I must admit that I have never even seen the word 'coracle' and had to look it up.  They look like a bowl.  If I tried to use one of those, it would need pontoons around it!

This should be extremely interesting.  I hope you let us know how you're getting along with it, with photos.

If you do use shellac, be sure to use the real shellac, not the synthetic kind.  And shellac needs recoating every year or two, as it wears away.

Good luck!

Sue

Hey, this is really interesting.  As Sue (Catperson) says, we will be delighted if you reach a point of being able to share pictures with us all.
Why 'good quality paper'?  It sounds as though you mean expensive stuff.  I find that alternating layers of kraft (brown packaging) and bond (office type) with PVA produces a very strong laminate, at no cost.  Of course it has to be waterproof so in this case you probably won't use SCMC or wallpaper paste at all.   I'm sure you'll try some experiments first.
Stress points?  You mean where it is most likely to collapse?  Well, anywhere really but the weakest area would be around the rim where it would have to be very strong to withstand pressure without collapsing inward.  I would have thought that an internal frame, such as you would use with birchbark etc.  could only be helpful.  The Welsh coracles are a good example, where the outer skin is only strong enough to withstand the water pressure.  The rest is done by the frame.  I haven't looked at the other coracles you mention, but am just about to.   You can make strong frame structures with heavy duty card shaped into squared or triangular tubes but this would be very vulnerable to water ingress.
DavidO

Well I was going to proceed by creating a mould -- a mound of bagged sand sculptured to shape, covered in cling wrap, and laying the  pasted paper on top of this. The shape would be an upside down bowl, you see -- very straightforward. This was how I've done masks, either with clay, paperclay and other mixes as a mould and if necessary you just pulled the framing material apart to retrieve the shaped item once it dried

With that approach any frame-ing would have to be added later, you see. 

So imagine I then have this very large bowl made out of <i>papier mache.</i> I then upturn it so that the lip faces up, and then begin to lay down "structure" inside the bowl itself, adding several more layers to the rim, and creating a fan effect frame inside the bowl by laying down bamboo skewers, strapped end to end and adhering them to the 'hull' with further layers of paper -- ie just like a paper fan in fact with bamboo ribs. The only alternative I can imagine to this would be to lay down narrow  strips of several layers of paper.

I had this coracle construction process in mind
http://koti.kapsi.fi/hvartial/coracle/coracle.htm
which uses meshed plywood strips for the frame.

I've actually done experiments before with aluminum foil  and found it very resistive to glues but I also don't understand your suggested usage.

On the question of the glues -- I've used PVA and find that since it is plastic it  can often whell up and coagulate between layers whereas cellulose glues are much easier to 'merge' with the paper being, essentially, the same material -- plant pulp. What I mean is that I really lay on a lot of hand pressure when I'm laying down paper layers and treat the form and its paper as clay.

I used to make masks by creating a paperclay slip and cellulose glue mix soaking felt cloth in this then working the felt over a face (mask) mould so that any fold in the felt merged with the material as though it was all pulp. Once I had the profile just so I'd then coat it with a PVA/water mix -- thus plasticating it and laying down a undercoat. I'd then often use boot polishes on the masks or melted crayon wax. You get some exciting effects.

I'm approaching the coracle from the same angle  as I look upon paper or felt as very malleable stuff that can be 'panel beaten' with hands on pressure. Because of its ease of use, I preferred felt for making masks (so long as it hand some natural fibres in it as not all commercial felt has and pure wool felt is far too dear) , especially with the PVA coating and boot polish as they were always lighter and more flexible than papier mache. In fact if you can imagine how wool felt is turned into items-- hats, bags, etc -- you get an idea of the approach. In the same sense of, I guess, using paper pulp in mould and heating it without glues as one guy I know made his masks.

One approach I thought of was in fact to build any frame out of paper pulp rather than strips of paper....as pulp, in my experience (for better or worse nautically) is stiffer and more brittle than layered paper strips. But glued pulp is so fiddly and hard to work with.

As for waterproofing -- as far as I'm concerned -- any saturation is a problem. The paper boat literature errs towards cellulose glues  primarily because there is less chance that the layers will lift from one another and offer channels for water seepage. But no glue is going to replace the protection offered by a good coating and as literature suggests, moisture will eventually find it's way through even an unbroken layer of paint or other surface coating.
http://kcupery.home.isp-direct.com/PBAr … kslaw.html
So that's the key issue -- what you coat with and, I suspect, how often you coat. And most important sand down the hull to baby bottom smoothness.

