My friend from the club gave me four pieces of the old strings. She said me they are maybe 20 years old gut strings. There is BABOLAT DOUBLE LINE printed on the surface. I´d like to use them only to do some experiment - i´d never played with gut strings before. So I have some basic questions for everybody who knows: It´s good to prestretch gut strings? What´s the reasonable tension of gut strings? I´d like to test the hybrid stringing - mains with Yonex BG65 and crosses with gut. What do you think about it? Thank you for the comments.
It's not only good to do so, I would go as far as to say it's necessary - gut has a distinctive tendency to twist up, which prestretching will ameliorate to a large degree. Depends on the thickness, but you should be able to take 0.70 or thicker into the high 20's with ease. I've actually done this already (with Zymax 67 mains) - see here. I hated it, but your results may vary; bear in mind I now use 32 lbs with 0.68 (or thinner) strings.
if they are 20 years old then there isn't much point in using them, they will probaly break quite easily if they are 20 years old. And plus they are gut strings which tend to be less durable than synthetic strings. So my advice would be not to use them, and just keep them so you can sell them in another 20 years for a nice big some of money.
I am not sure if this is a nature gut or synthetic gut string Any bio matter degrade over time. Even in air tight seal. Just think, body still decompose under ground in a sealed box. So, imho, I would just frame it up and keep it as museum piece if it is a nature gut. If you really want to use it and if my memory serve me correct, the max nature gut tension at that time is 20lb. at this time, it will prob take 18lb at most...