Peel ply....

Thanks for the info. Definately will be investiagting it. Back to cutting out the bulkheads!

 

We use the beige polysheen (cheap /fine weave) on dry glass , then bag and infuse with VE resin , I would never trust secondary bonds directly against the peel ply surface and we always sandpaper the area , the peel ply does give a nicer flatter area to sand compared to the resin lines you get from bag wrinkles. The fine stuff is not too strong so if the finished laminate is going to be left overnight or longer i also put some red perforated film down in any concaved areas so the spiral tube (resin feeder) can be removed easier.

 

I did some testing with secondary bonding: An epoxy laminate over a VE laminate.

We tested the following options:

-no prep at all, except for acetone wipe
-sprinkled sand into the VE
-sprinkled short glass in the VE
-sand with grit 60, acetone wipe
-peelply


Then we infused a laminate over all test patches.

After cure I took a chisel, and pried the laminates apart.

All laminates came apart, except for the peelply one.

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Keep in mind that there is a lot of different peelplies. Take a look on the Airtech website: 28 different styles... http://catalogue.airtech.lu/category.php?category_id=6&lang=EN
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I see someone is confusing perforated film with peelply. These are NOT the same and usually are used together in a vacuum bagged laminate, or an infused laminate.

 

I actually knocked a gelled but not completely cured Secondary bond some time ago and it just fell off. so its sanded for me....

ps beige ,black ,pink or whatever colour for peelply is fine for us as long as its not black (same as carbon) or white (goes clear when wet out) I know one of my suppliers sells heavyweight white with a red stripe in it.

 

Green seems to be the favorite color but those who order white prefer the stripes (or tracer) so it can easily be seen.

I remember also that there was a study made between sanding and peel ply and sanding came out the winner. Weli, we use peel ply to have a smooth surface but still sand, lightly that is. Heavy sanding would cut thru the fibers and that is trouble for the QC/QA.

 

Just to clarify Herman - I seem to recall that West dont recommend any type of solvent as a cleaner prior to paint or recoat.

Have you tried those tests with sanding but no other cleaning agent except water ?

 

No, we didn;t. And as that project is past now, it is unlikely that I will find the time to do another test.

Peelply did the trick with this project.

Did West give reasons why?

 

I will go and check, but as I recall the problems was spreading thinned 'impurities' over the whole surface. As I vaguely recall from other discussions in these forums, Acetone itself can be manufactured with impurities that prevent good bonding as well.

I will have to re-research the topic to reboot my aging memory.

Good suggestions here
"4. After you are satisfied with the texture and fairness of the surface, rinse the surface with fresh water. Rinse water should sheet evenly without beading or fisheyeing. If rinse water beads up (a sign of contamination), wipe the area with solvent and dry with a paper towel, then wet sand again until beading is eliminated."
http://www.westsystem.com.au/west_system/basic_techniques/final_surface_preparation"

West make a special solvent for epoxy cleanup, but they seem to be generally happy with Acetone as part of the process.

The trick seems to be to make sure that water is the final thing to touch the surface.

 

On Aceton:

There are several grades, including "chemically pure", which is what you should buy.

On wiping:
I think at least 90% of the people make a mess of solvent wipes. The whole point is that you dissolve "impurities", but as the acetone evaporates, the impurities still stay behind, just spread out.

The only proper way of doing a solvent wipe is to soak the surface with solvent, then immediately dry with a clean cloth, and repeat this 3 times. (with clean cloths, change them often)

For regular degreasing I like to use water and ammonia, as this does not evaporate, and is so cheap and non-hazardous, that you can really rinse.

Also the West solvent has the evaporation problem. Proper workmanship is required.

 

Solvent wipe is prone to contamination problems. I never observe Pros use a solvent wipe...

As Herman stated WATER Ammonia , a soft scrubbing brush or 3m pad, rinse, wet dry vac, air dry.

One of the beauties of Peel Ply is that if you are working horizontal surfaces, high traffic areas...bilges...the peel ply keeps the contamination off the substrate.

