How big is your tippet...REALLY?

I have fished a lot of different tippet brands over the last few years. Over time, I found a few I liked and started doing comparison knot tests. Several popular brands seemed surprisingly weak compared to those I had started to favor. But as I looked closer, I realized there was likely one simple reason why. 

My suspicions came to a head while I was sitting on a beautiful river south of the equator this past January. I had just broken off a fish and needed to rerig. I grabbed the spool of 5.5x Trouthunter tippet I had been using. I pulled on the tippet and the spool ran out. I had a spool of 5.5x tippet from another company left in my backpack from the previous year's trip. I pulled off a piece and went to rerig. Before I did, I held both pieces of tippet in my hand. The tippet I was about to switch to was considerably larger visually than the Trouthunter I had been using despite the fact that both spools claimed they were 5.5x tippet. With no other choice, I used the larger tippet, but I could immediately tell that my nymph drifts were faster and I was forced to switch to a heavier rig to try and slow them down. 

After this experience, I decided I needed some empirical data. I purchased a digital measuring microscope with magnification to 200x. The microscope is precise to 0.001 mm, which is certainly precise enough to compare measured diameters of tippet.

It has been a busy spring, but I recently made some time to sit down and measure all of the fluorocarbon tippet we sell in our store at tacticalflyfisher.com. Below is a photo of what the tippet looked like on my computer screen. Each measurement was from edge to edge of the tippet. I calibrated the microscope using the provided calibration ruler at the beginning and ending of each measurement session. I did not observe any measurement drift within or between sessions. Therefore, while I do not know the true accuracy of the microscope I used, it was consistent across my measurements. 

I took five measurements from a spool of each diameter of each tippet type over several feet of tippet. It would have been nice to have taken 30 measurements from multiple spools of each tippet, but I simply didn't have that kind of time. If you want to quibble with me over the statistical validity of my methods that's certainly fine. While the sample size for each individual tippet was small (n=5) and I didn't use any frequentist or Bayesian statistics to look for "statistically significant" differences, the diameter discrepancies I observed were noticeable and repeatable even if they wouldn't stand up to peer review for a journal. I've reported a highlights version of the results in a video on our YouTube channel, which you can watch at this link. 

Before I dive into the results, the table below is a reminder of what the diameters should be for each size of tippet using the X system for tippet diameters. Keep these diameters in mind when we reach the measured diameters.  

As I mentioned in the YouTube video, the tippet X system dates back to the era when fly fishing tippet was made from catgut. In my opinion, it's an antiquated proxy at this point but the inertia of fly-fishing tradition is keeping it in place. You can do some scouring of the internet if you're interested in knowing more. 

So, without further ado, what were the results of my little study? Here is a table of all tippet types ranked from most accurate to least accurate. The average difference column is an average of averages so to speak. More specifically, for each tippet diameter, I computed an average diameter (mean) of the five measurements I made for each tippet. I took that average and compared it to the normal X system diameters to find the average difference between the measurements for each tippet and the expected diameter. Then, for each type of tippet, I computed an average of all of the differences between the measured and expected diameters to form the overall average difference for each tippet type. Clear as mud? (Note: we were out of stock of on size of SA Absolute Supreme and one size of Rio Fluoroflex Strong when I made these measurements. I plan to update the results when we have them back in stock which could slightly shuffle the results.)

As you can see from the table, on average, all of the tippet types were larger than what the true diameters would be at each X diameter. There were considerable differences in average tippet sizes which became more apparent when digging into the measurements for each diameter of tippet. So, let's dive into each company and the measured sizes. To make things easy, I'll cover each tippet type by the order in the table above. 

Trouthunter fluorocarbon was the most accurate tippet I measured. All of the sizes were less than 10% different from the stated size. The biggest difference was in 6x tippet, which measured 8.5% thicker than what 6x tippet should be. However, I found that 6x was commonly large in other brands as well. 

Airflo Premium Fluorocarbon was the second most accurate tippet I measured. All the sizes were within 10% of the expected size except for 6x, which was 11.6% larger on average than the expected 6x diameter and was nearly as large as their 5.5x tippet. 

