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Fibreglass weave question
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Author:  diplomat [ September 6th, 2005, 11:58 pm ]
Post subject:  Fibreglass weave question

I was asking a friend about a source for fibre glass and he asked me a question that Ted Moores' book doesn't deal with (that I can see).

He wanted to know if I wanted tight weave or loose weave. I said I would guess loose weave to make sure the epoxy sinks in better.

Is this correct? Is there any difference in suitability? Price?

Thanks in advance! 8)

Cal White

Author:  Bryan Hansel [ September 7th, 2005, 12:32 am ]
Post subject: 

I would guess that by loose weave he is talking about standard fiberglass. Tight weave is much harder to wet-out, but uses less epoxy. I made a very light canoe one time by using three layers of 3.5 ounce tight weave. It was pretty fun to work with because it hardly used any epoxy at all.

Author:  Komatiq [ September 7th, 2005, 1:09 am ]
Post subject: 

Hi Cal, there is some differences between manufacturers, the better ones being more consistent with their weave but "open" may be better explained by weight than anything else.

Like Bryan mentioned "standard" glass or "e-glass" is more open than s-glass which has quite a bit of binder added that helps fill the weave a bit. While e-glass is far easier to work with (conformability) than s-glass it isn't quite as strong a fabric.

E-glass also wets out far easier than s-glass, no binder to try and saturate.

In Canoecraft the weight mentioned most often is 6oz fabric(e-glass). A heavier weight would be a more open weave since the actual strands are heavier and allow more gap when they overlap in the weave. Lighter fabric (6 or 4oz) is normally always fairly tight weaved and easy to conform to the hull shape. Those (4/6)would be better for strip construction for that reason.

As for cost it normally goes by fabric weight so the lighter ones will be the more affordable.

Hope that is some help.

Author:  dreamstream [ September 7th, 2005, 8:03 am ]
Post subject: 

Resin is a part of the cost also, some places charge more for 4 oz than 6 oz cloth. Likely because of sales poularity of 6oz. 4 oz cost a bit more than 6, but you save on the resin.

Author:  Rolf Kraiker [ September 7th, 2005, 9:13 am ]
Post subject: 

I've seen some canoes made from a cloth called woven roving. This material is a little better than chopper or mat construction, but it's pretty much at the bottom end of the quality scale as far as I'm concerned. It is a VERY loose weave so it might be worth ensuring your friend didn't have that in mind when he asked the question. Woven roving would not be used as a covering over wood strip construction, it would be used inside a mould as it's usually 18 oz cloth.

Author:  jjoven [ September 7th, 2005, 9:25 am ]
Post subject: 

I have worked with both. The glass refered to in Canoecraft is standard 6 oz e glass. It is usually loose weave. For me, loose weave was easier to work with. It conformed better to the hull. It wetted out nicely. But it also uses more resin.

I used some tight weave 5.7 oz on my football as an additional layer. It was tough to wet out and I wound up with many little ripples in the hull which I had to sand out and apply an extra layer of resin.

That said the next canoe I build will probably have a couple layers of 3 oz tight weave instead of one 6 oz loose. Less resin, lighter boat.

Here is a supplier that has all kinds of glass. Just reading their fabric descriptions will give good information on tight weave, loose weave, e and s glass.

http://www.thayercraft.com/

Author:  Dan Lindberg [ September 7th, 2005, 11:28 am ]
Post subject: 

To add to jjoven's post,

study the offering's on the thayercraft site, and also go to the weaver's sites and down load the cloth data. Then you will get a good idea of what is available.

But briefly, the terms "tight" and "loose" are a bit confusing, as cloth, whether E or S, comes in MANY different weave patterns, as an example, you might find 4-5 patterns that are all about 6.0 oz give to take, and they could all be different, with different strength values.

