speak to me of " peel ply"

[soundman]

I hear about this peel ply.

Whats the story, how does it work and what are the traps.

cheers

[Boatmik]

Howdy Soundman,

There be some traps. A couple of times people who have used it on this forum have recommended it to someone else with a "no worries" type attitude.

However the chap/s who have taken that advice have got into strife.

I haven't used it enough to be able to advise - but there are some advantages - but all the advantages are lost if it is used incorrectly with voids resulting in some places (you end up with big sharp edged hollows that take a lot of filling or lines of built up resin where there are creases.

But if it goes well it can save heaps of labour as the result is a clean surface requiring a minimum of labour to get ready for the next coat.

I would be interested to hear some specific advice and some do's and don'ts too

Best wishes
MIK

[bitingmidge]

I am very wary of it in a conventional layup. As Mik says, if it goes well, all well and good, it may save some work.

If it doesn't it WILL create work!

If you are vacuum bagging, and it's a great way of controlling the resin quantity and you'd be mad not to use it, but without bagging, if you use too much resin, and you pretty much have to to cover the peel ply, there's a risk of "floating" it off the surface.

I would prefer to use as little resin as possible in the laminating stage, and then a couple of filler coats if necessary, (at least one will be) sanded between.

Cheers,

P

[b.o.a.t.]

G'day Soundman

Peel-ply looks & feels like a super-fine weave nylon shower curtain. It works by acting as a second "surface" on the top side of your lay-up. If you use just -exactly- the right amount of epoxy evenly coated across your lay-up, the peel-ply will flatten the high spots over the crossovers in the glass weave into the low spots between the strands, allowing air to escape through its own very fine weave. This "pulls" it down onto the job & may make the total thickness of your epoxy/glass sheath thinner & lighter. Once your lay-up is dry, you simply peel it off leaving a flat surface with a super-fine weave texture to it that needs very little attention before recoating. A little excess epoxy may also wick through the peel-ply & that will be removed when you peel it, along with any amine blush. A big saving in time, effort & sacrificial epoxy.

At least, that seems to be the theory...

As MIK & BitingMidge have stated, peel-ply has its traps. I've used it just the once & liked it. It would be fairest perhaps to say that it creates a different set of problems which you may find easier or harder to work around.

As a result of its use, I had areas with slightly insufficient epoxy leading to whole areas with pin-holes between the glass weave. These needed careful filling. Wherever the were two pieces overlapped, or there was too much resin, there was a ridge and/or dip needed filling/sanding. Also, it is a right mongrel of a thing to apply smoothly & squarely over a 3-dimensional surface.

Despite this, overall it made sheathing my kayak easier ***for me***.

I didn't have the regularly spaced blocks of time to do wet-on-wet recoating & building of epoxy thickness. So I would have either needed to delay progress a month or three until I had the time, or do 3 or four full sandings to ensure adhesion between epoxy "build" coats. Peel ply enabled me to sheath to near full epoxy depth in a single big block, then pick away at the imperfections over the next few weeks as time allowed, with a final build coat much later and a single big sanding. By my reckoning, it saved me about 20-30% epoxy usage & an awful lot of sanding - the first one or two rounds of which would have cut into my glass cloth, compromising its integrity.

Where I have had suitably spaced time blocks, such as when repairing a seam on another boat last month, the easier course was wet-on-wet build & a single sand & fair. Might have used a little more epoxy, but one less piece of unco-operative cloth to wrestle with!

Hope this makes sense...

cheers

[Lewy the Fly]

Ther is definatley an art to using peel ply, firstly an extra pair of hands is a great help, secondly ther is generally two grades, I find the heavier one the easiest to use, its less likley to float as mentioned above. I find it best to get a nice even, not too thick coat of resin on then apply the peel ply the quicker the better then sqeegy it out and apply extra resin over the top to any dry or air trapped areas. I found that laminate peices work great as sqeegy's. Frankly I think its the best thing since sliced bread and wouldnt work with out it.