Always use peel ply....dont touch exposed surfaces with ungloves hands, constantly vacume work areas and keep work areas clean.

This is craftsmanship

 

Most pros don't use peel ply, but instead nylon or polyester fabrics, typically "rip stop". It can be had "virgin" which solves the "finishing" contaminates that can be found on these fabrics, if you don't want to learn this the hard way.

I use the heavy film trick mentioned on the previous page. Mylar and polyester sheet goods. I get it on a roll from 10 to 30 mils and it's a fairing dream, especially with bright finishes. It leaves no tooth and doesn't breath like fabrics do, no contaminates, no bugs. Of course these heavy materials need to be diagonally arranged on round bilge boats, but plywood boats you can go with the planking flow. Most use peel ply thinking it'll save them a bunch of time, but their shop conditions require that the surface must be cleaned and sanded anyway, in spite of the peel ply. Ridges left by butt joints on the rigid plastics (diagonal stripped round bilge projects) are easily knocked off with a scraper or DA. If your shop is clean and environmentally controlled, then peel ply is a time saver, other wise, not so much.

 

Most pros use peelply. When bought in larger quantities, it has the same price as rip-stop, but is backed up by a supplier that takes his responsibility when something is wrong. No need to gamble with Indian untested fabrics, which mostly are "loomstate" so can include contaminants.

 

Peel Ply is what it's name say it is to peel off. I use it when doing vacuum bagging. The peel ply goes over the outer surface of your upper most layer of laminate. Then on top of the peel ply a bleeder cloth. Some people will put a thin layer of plastic 2-3 mills with many close holes in between the peel ply and bleeder cloth to keep the bleeder cloth and peel ply from sticking together. Then your vacuum bag goes over top of everything and gets sealed with the vacuum hose leading out of the bag. When the air is sucked out every gets compressed down to the laminate forcing the extra resin / epoxy through the peel ply into the bleeder cloth when the excess is collected and feed though the vacuum hose to an overflow tank if too wet. So the peel ply servers two purposes to release from the laminate and allow your resin / epoxy to flow through the weave. Most peel ply has a no stick finish to it. Sometime it is like skinning a gorilla to get the peel ply and bleeder cloth off after the resin / epoxy has catalyzed. Don’t throw it away send it to me the stuff is not cheap!

Here is a little on vacuum bagging: http://themanshed.net/tms-20-trimara...ull/?g2_page=2

 

Peel ply is really good to use , It helps to compress the layers of glass and the surplus resin comes up through and when the peel ply is eventually ripped off takes the resin with it . LEAVING A 100% CLEAN virgin surface to do what ever you have to do . Paint , bond , add glass to etc etc
When to rip off ? dont be in a hurry!
Its a way of keeping the surface perfectly clean so drops of resin paint drops glue mark , dirty foot prints you name it when you pull the peel ply off ll those thins go with it straight into the bin !.
Can stay there for months of even years and does not need to be pulled off as soon as its hard . All the racing yachts are totally covered with peel ply inside the hull , deck ,bulk heads stringers you name it it has peel ply. same when tabing in Bulk heads etc etcThe tabbing is peel plyed as well .The very nature makes it easy to see the condition of the panel when it is finished , No humps bumps or un even rolling no roller marks so very little fairing and filling is reqiured . The more you use it the more you will want to use it !Its great when doing repair work on the outside because it shows the shape of the surface perfectly !!!.
Just remember to peel it off and dont glass over it ever !!.

 

Peel ply is Polyester Taffeta and is sold by fabric wholesale outlets, (get friendly with the fabric supplies traveller who visits your area), in 50m rolls that are 54inches wide - seconds can be got readily for about AU$1 per metre or less... it retails at $6/metre from the dress/curtain material shops... ATL also sell it in narrow widths appropriate for tapeing...

http://www.atlcomposites.com.au/atl_composites/dealers/australia

http://www.atlcomposites.com.au/atl_composites/epoxy_products/west_system_brand/technical here are some useful pdf files on various topics