Glass Layup Procedure

[Todd Young]

Do I have the procedure right....

1.   sand and clean surface 

2.   wet surface with micro 

3.   lay glass and wet again

4.   squeegee 

NOW BIG QUESTION

do you immediately lay the next ply or wait a certain amount or wait till cured?????

 

thanks

[Ron Springer]

Immediately ... the sooner the better. You want it to soak up any excess epoxy from the previous layer.

[Todd Young]

thanks Ron!!!!!!   also am I correct in assuming that when you but join...like the bulkhead to the side you have not glassed the edge and affix it directly to the side

[Voidhawk9]

Joins like bulkheads to fuselage side get floxed in place (make a nice little fillet) then 2" wide 2-BID tapes over the joins.

[Voidhawk9]

Here's some bulkheads with fresh tapes and peel-ply on them.

[Mike B]

For sanding I use 40 grit. Buy a sticky back roll. You can make whatever pattern you need to get that shape sanded.

When applying the micro I use a consistency that is easily spread but thick enough it won't run off the edge of the part. 

There is an old video on Youtube with Burt and Mike. That is the only instruction I've had prior to building. 

[A Bruce Hughes]

Always remember that there are times/places where you may later add more glass/epoxy.

You need to plan ahead and put pealply anywhere that may later get another layer of glass or some flox.

When the epoxy has hardened, you immediately rip off the pealply.  That

(1) avoids the necessity of sanding a hard surface later

(2) gives a pretty smooth surface without runs of liquid epoxy   

(3) may help lighten the whole project a little.

BEWARE:   pealply on a surface is nearly invisible so be SURE to have 1/2" of overhang of the pealply on each side to remind you that the pealply is there.   The FIRST thing that you do when you arrive at the work area on the next day  is to rip off any pelply  on surfaces.    The pealply may rip when you are removing it.   Be sure that you get ALL of the pealply on the surface.   Using pealply is dangerous if ANY is left where it should not be.

 

 

[Marc Zeitlin]

43 minutes ago, A Bruce Hughes said:

When the epoxy has hardened, you immediately rip off the pealply...The FIRST thing that you do when you arrive at the work area on the next day  is to rip off any pelply  on surfaces.

This is incorrect. Peel Ply should be left on a surface until just prior to the next layup, if there's going to be one. If not, then it doesn't matter when the peel ply is removed.

The act of pulling the peel ply off the surface breaks the epoxy bonds and ensures a high energy surface which greatly assists in adhesion of the next layer of epoxy. If you pull the peel ply off more than 2 - 24 hours prior to the next layup, the bonds will oxidize and you won't get the advantage of the peel plied surface - you'll just have to sand everything as you would if you didn't have peel ply. Many experts recommend sanding even if you DO have peel plied surfaces, just as belt and suspenders.

[Jon Matcho]

30 minutes ago, Marc Zeitlin said:

Many experts recommend sanding even if you DO have peel plied surfaces, just as belt and suspenders.

I have heard this as well, but disagree and consider it a waste of time.  Might as well not even use peel ply at all in this case.  The only time I'll sand after peel ply is if there's excess cured epoxy that needs to go before the next layer, or a contaminant of some sort (peanut butter, pizza, oil, etc).

[Jon Matcho]

I feel like I've left an opening for critique... 😉

1 hour ago, Jon Matcho said:

...a contaminant of some sort...

Waxy substances can be sanded away, and anything oily gets an acetone wipe-down.  

[Jon Matcho]

5 hours ago, Mike B said:

There is an old video on Youtube with Burt and Mike. That is the only instruction I've had prior to building. 

Yes!  Almost comical to watch, but all you really need.  The complete "official" instructions are in Chapter 3 - Education in the VariEze, Long-EZ, Cozy, AeroCanard, Defiant written plans.

 

[Voidhawk9]

Mike Arnold's series is educational as well, though does much further than needed for building from our plans unless you intend to make your own wheel pants, etc.

https://www.youtube.com/channel/UCVDILmX2ylWP1YLQmYi9nPw

[Marc Zeitlin]

5 hours ago, Jon Matcho said:

I have heard this as well, but disagree and consider it a waste of time.

And your disagreement is based on what research and data?

You may want to read through this paper:

https://depts.washington.edu/amtas/events/amtas_09fall/Flinn.pdf

Page 16 clearly shows higher surface energies with both Nylon and Polyester Peel Plies after sanding than "As Tooled". Is that NECESSARY? Don't know, but it does seem clear that sanding improves the surface energy created by removing the PP.

5 hours ago, Jon Matcho said:

Might as well not even use peel ply at all in this case.

Nonsense. At least with PP, you get a surface that when sanding, you won't damage the underlying fiber layers, and you don't need to sand as vigorously or as much. Still saves time and effort and gives a much smoother surface. And when you sand, you get better bonding, per the paper above.