Regards

Lewy

[soundman]

Hmm .......I think I am standing under.......( does punjabi head wiggle).

not just yet for this indian then.

cheers

[Lewy the Fly]

Chicken! Have a go

The greater danger for most of us is not that our aim is too high and we miss it, but that our aim is too low and we reach it.

Regards

Lewy

[cookiesa]

Whilst epoxy coating the insode of a dingy on saturday (with the preservative additive) I noticed how much nicer the epoxy was to work with (much thinner, easier flowing). Now of course it would use a little more resin as it "penetrates" the marine ply better but it did get me thinking how much easier it would be to apply the woven mat using the dry method with the thinner resin. I was also thinking you could perhaps get a lighter coat a little easier as the thinner resin will run in to the weave more so than the thicker resin.

Has anyone tried this? I could see that the fact it soaks in means you would need to be carefull to make sure the cloth is wetted out properly

[PAR]

Peel ply is costly and completely unnecessary. Stop by the local fabric store. You know the one your wife goes to get material for new drapes, etc. Then pick up some, plan old "rip stop" nylon. It's a lot cheaper then peel ply, works just as well if not better, because it conforms easier and you don't feel bad if you cut it up or ruin some.

The use of these "surfacing fabrics" can save some work, though (except for vacuum bagging or resin infusion methods) I question how much effort you save.

With a surfacing film, you can avoid amine blush, because the free glycol groups can't react openly with the moisture in the air, so you get a blush free surface. It also provides a "toothed" surface once peeled off, that can be bonded directly over (a questionable tactic in highly loaded, secondary bonds). To some this saves time.

In my way of doing things, previously coated surfaces receive enough dust, grime and other contaminates, that I have to clean and abate the surfaces anyway, just to be sure a mechanical bond will be successful. If you're doing multiple layups with "green" epoxy, in a clean shop, then peel ply can work. On the other hand, if your shop is like mine, with dust floating around like fish in the sea, then any surface that has reasonable exposure to the open air, should be wiped down at least (dry, but green bond) or both wiped and sanded (secondary bond).

I've not had failures in either style of bond, but I'm pretty procedure oriented with epoxy efforts. I've seen plenty of failures, and most (other then mixture screw ups) can be traced back to bad surface prep. If you have to prep the surface, then peel ply seems to me a waste of time, at least to me.

[cookiesa]

Could the peel ply be beneficial in a "dusty" type environment for perhaps helping to keep bugs and bits off the drying epoxy?

(Or am I misunderstanding how long the peel ply is left in place?)

[b.o.a.t.]

Could the peel ply be beneficial in a "dusty" type environment for perhaps helping to keep bugs and bits off the drying epoxy?

(Or am I misunderstanding how long the peel ply is left in place?)

Yes.
But consider the above caveats about other problems peel ply may substitute...
There is also the point that you will need to coat the cured epoxy with some sort of
UV protection - paint / varnish / bitumen / etc. Peel ply will not help you keep dust
etc off this. If that's all you are using it for, might be better to fix the dust instead.
You will need to do so for top-coating anyway.
cheers
AJ

[cookiesa]

Thankfully I don't have that problem.. more just a thought/query

[Boatmik]

Could the peel ply be beneficial in a "dusty" type environment for perhaps helping to keep bugs and bits off the drying epoxy?

(Or am I misunderstanding how long the peel ply is left in place?)

No Peel Ply comes off. Generally though you have to sand the epoxy for the next coat of varnish or paint anyhow so dust is not a problem.

Peel ply CAN reduce the sanding, but if you don't get it right it can lead to some deep sanding and filling to get rid of craters where there were air bubbles under the peel ply.

I would generally suggest that people try it with a number of small projects rather than use it straight up on a 40 foot hull!

MIK

[cookiesa]

Overall sounds like it is probably more trouble than it is worth for anyone who isn't using the technique and perfecting it on a daily basis.

[graemet]

I used peel ply on my 18 footer and found it was great for ensuring that I didn't have too much resin in places (it all comes through the ply) and when I peeled it off after the epoxy cured, any runs came off too leaving a much smoother surface to sand and it took all the amine blush with it as well.
Perhaps I was lucky but I feel it was money well spent.
Cheers
Graeme