Peel ply....

[Roly]

Can anyone give me the low-down on peel ply.
The do's & do-nots!
I am using it over epoxy/glass in prep for overlaps,fairing compound,bilge paint,bulkhead tabbing.
Internal glassing;Hand laminating. I missed using it on the exterior hull glass---expensive time consuming mistake.

Tips Like price,best place to buy,how long to leave before pulling off etc.
Cheers.

[jonsailor]

There are many styles to buy and some are better for differant reasons.
You can buy a very coarse one which we use for flat panel bulkheads and tabing joins because it is easier to remain flat on the job without puckering.
We also use a fine cloth if we have to throw it over a large laminate or a contour one where we cannot pat it down smooth to wet out. This is only used in this sequence where we are vacumm bagging over the top. By using the fine one here, you avoid resin ridges than are more prominant from the coarse one if it is not laid flat.

We leave the peel ply on until we get to the final finishing stage as this keeps all the **** off the job until you need the final preparation. If we tab a bulkhead into a hull, we just remove the section around the hull for tabing so that the rest can remain clean of foot prints and resin spills. For instance, we will even paint the deck head first so the peel ply acts as a drop sheet for the rest of the yacht. Peel ply is the best thing since sliced bread and gives a good finish with minimal work for secondary bonding.

[Roly]

Awesome---thanks.
We just wore thru 3 valves, nipples & 8 ceramic nozzles trying to sand blast the shine off 40m^2 of hull. Inexperience on my part. Ended up costing shitloads more than peelply. Plus heaps of time and swear words.
Sounds brilliant way of keeping your work clean too.
Mandatory material I reckon. :idea:

[waikikin]

We'll often remove the selvedge from the peel ply as it usually lays a lot sweeter like that. Regards from Jeff.

[John ilett]

We use a peel ply commonly sold as a lining material in clothing. It's called polysheen and is typically much cheaper some peel plys sold by composite suppliers. It's only good for ambient cure resins and not for high temp such as pre pregs. Make sure your layup is slightly wet and quickly throw the peel ply on top and brush it down flat with a bannister brush (from a brush @ pan set) so that it will will moslty wet through from behind. This is easier and faster than trying to wet through the peel ply after. Having said that, apply more resin where needed with a roller rather than a brush.

Love that peel ply!

[catmando2]

Have looked at these post's and have to say I hate peel ply. I always seem to end up using excess resin like above post which = weight.

In the early 90s there were lot's of talk and some problems with peel ply having silicon or similar, making later bonds dodgy and I had witnessed a daggerboard smashed out of a cat with a nice clean fracture where peel ply was used.

I just wipe a thin bog slurry every where that needs paint or more work done while glass is green. At least then i'm not grinding glass for the next stage , have no contamination and dont spent a fortune on peel ply.

And Johns comment on the suit liner above is correct, we were using this 20 year's ago as well.

Dave

[nero]

I have found only limited functionality for peel ply in hand layup. I have a roll of perforated light weight peel ply that has a slightly green color. The only use I have found is as a release agent. I use it when pressing seams of overlapping glass on flat pannels.

The problem I have not over come, is the puckering and trapped air underneath it. All looks wonderfull until I remove the stuff and sand. Then a whole bunch of air bubles appear.

The other problem is that once the peel ply is on, I can no longer see dry spots or places where the glass has lifted from the core.

For secondary bonding and finishing, I have started to use an electric power sprayer and a sump pump. This does an excellent job of removing blush from the inside of the hull.

In areas that I am going to tab in a bulk head, I add a thick layer of resin just after the wet glass has gone tacky. From destruction testing, the results seem to be as strong as the origininal wood core/fiberglass bond.

[marshmat]

I'm not sure how much value peel plies would have in an open wet layup.
I have had very good success with Airtech plies in prepreg carbon and kevlar layups. They make release a lot easier, and leave this beautifully textured surface that epoxy just loves to weld itself to later on.
The same peel plies have also proven useful in vac-bagged wet layups. It is really important when using them to not use too much resin, though. The peel ply's job is to remove the waxes that float to the surface as the resin cures, and to leave enough of a texture, that secondary bonds will hold well. Too much resin in the layup, and the resin will soak right through the peel ply making it nearly impossible to remove. In open layups, covering the whole thing isn't going to accomplish much.
One option that often works is to lay strips of peel ply only where secondary bonds (ie. bulkheads) are going to go. This works fine in an open layup (no bag), it won't cut down on the weight but it will leave you with a good place to bond the next part.

