and made the next layup on top of the peel ply (winglet to wing structural layup)
? it's much easier to prep glass for fill if you are scuffing the layup surface; it can be hard to get through the "bump" created by peel play thereby increasing your sand and fill time.

I've done A LOT of glass work on RV's for friends who loathe epoxy and glass, and haven't found much opportunity to use peel ply except on major cowling mods. I never use peel ply on the canopy, just use unidirectional as the outer ply (the selvage edge intact) over the top of the BID plys.

I didn't say don't use peel ply, just use it judiciously, ie, where you know an additional layup will be accomplished like a corner tape.

All the above applies to non-bagged parts - bagging is a different animal.
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The problem with your idea is that most builders don't develop much expertise because unless doing major cowl modifications, etc. there is not that much glass work to do.

For this reason I still disagree with your recommendation.
 
deek said:
peel ply can cause more work & issues than the trivial convenience of not sanding for additional layups------snip------
I didn't say don't use peel ply, just use it judiciously, ie, where you know an additional layup will be accomplished like a corner tape.
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ron sterba said:
I am in the process of building up my a lip over the top of my windshield and down the sides with the 1 1/2" fiberglass cloth. I have installed my first layer last night. For each additional layer do I have to let dry AND SAND each layer before I add the next layer? Or can I just keep adding layers?

Thanks Ron in Oregon
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Mike S said:
If you do it layer by layer, you can use peel ply to give a usable surface to the hardened layer.

http://www.clcboats.com/shoptips/epoxy_and_fiberglass/peel-ply-release-fabric.html
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Deek-------lots of rabbits running for cover here------go back and read the OP and my suggestion to address the question asked therein.

Your many examples of issues where peel ply is not the best choice are correct, but pretty much totally off the subject of this thread. Your last sentence above is in agreement with what I and Scott have said, and is directly on target of the thread.
 
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Mike S said:
---go back and read the OP and my suggestion to address the question asked therein.
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The OP asked if he needs to sand between the addition of individual layers. The answer is yes, sand or peel ply. Basic rule for any glass work; given cured epoxy, a sanded or fractured surface is necessary before trying to subsequently bond to it.

However, in this application, it is artless to add one ply at a time, which makes the question moot.

BTW, put me with Deek here. I don't use peel ply without specific reason, and I can't see much reason to use it on a windshield bow fairing.
 
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