Also note that in general, the lighter, finer weaves (with smaller threads) are stronger per lb then the heaver, larger weaves (with thicker threads). For example a 3.2 oz "fine" weave (#1678) can be just as strong as a 6.0 oz course weave (#7633).

The "standard" 6.0 oz (is actually about 5.8 oz) has a breaking strength of 220 lb in both warp and fill, on my current project, using combinations of 2.3 and 2.8 oz, the calculations show a 10 lbs weight reduction but the strength is 3.0 (fill) and 3.1 (warp) times on the bottom. The sides are 1.3 (fill) and 1.9 (warp) times the 6 oz strength.

The finer/tighter weave patterns do wet out harder then the more open weave patterns.

Dan

Author:  jjoven [ September 7th, 2005, 12:08 pm ]
Post subject:  Hey Dan

Dan, did you use style 2113 on your current canoe? How did it work? Conform and wet out? It doesn't look like a"tight" weave.

http://www.thayercraft.com/2113%20DETAI ... ICTURE.htm

Image

At those prices and inventory I have been considering getting a bolt.

Author:  Dan Lindberg [ September 8th, 2005, 2:24 pm ]
Post subject: 

Hi Jose,

Yes, I used #2113, a 2.3 oz material for re-enforcing on the bottom, 2 layers crosswise to the canoe. 2113 has a breaking strength of 195 lbs in warp and 75 in fill, it's layed so the 195 lbs is across the canoe.

There is also 2 full layers of #7516, a 2.85 oz material with a strength of 205 lbs warp and 145 lbs fill.

The bottom has a "combined" strength of 560 lbs lengthwise to the canoe and 680 lbs across, the sides are 290 and 410 respectively. This is per side, in and out.

Std "6" oz is 220 lbs by 220 lbs.

As for the wetout, yes, the 2113 is difficult. :)

I also used it on the last project, 4 layers in and out. I use a nylon brush to wet the cloth, working the resin in a bit at a time. I used System 3 Clear Coat, as it's the least vicious resin I could find. Only mix about 4-6 oz at a time, as it changes properties before you can get it all on, and then it doesn't wet out very well, it has to be fresh.

If I could come up with system to roll the resin on and then lay the glass, that would probably wet out much better and use less resin. I used too much resin on this wetout, it's very easy to put on too much with the light cloth, I went to wetting 2 layers at once to reduce the floating.

The cloth conforms to the hull OK with a little rubbing at the "off" angles, like std cloth does, it just takes a bit more work.

As for Thayercraft, yes, they have very good prices. I bought a roll of each weight for just a little more, maybe $50, then buying what I needed from other sources. But now I have enough glass for several more projects. :)

Also, what I got was very nice material, full rolls in unopened manufacturer's boxes. It is a bit old however, so keep it sealed, I think I read some place that the coating they apply can "evaporate" off if it's exposed for long periods of time, ie, greater then a year say.

AND he shipped me the glass almost the same day I called the order in and billed me later and excepted a personal check for payment.

He only sells either full rolls or small pieces though, the small pieces mainly on e-bay.

Dan

Author:  jjoven [ September 9th, 2005, 9:12 am ]
Post subject: 

Dan, where can I find the warp and fill strength information for different weight fabrics?

Author:  Dan Lindberg [ September 9th, 2005, 11:07 am ]
Post subject: 

Jose,

The Sweet site has a good description of glass and terminology.
http://www.johnrsweet.com/Fabric.html#Gfab

Two large weavers are Hexcel and BGF.

Cloth data can be found on the Hexcal site.
http://www.hexcel.com/Products/Download ... ata+Sheets

BGF also has data but I don’t offhand have their address, do a search.

Or send me a e-mail and I’ll send you an excel file I have that lists the offerings from both companies. dan.lindberg@baesystems.com

Dan

Author:  Doug [ September 9th, 2005, 11:10 am ]
Post subject: 

May be of interest,

http://www.oneoceankayaks.com/Abrasion.htm

Doug


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