[catmando2]

Are any of you guy's actualy doing destruction tests yourselve's , or are you just believing the sales rep?

Dave

[marshmat]

I generally do some testing of my own, plus building on the advice of previous team members.... don't take a sales rep's word for anything, sales types often seem to have little knowledge of the actual product, for info on that you need an engineer. But yes, in my experience with prepregs, peel ply is amazing stuff and results in much better secondary bonds than bare laminate does. Same goes for vac-bagged wet lay if you're smart with the layup. I haven't done much with peel ply on open wet layups so I can't speak to its effectiveness there, although with so much excess resin I doubt it'd be as effective.

[Pericles]

Has anyone experimented with stretching industrial strength wrapping film over the last coat of epoxy on a boat hull? Would it bond to the resin or would it pull off leaving a smooth high gloss finish without runs?

Pericles

[lewisboats]

http://duckworksmagazine.com/03/r/articles/glass/bottom.htm

Check it out...he uses .030 polyester to get this really nice finish...but it only works on something that can be got out of sheet materials.

Steve

[cookiesa]

Hmmm I like :)

I'm going to have a painted finish most likely... (easier to hide mistakes... my woodworking is not to a carpenters standard!)

Would I be right in thinking with this "gloss" finish a light sand for the paint to key in with maybe all that isrequired in the bulk of areas? (Thinking external parts of the hulls) Of course there is likely to be areas that need more work as I don't think I'd get close to that kind of finish on all the areas!

[rxcomposite]

http://duckworksmagazine.com/03/r/articles/glass/bottom.htm

Check it out...he uses .030 polyester to get this really nice finish...but it only works on something that can be got out of sheet materials.

Steve

Looks like a 0.003" thick plastic. A 0.030" is 30 mils and is thick as an illustration board.

[Pericles]

cookiesa,

Yes, light sanding is all that is necessary for painted finish. The film gives you the opportunity to miss much of the long boarding inherent in hand laid epoxy composite construction.

Cut the film to match panel shapes before pouring the epoxy, ensure correct wet out & bed the film per John Blazy's instructions. Do the work methodically in sections & allow each to cure before moving on, i.e. bottom one day, sides the next. Use masking tape will hold the film in place as necessary. Work smart, not hard. Google Polyethylene Terephthalate, often referred to as PET film but commonly known as Polyester PET.

P

[cookiesa]

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

[latman]

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.

[Herman]

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.

----
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
----
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.

[latman]

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.

[rxcomposite]

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.

[rwatson]

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

.

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 ?

[Herman]

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?

[rwatson]

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.

[Herman]

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.

[michael pierzga]

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

[PAR]

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.

[Herman]

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.

[themanshed]

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

[tunnels]

Can anyone give me the low-down on peel ply.
The do's & do-nots!
I am using it over epoxy/glass in prep for overlaps,fairing compound,bilge paint,bulkhead tabbing.
Internal glassing;Hand laminating. I missed using it on the exterior hull glass---expensive time consuming mistake.

Tips Like price,best place to buy,how long to leave before pulling off etc.
Cheers.

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 !!.
:D

[masalai]

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

[rxcomposite]

Don’t throw it away send it to me the stuff is not cheap!

One of our guys would always salvage the used peel ply. He says that when it is laundered, it makes for a good sail for his small sailboat. For the still smaller pieces, he sews them together. What a great way to recycle.

[Yellowjacket]

Does anybody know a source for polyester film to use for covering laminating.

The only stuff I've found thus far is a 4 x 8 sheet of.030 inch material. I haven't been able to find a roll product and I would prefer a narrower width. The cost of 4x8 sheet was reasonable (about $35), but for what I'm doing a narrower sheet on a roll would work better for me.

[rwatson]

Does anybody know a source for polyester film to use for covering laminating.