Scientific Anglers Absolute Supreme was the third most accurate tippet I measured. Absolute Supreme is Scientific Anglers' more expensive premium fluorocarbon offering. Their 5x diameter was the most accurate diameter I measured throughout the full test. Following the pattern from the previous two companies, their 6x was 10.4% larger than the expected diameter and could be considered 5.5x. Considering that accurate diameters are a key part of Scientific Anglers marketing for their Absolute tippet, it is good to see that their tippet ranks near the top of the accuracy chart.  As a reminder, we were out of the 7x diameter when I took the measurements. I will update the data and results when we have it in stock. 

Scientific Anglers Absolute Trout fluorocarbon tippet is their lower priced fluorocarbon offering. Its average diameter difference was very close to their more expensive Absolute Supreme fluorocarbon (6.1% for Absolute Trout vs 6% for Absolute Supreme) though the individual measurement differences were noticeable. The Absolute Trout 2x tippet was one of the few tippets I measured during the test which was smaller than the expected diameter. All of the sizes were within 10% of the expected diameter except for 4x, which averaged 12.9% larger than the true 4x diameter. 

Native FX is a new tippet material for our shop. I have not had the chance to fish it yet. In general, it was fairly accurate. I computed the average differences based on the diameters stated on Native's labels. However, Native has some stated diameters that don't correspond to the normal diameters of the X system. I have highlighted those diameters in the table with red font and provided a separate column for what the differences would have been relative to "normal" X system diameters. Obviously, their ranking would have shifted if I had factored the second column into the overall brand average for their tippet. 

Rio's Fluoroflex Strong was at the middle of the table for overall accuracy. On average, their tippet was 7.8% larger than normal X system diameters. The smaller sizes were proportionally less accurate with 6x at 13% and 6.5x at 10.2% larger than their respective diameters. 7x was also fairly large at 9.8% larger than the expected diameter. One important note, we were out of 5x when I made the measurements. I will update the data with that size when we receive more. 

Soldarini S Power Elite fluorocarbon is a relatively popular mid-priced fluorocarbon. Soldarini also lists diameters on their labels which do not correspond directly to the X diameter system. Some of these diameters are smaller than what they should be, and others are larger. As a result, I have listed columns for both the % difference from Soldarini's stated label size (red font) and the % difference from the normal X system sizes. Proportionally, the larger sizes were more accurate than the smaller sizes. The 5x-8x sizes were all 10% larger than Soldarini's labeled diameters. Furthermore, the 7x and 8x diameters were considerably larger than the standard X system sizes. 

Moving lower in the table, Umpqua's Deceiver X was next. Deceiver X is Umpqua's mid-priced fluorocarbon tippet offering. Most of the sizes were relatively accurate but the 6x diameter drastically skewed the overall average size difference for this tippet. The 6x tippet measured 0.0062" on average, which is slightly larger than what 5x tippet should measure. We had a sad laugh in the shop because this is the tippet that our warehouse manager Justin used for years. Now he knows why it was so strong compared to other 6x tippets he tried. 

Moving toward the bottom of the table, Cortland's Ultra-Premium fluorocarbon was 11.9% larger on average than it should have been. As you'll see from the table, the diameters become less accurate as the tippet gets smaller. I used Cortland's 7x fluoro for quite a few years. I didn't know one of the reasons why I liked it so much was because it was closer to the diameter of 6x tippet.

Umpqua's Phantom X tippet is their premium fluorocarbon offering. On average, it was 14.7% larger than it should have been. Once again, the smaller sizes were the least accurate. The 5x diameter measured larger than what normal 4x diameter should be. 6x and 7x were both nearly one size large as well. 

The least accurate tippet in the test was Fulling Mill's Masterclass fluorocarbon. Fulling Mill states diameters on their labels which are larger than the normal X system tippet diameters. I have highlighted those stated diameters in red in the table. I have also added a second column for the % difference from the normal X system diameters. All sizes of Fulling Mill's tippet were more than 10% large regardless of whether the diameters used for comparison were those on the label or the normal diameters from the X system. On average, Fulling Mill's tippet was 14.1% larger than their labeled diameters, and 16.4% larger than the normal diameters of the X tippet system.

This test provided some useful information for me to make my own tippet purchases. I hope the information will be useful for you as well. 

 

Devin