[Jon Matcho]

1 hour ago, Marc Zeitlin said:

And your disagreement is based on what research and data?

A few things, such as:

1. Knowledge and formal education relating to the strengths of materials.
2. Paying attention to composite construction since I was in my teens.
3. Page 3-14 of the Long-EZ plans, Cozy plans, etc. (bolding is mine):  "Peel ply any area that will later be structurally attached to another fiberglass layup.  Once the dacron is peeled off, the surface is ready for another layup, without sanding."

1 hour ago, Marc Zeitlin said:

You may want to read through this paper:

https://depts.washington.edu/amtas/events/amtas_09fall/Flinn.pdf

That was a worthwhile presentation, thanks, but note that it reported results on Nylon and Polyester peel ply, but not what we should be using which is Dacron.  Yes, Dacron is a polyester, but is manufactured to be more durable than plain old polyester fabrics you'd wear to the disco.

1 hour ago, Marc Zeitlin said:

Nonsense. At least with PP, you get a surface that when sanding, you won't damage the underlying fiber layers, and you don't need to sand as vigorously or as much.

Good point -- I agree, except the need to throw out "nonsense" as you're missing my point:  Peel ply using Dacron and you will not need to sand to have a perfectly strong bond.  Alternatively, go nuts, put on your mask and sand away on the entire surface for an extra 0.1 in-lbs of strength.  That's not at all required in my opinion and nothing I would do or recommend FWIW.

I do typically sand the areas after ripping the peel ply, just to smooth any rough transitions.  

[Marc Zeitlin]

12 minutes ago, Jon Matcho said:

1. Page 3-14 of the Long-EZ plans, Cozy plans, etc. (bolding is mine):  "Peel ply any area that will later be structurally attached to another fiberglass layup.  Once the dacron is peeled off, the surface is ready for another layup, without sanding."

And they're correct - what I explicitly said was: "Many experts recommend sanding even if you DO have peel plied surfaces, just as belt and suspenders." I didn't say it was necessary - I said some folks recommend it, and it can't hurt. You said it was a waste of time, but that's not at all obvious.

13 minutes ago, Jon Matcho said:

That was a worthwhile presentation, thanks, but note that it reported results on Nylon and Polyester peel ply, but not what we should be using which is Dacron.  Yes, Dacron is a polyester, but is manufactured to be more durable than plain old polyester fabrics you'd wear to the disco.

The fact that the peel ply you buy from aircraft vendors is a bit thicker than what's used for clothing doesn't change the surface quality of the material. And there are some very thin polyester/Dacron materials available. The reason to get quality polyester/Dacron is not because it's thicker, but because it's guaranteed not to have unwanted sizing or coatings on it that may contaminate the layups. Since the presentation discussed the surface energy of polyester peel ply, it's directly applicable to what we do.

Now, as I said above - is the increase in surface energy NECESSARY? Don't know, and since there are a zillion airplanes out there flying with unbelievably crappy workmanship from a surface preparation standpoint, the answer is probably not. But if you want to know the BEST way to prepare the surface (necessary or not), it will include peel ply, sanding, and cleaning, all within a very short time period right before the next layups are applied. Peel ply alone is certainly acceptable, and so is sanding alone. But both together are a bit better.

[A Bruce Hughes]

8 hours ago, Marc Zeitlin said:

This is incorrect. Peel Ply should be left on a surface until just prior to the next layup, if there's going to be one. If not, then it doesn't matter when the peel ply is removed.

The act of pulling the peel ply off the surface breaks the epoxy bonds and ensures a high energy surface which greatly assists in adhesion of the next layer of epoxy. If you pull the peel ply off more than 2 - 24 hours prior to the next layup, the bonds will oxidize and you won't get the advantage of the peel plied surface - you'll just have to sand everything as you would if you didn't have peel ply. Many experts recommend sanding even if you DO have peel plied surfaces, just as belt and suspenders.

I have been doing the PealPly wrong.   At least anyone that reads this discussion will know that using peal ply is a good idea.

Keep a supply on hand and DO NOT think you can use Dacron from the local clothing store.

Bruce

 

[sixfivelrp]

On 11/26/2019 at 2:31 PM, Todd Young said:

Do I have the procedure right....

2.   wet surface with micro 

Correct me if I am wrong, but micro slurry foam to glass interfaces only, and not glass to glass. 

[Marc Zeitlin]

1 hour ago, sixfivelrp said:

Correct me if I am wrong, but micro slurry foam to glass interfaces only, and not glass to glass. 

You are correct. Micro ONLY on foam, not GtG.

[Mike B]

#5 - Use acetone to clean non-cured sticky from the squeegee, gloves, scissors, etc.

[macleodm3]

2 hours ago, Mike B said:

#5 - Use acetone to clean non-cured sticky from the squeegee, gloves, scissors, etc.

I like to use white vinegar since it works great for cleaning up MGS and West epoxies, and denatured alcohol for EZ-Poxy.