Since I'm seabound in this I don't want to drown although I'm only planning to muck about in shallow waters -- inlets, tidal marshes, and creeks -- close to shore but maybe within cooee of an occasional bull shark.(And here really big sharks are known to bite surfboards in two!) However, the main thing to note is that these craft sit on the water, not in it so the pressures are spread evenly as a snow shoe distributes the wearer's weight on snow.

I can not resist offering a few words of advice on paper boats. (http://kcupery.home.isp-direct.com) is my site and I've spent a number of years on paper boat research... but mostly historical. (Paper mache I'm not so good at and confess ignorance of things you folks do).

Anyway, I was recently in a library that has a sample of the paper from the canoe that Nathaniel Bishop used in his  "Voyage of the Paper Canoe", (referenced in the first post). It is clearly as it has been described; a very thick single sheet of linen paper (several mm thick) that has been saturated with a resin of some sort. My guess is shellac, although I was not able to do a chemical test on it (yet).

Secondary literature suggests that the Waters & Sons firm used shellac as part of their "proprietary waterproofing process". They never provided details. I'm guessing it was a mixture of applications of shellac and varnishes or oils (think linseed oil).

Literature also suggests that they used shellac as a glue when making rowing shells out of multiple layers of manila paper.

As for modern canoes of paper, I've seen several that were in sad condition rather quickly. One in particular looked elegant when new, but quickly (one week-end with some rain) became "lumpy". The sad person who had made it used carpenters clue for the paper and a latex paint on the outside. Both are bad news with respect to water.

For amusement some folks build canoes using newspapers and wallpaper paste. They often get a lot of attention, (particularly if you use the local newspaper), but they are indeed temporary boats at best, regardless of how you paint them.

The canoe I built has been surprisingly durable, but I resorted to a marine epoxy resin as a coating inside and out. (I used a Weldwood Plastic Resin to build up paper layers, but that is simply water resistant, not waterproof.) This is sort of cheating I suppose, but I was never really striving for an historical reproduction. More details at: http://kcupery.home.isp-direct.com/PBArtic/TandC.html

Last edited by kcupery (2009-12-14 18:48:19)

Keeping in mind that I know nothing about these things... but I would like to toss a few ideas out there...

"It is clearly as it has been described; a very thick single sheet of linen paper (several mm thick) that has been saturated with a resin of some sort. My guess is shellac..."

Perhaps it is my interpretation, but it almost sounds like the linen paper was formed into paper a thick, single sheet expressly for this project.  Could it have been made right from the fibers into a single sheet, rather than laminated or multiple sheets?  It seems that a piece of paper like that would be far stronger, and not subject to the stresses of multiple layers that might have flaws in the lamination that would create weak areas.

Are you dedicated to the idea of a PAPER coracle?  Fabric would be stronger, even laminated fabric.  Imagine a laminate formed from several sheets of (well-laundered) fabric, with shellac used as the adhesive?  And the original, being made from linen fibers, was really closer to being a fabric than a paper.  Our American 'paper' money is really 100% cotton fiber, there is no actual 'paper' (wood fiber) in it.  As with Bishop's paper canoe, I suspect that the term 'paper' had more to do with the process used to make it than the materials used.  For instance, linen and cotton fiber, formed into woven sheets is called 'fabric', but linen and cotton fibers just melded together is called 'paper'.  Linen and cotton fibers are far, far stronger than the poor grade of paper produced today as kraft paper or anything similar.

Wouldn't using a non-waterproof adhesive be begging for problems?  One slight abrasion of the coating, and I would think the moisture would move laterally through the skin.

When boatmakers use fiberglass and resin, they are impregnating the fiber with the resin, not just adding it on the surface.

And I think David is correct in that the rim is your weakest point, as it will tend to flex as the weight (you) in the coracle shifts.  And it would seem that the rim would flex more without a frame than with one.  I cannot visualize anything stronger for the purpose than bamboo that would still blend with your adhesive/coatings. 

I suspect that plastics of any kind would be out of the question, either as adhesives (PVAs) or framing.  The disparity between the materials would probably be too great, esp with the adhesives.  I doubt that you will find a single adhesive that will stick well to paper (or fabric) as well as to plastic.

This is a very interesting project, and a puzzle, too!

