My 2 cents on Bear paw crystal clear glass...

[Mike Mecredy]

It's been a while since I posted on here but I do read the posts from time to time. 
 Back on topic, I don't use a lot of clear glass, because my customer base generally seem to shoot simple plain looking bows that I have some how been "type casted" to build.  But when I do get a customer wanting clear glass I found myself ordering just a few strips of Gordon's from Bingham's.  The gordon's glass worked, but there was always the issue with uneven clarity and that was thorn in my side.  So I took the leap and I ordered an entire roll of the bear paw, crystal clear, fiberglass do to the rave reviews it was getting.   The first thing I noticed was it seemed lower in mass than gordon's glass of the same thickness and width, and also not as rigid.  My first trial run produced a longbow that was 5 lbs under weight.  I made it based on data I recorded on builds using gordon's glass.  What I found though, and I hope this is helpful, no matter what design I make, if I make it with bear paw clear glass, and I make it 1/8" wider than I would with gordon's glass I nail the draw weight.  Another thing I found remarkable; in spite of being less rigid, the bear paw glass seems to have a bit more snap and speed than the gordon's glass, in addition to being crystal clear, as the name implies.  I suppose I could have recalculated the stack thickness to compensate for the difference in rigitity, but adding the additional 1/8" to the width is more practical and it gives the wood beneath that extra bit of width to show through.  I hope this is helpful.  And one more thing, BCY formula 8125 is AMAZING!  Give it a try too.

[Flem]

You are not the first to make those discoveries. It's been talked about recently in the different thickness thread and all of the manufacture's specs are listed. Check the glass to resin ratios to clarify your observations.

[kennym]

Mike,

Not sure when you got the roll, my first couple rolls came in 5# light too, then suddenly I was coming in heavy. Finally narrowed it down to the glass, after  checking my math and pulling my hair.   So with adding 5 lb to my stack and the BP now being stiffer (.040 checked about like .044 worth of Gordons) I was back on track after a couple 12# over bows!

Now with a spine tester on my cut table, after 2 rolls of stiff stuff, the next 2 rolls have spined exactly the same as gordon's.   It was only the .040 x 1.5, the  .040 x 1.75 and the .050 x 1.5 were same on all I checked.

Hoping they keep it like this!

[Mike Mecredy]

Hi Flem, I did a search on the bowyer's bench, of 1/8" and it didn't show any results, so actually I am the first one to mention here, what I've found in regards to bear paw crystal clear glass and adjusting limb widths, according to the tradgang search engine. 
      Others have mentioned adjusting the stack thickness, but considering just a few thousandths of an inch in thickness will result in a wider deviation in draw weight than making a limb fractionally wider will, I thought I'd mention it. Additionally, if one does make the limbs wider, and it comes out too heavy, it's easier to make the limbs narrower to reduce the draw weight, than reducing draw weight, if the limbs are made to thick.  I've done both and reducing width is easier.  Because how how it goes, Twice as wide = twice as heavy, twice as thick = 8 x as heavy.   Again, I just thought I'd mention my own experience with the stuff.   

[Flem]

Yeah, sorry I was not clear. I was referring to your observations on mass, rigidity and weight comparison to Gordons.

[BigJim]

After going through more than 20 rolls of the Bear Paw, it was time for a change. I found it to be less clear than the new and improved Gordons glass and with every roll, there was a change of formula.

 I've been told by a big company that does testing that I would trust, you will loose a couple feet per second with the BearPaw.

I have been through a couple hundred strips of Gordons personally this summer/fall and I must say that the consistency and clarity is considerably better than the Bear Paw.

I still sell both Bear Paw and Gordons because there is a substantial price difference.. and I'm trying in vain to make what I have a profitable business.   I must say that my non scientific findings of the bowyers out there parallels that of the traditional customers out there.
They love to complain about the quality of an item, but are for the most part unwilling to pay up to get better quality. My margins are probably a little better on the BearPaw as there is no quantity discount unless you purchase a roll.
Bowyers that buy quantity generally buy the Gordons.  (again, just my observations)

BigJim

[fujimo]

i clearly remember when a similar topic came up just when the bearpaw glass was making its appearance.
At the time, i too was disheartened with Gordons clarity. i was communicating with a few other glass makers in Europe, some who made glass for skis, others in the aeronautical industry.
i settled on one manufacturer, and got some sampling sent over, i sent it to a local bowyer. sadly, it wasnt well received.
which was fine, in hindsight it probably saved me a lot of heartache and financial ruin
i guess i had dreams ( unrealistic) of importing and distributing a better quality glass.

well the bearpaw made its appearance, and seemed to alleviate the problem at the time.

