On a Flemish twist string, do you do back twists before you start making the second loop?  Is it necessary?   

If it is truly better, how do you know which direction to twist the individual bundles?  And how many back twists do you need? 

Thanks for any tips and advice.  - Chad

You need back twists if you want it to blend well. Put the back twists in each bundle before starting the second loop. The easiest way for me to do it is to pay attention to which way I untwist and straighten the bundles after finishing the first loop, then put the back twists in the same direction.

Build them the same way each time and keep good notes. Material, type and color, bundle length and strand count, # of twists in the loops, length of the fade outs, padding if you use it, # of back twists, stretched finished length, etc...

I recommend the video "how to build a great bowstring". I bought it years ago and it shortened the learning curve quite a bit for me.

I agree with Artic Hunter.

You don't need to put in back twists.  I made strings for years before I ever heard of back twists.  They all worked fine.

However, the string looks better with backtwists, and now that I know about backtwists, I wouldn't make a string without them.  Without backtwists, a string looks like two separate bundles twisted together (the term is cabling).  With backtwists, as Artic said, it looks more blended together.

The idea is to put in the same number of backtwists as the twists you will add when you make the second string loop, so that there will be no twists in the body of the final string.  But that's a little hard to figure out, and really not critical.  I just untwist the twists in each bundle after making the first loop, and put in 10 more backtwists in the same direction as I was untwisting.