Sue

Well, that's an ambition - to cross the Pacific???
DavidO

I love my paper mache canoe. while I was building it almost everyone said it wouldn't work. except those who had built boats or knew something about boat building or papermache. I did use the epoxy to waterproof the exterior and interior and it worked well. the sides flex in and out and the epoxy doesn't crack. I was worried about this but I think it has similar qualities as fiberglass and does flex without cracking. I guess it would depend on how much it's flexed. the sides of my canoe can flex in about a 10mm (if picked up wrong) without cracking.

after seeing my canoe a lady told me they had built some paper mache boats on the farm as kids. I think they coated them with some paint or something. they used them for a while and then they started to get waterloged. they leaned them against the back of the barn and the rain had got them soaked through. then the cows eat them.

Eaten by cows? How organic! No I'm not planning to travel very far from shore.

I'd love to see photographs of your canoe, Don.

In Vietnam the basket boats are constructed from various selected species of bamboo. and yes they have been made for  centuries as the coracle is thought to have been a coexisting development from the time of the dugout canoe in Asia, Iran and Great Britain.It is indeed a prehistoric craft.Some researchers suggest that it was used by the Celts to colonize the British Isles.

In Vietnam a coracle usually last about 6 years with everyday use as they are a major fishing and transport craft along the coast and up rivers. They are now also a tourist attraction as any image search will confirm.

Personally, I wouldn't proceed with building a paper canoe as the structural aspects are much more challenging than a 'floating bowl', especially in trying to consolidate the backbone of the thing. The beauty of the round coracle -- even compared to the British oval shape (eg; the Ironbridge Coracle is a classic design)or the pear shape used on one Welsh river -- is that it is structurally balanced and the forces from the water are  more evenly shared. That doesn't impact on where you put your feet or where you sit, but it makes for a simpler challenge in regard to reinforced structure. I'm also intending to add some buoyancy apparatus as all coracles will sink if they take in water.

While  I'm not going to paddle very far at all,merely a few metres from the shoreline  handline  fishing (as I say, around inlets and shallow marshes) it's still worthwhile getting inspired and I recommend reading N. H. Bishop-- Voyage of the Paper Canoe,  1878 online at:
http://www.ibiblio.org/eldritch/nhb/paperc/intro.html
He paddled it down the east coat of the United States.

Some folk have  journeyed the length of many of British Isles rivers  (eg: 8o kilometres was one journey) in their coracles, and one Welshman paddled across the English Channel in his.

In another example , two Welshman intend to paddle across  the English Channel in their canoe made from  boutique waterproof paper they make from sheep manure. Their first attempt was abandoned after their hull took in water.

"We thought if we can make a pooh canoe and paddle it across the channel for charity ," one of them told the media, so they could do right by Welsh Air Ambulance.

In further example, Dave Friant, a civil engineer,  makes canoes from cardboard
http://www.thecardboardboatbook.com/
and sells the DIY book.He reckons he has solved the waterproofing issue  by relying on coatings that are "environmentally friendly".

As part of my continuing research I'll be getting myself a copy. He also offers links to a range of other paper boating resources such as the Cardboard Boat Museum and the Rockport Paper House
http://www.thecardboardboatbook.com/$_alternate1.htm

Last edited by ratbagradio (2009-12-16 00:30:06)

Cat's suggestion of cloth got me thinking --so I purchased a cotton/linen blend today  and have laid some down on my experimental model boat. I boiled the cloth for 15 minutes first. To my surprise it adhered easily to the underlying paper layers.

I will experiment with cloth  on cloth and note the cloth mache threads here in this forum.

I'm really working the paper and the cloth into the form as I'm a once upon a time sports masseur and I got into sculpting because I trusted my hands' creativity. So I like to really put a lot of pressure on the material with my thumbs.

This is my first model and once I've coated it with  chosen coatings I'll be leaving it to float -- loaded with stuff -- in a water trough long term to see how it performs as to strength, buoyancy, and permeability. I even hope to weigh down the model so it spends some time on the bottom. After salvage I'll check the design's  weak points.

With the cloth my challenge is to work out how best to lay it down.  In way of technique  there are a few options.

1) Treat it like paper and layer it strip by strip, one on top of the other.
2) Cover a large surface by cutting slits in the cloth and  mitre-ing the folds then firming  the folds down, maybe even removing overlays.
3) Layer the cloth side by side in strips or patches. so that there is no bumpy overlay.

Technically as Cat suggested I could almost use one sheet of cloth and simply cover the hull with that by slitting and trimming where necessary. However I still need the paper to create the shape and deepen the thickness of the hull.

But it seems to me if the cloth really adheres without any hesitancy I can mix and match paper and cloth layers while noting that the cloth is going to shrink as it dries maybe more than the paper will.