The only stuff I've found thus far is a 4 x 8 sheet of.030 inch material. I haven't been able to find a roll product and I would prefer a narrower width. The cost of 4x8 sheet was reasonable (about $35), but for what I'm doing a narrower sheet on a roll would work better for me.

I cant see what area of the world you are in - but look for the trade name Mylar, that seems to be pretty common in most parts of the civilised world. It comes in rolls.

[lewisboats]

I have used Clear Vinyl very successfully...you can get it a any decent fabric store or online by the yard. Here is an example.

http://www.onlinefabricstore.net/specialty-stores/upholstery-vinyl-store/vinyl-projects/marine-vinyl-fabric/clear-marine-grade-vinyl.htm?pds=3

[themanshed]

I've also used 3M painting plastic. Make sure the 3M emblem side is down towards the wet work, if backwards it will stick. Test a small piece to get use to the method. When working with foam and epoxy I mix a little bog with the epoxy to get the foam pores filled by brushing on the mixture before my first lay-up. Then do a regular layup. I use an auto body type plastic squeegee; the plastic is thin and works out well the squeegee action will remove the excess epoxy by working it to edge. Once it is dry the 3m plastic comes right up. Make sure you leave some extra 3M painters plastic overlap that stays dry on the edge to use to pull it off, easier to grab no chance of glue over. A roll can be purchased at most paint or home project stores like Home Depot and it is cheap. This method gives the effect of both vacuum bagging and peel ply.
The picture below I was puting a two layer lay-up of 200 gram carbon on foam for my bulkheads.

Just a note I only use peel ply (costly) when doing a vacuum bag job so the excess can bleed though to the bleeder cloth all other times I use the above method and I'm still on my first roll of cheap 3M painters plastic.

[Charly]

Hi the manshead,
That stuff is only about 4mil thick isn't it? And the the vinyl stuff is about 30 mil thick? It sounds like the thicker stuff might make a fairer surface on a large area, like a hulls exterior. Does the thickness make a big difference? I am curious because I hope to be coating and fairing my two 36 foot hulls is a few months. They get one layer of 10 oz cloth over okume ply. I have been assuming that I would fair it, lay-up the cloth, coat it again while tacky and then peel ply, hopefully then to have very little sand prep before priming. Now I am thinking maybe to go with the vinyl instead of peel ply and just wet sand the whole thing before priming. What do you guys recommend?

[Yellowjacket]

The best thing I have found so far is PTEG sheet. At $32 per 4x8 sheet it's going to cost about $130 to do what I have to do. Not too bad, but not cheap for a throw away piece of plastic.

Most of the Mylar I've found is pretty pricey. To buy enough Mylar to cover the hull I am doing is going to cost almost as much, or more, than the epoxy that I will use. It's looking more like $200 or more to do the boat I need to do. For a pair of 36 foot cat hulls you are talking at least a thousand bucks for that much sheet, so if the vinyl works for that it could save a bundle.

The mylar I've found is limited to mostly .014 thickness. The guys using it for RC airplanes have found .014 mylar to work pretty well, but they are using pretty light cloth. If I have to go with Mylar I'm thinking that .014 is a minimum thickness that will work well.

Lewis boats, What thickness of the vinyl did you use?

I had seen that marine vinyl at Online Fabrics, and wasn't sure if it would work all that well. The vinyl is a lot more flexible than an equivalent Mylar sheet. More chance to get wavy surface and uneven amounts of resin under the sheet. The price is right though. The boat I am doing is made up of relatively flat sheets so the stiffer material for me the better it is likely to work.

[lewisboats]

I am not sure exactly what the thickness I used...I bought it at Walmart in the fabric department and it didn't really say except that it was the "thickest". I expect it was 15 or 20 mil judging by the roll plastic I use at work which is 4 mil.

[themanshed]

Charly,
The hulls should be fare before fiber glassing. So what you are trying to do it is to get the lay-up on as smooth as you can. The 3M painter’s plastic is thin and light you can work the material - epoxy and lay-up really well and see your work as you go. Plus the 3M painter’s film does not mind shaping some to your piece or surface. A little epoxy on the squeegee edge as a lubricant works good and lets you glide along. The finished parts come out very smooth. A little scuffing and you are ready for the Yacht finish.

