Nylon vs. polyester peel ply

[tomherrick]

I've read a couple of articles by groups who have done some engineering tests on the secondary bonding of epoxy laminations using nylon and polyester peel plies. According to those studies, the nylon peel ply produced a less than adequate surface for secondary bonding. These studies were done by the FAA and McDonnell Douglas; perhaps their criteria were much higher than building a high-quality recreational boat.

Any thoughts on whether or not nylon peel ply should be avoided?

[CatBuilder]

You should always sand your secondary bond area, so it doesn't matter which you use.

[tomherrick]

Is one material easier than the other to remove? Is there a recommended weave or weight to the material? Should one use less vacuum-generated pressure when laminating with peel ply?

[CatBuilder]

Yes, there is definitely a big difference between weights of peel ply and ease of removal.

If bagging (or infusing) with polyester peel ply, you will want to get Econoply E, which is the heavier 2.75oz polyester cloth.

I once had a roll of Econoply J (1.6oz) delivered to me at the supplier's error. I put quite a bit of it into an infusion and it took me 3 days of very hard labor to remove it from the part.

Always go with the thicker peel ply if you are concerned with removing it. The thin stuff just shreds apart in your hands. I found a good test to see if you have the right peel ply is this: Grab it in your hands and try to rip it. If it can be ripped, it's the wrong one.

The stuff you want for bagging or infusing is Airtech's Econoply E - 2.75oz, polyester.

If you are using a nylon release material, it will release even better, but at much greater cost.

[tomherrick]

Thanks, CatBuilder, for all the info. I'm torn between the Econo E and the nylon Econostitch which is about 18% higher in cost. I'm not against making my project easier, I just want it to last after all the work I will have put into it.

[tomherrick]

OK, ordered a couple of rolls of the Econoply E. Rather be safe than sorry. Thanks again for the help.

[redreuben]

The myth of not having to grind when using peel ply only applies to painted surfaces, if it is a structural bond you still must grind to expose fibre, otherwise you are just bonding to a layer of resin which is far from optimal for bond strength. IMHO.

[groper]

What myth? you CAN secondary bond without grinding (and save your health). You just have to use the right material and process;
http://www.tc.faa.gov/its/worldpac/techrpt/ar06-28.pdf

[CatBuilder]

Originally Posted by groper

What myth? you CAN secondary bond without grinding (and save your health). You just have to use the right material and process;
http://www.tc.faa.gov/its/worldpac/techrpt/ar06-28.pdf

That was a very good read. It is late and I'm tired, but I didn't see anywhere that they compared the bonding of sanding vs. the bonding of peel ply.

It's a shame they didn't, because it could put the whole thing to rest.

[redreuben]

Groper,
great read, thanks for the link, however the material they are dealing with is pre preg, hardly the material/process of choice for amateur boatbuilding.
I have seen joint failure in peel ply bonded engine beds and a bulkhead where the joint just fractured on the resin interface although it was VE not epoxy.
For structural bonds on wet layup laminates where resin content is higher I still believe a light grind to expose fibre is prudent.
RR

[groper]

Perhaps the failure occured because of a silicone treated peel ply ? What about duflex built boats, are these all falling apart at the seams ?

[CatBuilder]

Originally Posted by groper

Perhaps the failure occured because of a silicone treated peel ply ? What about duflex built boats, are these all falling apart at the seams ?

As an off shoot of the thread...

are those Duflex boats build just by slapping biax tape over a duflex panel? You don't even have to sand the Duflex first??

[groper]

no tape at all, just an epoxy glue join along the Z scarf edges, which laps the glass over the recessed edge on teh next sheet by about 20mm... its a secondary bond between glass layers (and core also) that have only had a peelply released surface to bond to... each duflex panel has peeply on both sides and you only remove it when ready to work with the panel so it protects the surface from contamination... and no they are not falling apart, i was just using it as an example of peelply bonds working just fine...

[benglish300]

Ive found that the new Compflex products are by far the most Superior product in vacuum bagging or V.I.P process. Peels off slicker than snot, leaves a decent tooth. It wont break the bank either.
http://www.fibertex.com/en-GB/busine...Compoflex.aspx

[CatBuilder]

Originally Posted by benglish300

Ive found that the new Compflex products are by far the most Superior product in vacuum bagging or V.I.P process. Peels off slicker than snot, leaves a decent tooth. It wont break the bank either.
http://www.fibertex.com/en-GB/busine...Compoflex.aspx

HOLY CRAP! Where do I get that stuff?!?


How do the flow rates compare to Airtech's Green Flow Media and Econoply E?