I am then forced to wonder:What happens to paper or cloth if they are forced to cohabit with one another for years? What leaches? Is there a significant acidation? Does shrinkage stabilize? Will both media flex or bend  or dent in unison with one another, or will they pull at each other's adhesion?

Last edited by ratbagradio (2009-12-19 13:44:42)

I have been researching this challenge in the hope of deciding on a project plan.

The whole question of waterproofing is not simply limited to papier mache . Wooden boat enthusiasts face the same  problem with their preferred material so I was keen to address waterproofing from a wooden boat POV.

Traditional coracles are built using bitumen covered cloth for waterproofing  but bitumen paint would be too heavy for paper .

Another factor is cost. Marine waterproofing paints are many times dearer than domestic paints.

Furthermore the seemingly straightforward solution of using 2 pack epoxy -- yuk! -- assumes that the finished boat won't  be flexing as epoxy creates a rigid surface.

So I'm thinking of adopting a very radical and rather lateral 'solution' -- assuming it is a solution. I plan to use housepaint acrylic  and an oil soaking ingress agent.

Once I have laid down several paper layers ( number?)for the hull, I paint the external surface with several coats of acrylic house paint and let it dry. I then flip the hull over and paint the inner surface with acrylic paint as well so that both paint jobs meet each other and merge within the paper layers between.

Acrylic is waterproof when dry and in effect presents a  latex like layer. By doing inside/outside I create two concentric layers of acrylic. Then while the  final inner coating is still wet  I use its tackiness  to adhere a new paper layer over the whole inside of the hull. (I'm thinking that I would have much less adhesion once the paint dries)

I then start laying down my internal structure of bamboo and coat that with more papier mache and cloth  layers to a  required thickness. I then paint this covered frame with several coats of acrylic to waterproof  them using the top layer as a means to stick on more paper. I do this to isolate and 'waterproof' each frame piece.

I let the paint  and paper dry

I then coat the frames and hull  with more paper mache several layers thick.

I'm not sure yet whether I can apply this concurrently or not yet (I have yet to complete experiments)-- but I want to use  Penetrol
http://www.floodaustralia.net/products/penetrol.htm
as a waterproofing agent. Penetrol is a modern version of linseed oil for waterproofing  boats and you layer it into the surface so that it takes up the oil to saturation point. My notion is that if the acrylic layer leaks, I can rely on the Penetrol soaked layers to hold long enough for me to return to shore.

Jackie Hall's excellent article here on Waterproofing Papier Mache(2005)
http://www.papiermache.co.uk/articles/w … ier-mache/
captures some of the frustrating contradictions that appear to unravel when you  try to waterproof items. But it seems to me that if you intend to touch up the surface on a regular basis you are not asking of a coating to persevere unattended for ever.

In her sample the test was confused by the fact that she used a oil based house paint  ('Gary Gloss') and a outdoor acrylic paint which was brought in a hobby/craft store('Angela Acrylic') when the research and the technology has gone into acrylic outdoor house paints over the last ten years such that they strongly now out perform oil based paints.(She also suggests that some craft supplies are over hyped)

Similarly below these top coatings there was no form of waterproofing.

This is the complication of boat coatings. While underwater and above water line  is one important factor, how long the boat stays in the water immersed is another. And  this  article on Acrylic Paint for boats by Dave Carnell
http://www.simplicityboats.com/latexcarnel.html
puts choice into context -- and he has been painting boats since 1951.

The complication I need to point out is that you cannot mix Penetrol -- or Linseed oil -- with Acrylics although you can mix/blend Penetrol with oil based paints (but not 2 pack expoxies). So I'm trying to get around that by allowing the acrylic paint medium to  consolidate and dry first before working in the oil. How well they will co-exist inside the papier mache remains to be seen.

Last edited by ratbagradio (2009-12-25 10:49:41)

Oh I know that the oil won't penetrate the acrylic -- that's either a plus or minus. And I do indeed have several scale models made each designed  with and for different coating materials.

So how the coatings co-exist and whether they actually provide some significant waterproofing is now being tested in  my kitchen laboratory.Unfortunately, at the moment here it rains every day and is hot and humid so papier mache -- just like washed laundry clothes -- take so long to dry.

You are really going into this with great gusto! I was interested in the products you are experimenting with. I am familiar with Dulux weathershield - I painted the front of my cottage with it about 13 years ago and it is still as good as new. I've not heard of the latex paint additive before though. Is it new?

Maybe one or both of these products will help our floating teacup artist?