I've not used the thicker plastic, Mylar, or vinyl. Those materials always seem to want to fight you when you use them as indented. They kind of have a predetermined shape that they like to keep - flat - and wrinkle or bulge when they meet a curve. Plus all the weight you are talking about as the length gets longer not sure how that matches up with epoxy and fiberglass.

Peel ply is ok but you do not see your work and the parts come out with a matted surface. Peel ply is great if you want to do more lay-up, but the hulls still would need more work to put a shine on it. The cost is way too much. The only problem I have is that I need it for the bleed through for vacuum bagging if it was not for that I’d not use peel ply.

For the minimum cost of a small roll of the 3M you should try it on a small panel for a test. This method makes a very compressed lay-up that you would think was vacuum bagged. I read about this method as an alternative to vacuum bagging several years ago in some reference material. Anyway it is neat trick I like and use, and if you do not like it when you paint your house you can always finish up the roll of 3M painters plastic. As always take several ideas test them out and find out what works best for you, your build, and your wallet.

[Charly]

Thanks guys.

I will do a few experiments before I commit to the hulls. I used some six mill poly over a rather large hull patch a few months back. It worked OK, but the end result was uneven resin (Wavy) thickness. Maybe I didn't squeege enough resin out of the cloth after I put the plastic on. There was also a problem getting it smooth where there was a crease in the plastic, as it comes folded up on the roll.

[Yellowjacket]

I'm going to do the heavy fim trick on my boat. I've found the .030" PTEG (trade name Vivak) sheet for a very reasonable price at a local plastics shop. Meyer plastics has it for $26/sheet. I shouda looked locally before I spent hours on the web looking for the best price.

I'm doing a plywood sheet hull with it and was curious if Par could chime in since he has done the plastic sheet trick process previously (and obviously knows his way around the epoxy patch). I'm planning on using a fairly thin resin (600 cp Raka) for wetting out the cloth since I want to wet out the glass well for a clear finish (and also Raka 350 is realllllllyyyyyy sloooooooow which is what I need).

The question is, when using the thick plastic process, is it better to use a thicker more viscous resin or will the thin resin work just as well. I'm thinking that the thinner resin will wet out the cloth better, but have a concern that the thinner resin would mush down the cloth more and won't leave as much resin on top of the cloth. I guess I can go back and put another coat of just pure resin on the top after I take off the plastic, but that kinda defeats the process to some extent.

Also, Par, when you are doing this do you squeege as much out of it as possible or do you leave it a little bit wetter and just roll the excess out from under the plastic???

[rwatson]

If you are putting mylar over the top, it doesnt matter as to the epoxy thickness, as it will just hold it all in place, even on a verticle surface.

Is you hull made of developable surfaces only ?

If it isnt, the thick plastic will cause big blobs where it cant lie against the fibreglass cloth.

I suggest you do a couple of small test panels first to make sure the stuff will peel off later, and get the feel for the epoxy you are using.

[Yellowjacket]

The boat is all developed plywood surfaces. It is a classic racing runabout from the late 70's. The mylar will have to be pieced, but this application is exactly what the process was designed for. There won't be any issues with bunching or blobbing, but the middle of the bottom the hull is done in two strips that that are a foot wide (13 ft long), and two subsequent on each side that are about 8 inches wide and eight and 10 ft long. Since I'm doing relatively long strips I want a slow epoxy so that it isn't setting up one end by the time I get back to the end where I started and start the next srip.

I plan on doing some interior surfaces first, but wanted to know if you squeeged it out to be relatively "dry" and then put the mylar on, or if you left it relatively "wet" and rolled out the excess epoxy with the mylar on it. In describing the process some have said it actually uses less epoxy because when you roll out the mylar it compresses the cloth (somewhat like a vac bag, but not as much pressure).

[rwatson]

Sounds like you are on the right track.

The Mylar will compress slightly, but no more than a good squeegee job would, as the fibreglass cloth is un-compressible. The air pressure against what is virtually a vacuum makes helps a lot. The trick is to do a slightly sloppy job of squeegeeing the goo onto the cloth at first, so you have little bits of excess at intervals.