However, based on extensive personal experience within the aramids  and glass industry, and more importantly going on what these pretty hi tech manufacturers in Europe were educating me on, was that, in order to get a higher tensile strength - which would  relate back to the "spine" of the glass, you needed to have a higher glass to resin ratio. but that is fraught with reductions in clarity, and the "dry streaks" which are actually  inadequately saturated glass strands, during the extrusion process.

i remember looking at the BP glass specs and seeing its glass to resin ratios were lower than gordons, but it did produce beautiful clear glass.
anyway, its sad to see the whole cycle being repeated again.
in order to ensure strength and durability of ones bows, especially if they carry a 30 year warranty, i guess the glass needed to be strengthened and stiffened somewhat, but that has now lead to the loss of  some of the clarity.

i wonder what gordons new, clear glass's ratios are, and how they compared to the original glass ratios.

i would imagine it has to be really  tough trying to find that balance between clarity and glass to resin ratio.
especially when the market for glass for bows is a drop in the ocean compared to all the other applications, skis( snow and water), skateboards, aircraft etc etc

its awesome to hear that gordons has some good glass, and at least we can carry on making bows, will be interesting to follow this all, and see how it all pans out.

[Buemaker]

Well, I am glad that I still have my Swedish Bjorn glass. Have always been clear.

[Crooked Stic]

Yeah this is the 3rd or 4th time since I been making bows that Gordons has made a come back with better glass be interesting to see how long it last this time.

[Roy from Pa]

Wood is free, it grows in dah woods:)

[BigJim]

With every industry there is change. Back and fourth, give and take. When new materials or different shipments occur, things can take a turn for the ??? well, who knows.

Gordons has been through this many times and I would hope they have learned. The consistency in spine of their glass has always been better than the rest.
For the longest time, the Bear Paw glass was so hideous that the price was the only way to get someone to buy.
They had a moment with clarity then made a change in glass/resin content...from what I understand and then they can't understand why they lost clarity. It is still good glass, just not very consistent in spine and clarity.

BigJim

[Buemaker]

This is the company who makes the Bearpaw glass.
http://www.isosport.com/en/

[Sant-Ravenhill]

Thanks for sharing this information. It definitely saves time and money for a hobbyist such as myself.

[Flem]

Ditto, thanks Bue. Interesting that isosport and Exel both make 30/70 resin to glass laminates and Gordons make 70/30

[Crooked Stic]

So Gordons is 70 percent resin and 30 glass. Know beans about making glass but that seems a small percent of glass??

[BigJim]

i wouldnt believe that...

[Flem]

Don't worry Big Jim, I don't make s#!t up.

[fujimo]

Flem, i think it says that gordons are 70% glass by weight!

[BigJim]

Never said you made anything up Flem, but that sure reads as 70% fiber filler by weight to me.

Gordons had the highest ratio of glass to resin ... back when BearPaw was clear. I would suspect that BP had isosport bump up the glass ratio due to the lack of spine and loss of performance, hence the up and down spine issues causing a lot of missing weight.
When pressed about the clarity, I was told ... they didn't know what the problem was.
Now, i'm not saying that the Bp glass is horrible, but it isn't as streak free as Gordons or as consistant.
Having said all this, I still sell both, but choose to use Gordons.

BigJim

[Buemaker]

When Isosport developed the clearer glass for BP I contributed in a modest way by giving Isosport some information.
I sent them samples of the Swedish Bjorn glass to investigate. That glass have always been clear. Hoyt used it for many years. Another American firm named 20th century or something also used Bjorn glass. The Bjorn glass was more expensive than others,and I guess people tend to buy the less expensive stuff. Bjorn glass also come sanded on both sides.
Isosport told me that Gordon and Bjorn use a resin named Vinyl Ester while Isosport use an epoxy. If one of the two are better than the other I do not know.