Apply the mylar from a roll, (roll it around a hollow pipe, which is suspended by a rope through the pipe, that you can move along the hull) starting at one end, and use a hand roller and/or dry squeegee to smooth it down as you go.

You will find as you hit a dry spot, that you can often 'roll' some excess goo from an adjoining area into the dry spot, or worst case, back off the Mylar by about 6 inches, and put a bit more goo on the problem area. (Be careful not to lift or wrinkle the cloth as you do.)

The trickiest bit is to make sure you have aligned the Mylar roll with the hull panel before you start. You can get a third of a way along the hull and see that the mylar edge is too high or too low, and you are going to end up with 6 inches or so uncovered at the other end. If that happens, dont try and re-lay it, just cut out some more mylar into a triangle and cover the exposed bit.

Don't expect to get a finish that will require no sanding entirely, but it will reduce the amount of sanding hugely. Often the Mylar will have a 'bump' in it made by folding, or a production fault, that will make a slightly thicker bit of epoxy than required. Or, you may find a bit of the hull that has a 'dent' or a rise. These are easily straightened later with a long fairing board.

Don't be scared of scuffing up the surface with 'sandpaper' after you have removed the mylar. If you use 'wet and dry' quality fine paper, say 120 grit to finish, the protective coating will restore that deep lustre with no problems.

[Yellowjacket]

rWatson, Thanks, that's the kind of advice I was looking for.

The hull is 13 ft long and has a 56 inch beam, and the bottom has to be done in one coat with no stops. The hull is very well defined in that each section of the bottom is one strip of plywood that isn't twisted very much and it will be pretty straightforward to make the mylar to fit. Thanks for the overhead roll trick, I will definitely do that for the wide center section. The other sections are pretty narrow, only six and eight inches respectively, so I can just roll it up and handle those narrow strips.

I'm don't think I can wet it all out and then put down the mylar before is starts to gell, so my plan is to work in strips. This is one reason I bought slow epoxy.

The current plan is to start in the middle, work from transom to bow in a two foot strip, leaving a couple of inches wet past where the mylar will be, and put down the center strip of mylar. Then do a single 6 inch side strip on each side (which should go pretty quickly), and then follow that with a final 8 inch wide strip on each side.

One other approach is to work from one side, the epoxy doesn't have time to start to set up along the next edge before I get there. Probably have to be careful with how the cloth pulls over the bow edge as I work it but I won't have a problem with the epoxy setting up before I get to the next part. Also it might be easier to keep the mylar aligned with the one edge as I go along. I'm thinking I could probaby keep each section of mylar lined up with the previous section and avoid (but not totally eliminate) a lot of recutting and fitting the mylar.

Any thoughs you have on the approach are most welcome. Perhaps I'm over analyzing it, but I only get one shot at this without making a mess of it and it's a lot cheaper and easier to carefully plan what you are going to do and then do it as opposed to trying to figure it out on the fly.

[Charly]

Good luck Yellowjacket!

hope you are able to post some pics

[skyking1]

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.
Par, I have not found the 10 mil stuff on a roll, could you give me a product name to search for? 10 mil sounds perfect.
I will be trying this out on my next layup.

[Pylasteki]

Does the mylar/polyester sheet work on thicker cloths like 12 and 17 ounce biax, or is it only good for 6 and 10 ounce woven cloth?

Thanks

[Yellowjacket]

If you are using in on final layers of anything it will be better than not using it. The heavier the cloth, the more it tends to "stand up" when wetted out. the plastic seems to result in a more "compressed" layup that uses less resin.

On heavy intermediate layers I don't know if it is better or not, I haven't used it for that.

[rwatson]

yes - thats right.

basically, it will 'flatten' any size weave, but with the thicker weaves you are going to have a lot more resin used just to level out the surface.

Unless you need a flat mirror finish, peeply produces a less resin heavy finish, but not as flat or shiny.

Also, if your Mylar has been wrinkled, putting a heavy flat object over it will reduce the sanding needed, caused by the resin standing up under he wrinkles.

I wonder if you can successfully iron out wrinkles in Mylar like peelply?