Dumb Luck…
I am blessed. 
I’ve trimmed my wrist and neck gaskets on two drytops and a drysuit without any problems.
When I first got the drysuit. I tried well over a week to stretch the neck gasket with no luck and finally resorted to trimming. Fact is that I have medium girth body with the length of a small. No way am I ever going to be able to stretch to make the gaskets fit. But if the gasket is just a tad tight, the stretching method may the way to go.
sing
Stretching does not shorten seal life.
I have had five year spans from stretched gaskets. Hard to beat that. And if you think it out, you will realize that the remnant left after cutting is going to go through just as much stretching IN USE as an uncut gasket which has been stretched.
So, now we have companies supplying wrist gaskets which are not even DESIGNED to be cut. You can stretch now with a plastic soda bottle, or you can stretch later with your (uncomfortable) wrist, but on the Stohlquist I just got, they meant what they said. Those wrist gaskets are not meant to be cut.
Drysuit rip
It is a brand new suit, NRS EXTREME, and I was being totally careful. I made a very straight cut, had virtually no curves or sharp edges, and when I tried to slowly peel it off from the can it just broke loose with a gash. It must have caught on a sharp edge. Thanks for you help, I’ve ordered a replacement in a larger size that I will glue back on.
The Bassman
Stretching & Stohlquist instructions
– Last Updated: Nov-14-04 9:39 AM EST –
Stretching causes microscopic tears in the latex. That's what causes it to become looser. That's damage and it will shorten the seal life.
"I have had five year spans from stretched gaskets. Hard to beat that."
You're either lucky, you take very good care of your seals, you don't use your garments much or a combination of the above.
"And if you think it out, you will realize that the remnant left after cutting is going to go through just as much stretching IN USE as an uncut gasket which has been stretched."
If you have a seal that's 1.5" in diameter and you stretch it over a wrist that's 2.5" in diameter it stretches 3.14" (pi x the difference in diameter). If you trim the same seal so that it's 2" in diameter, it only has to stretch 1.57" - half as much - to accommodate the same size wrist. Do the math and see for yourself. Even if the seal has been permanently stretched, it still has to stretch further to accommodate the difference in diameter and the total amount of stretch required is the same. It's still twice as much as the trimmed seal.
"So, now we have companies supplying wrist gaskets which are not even DESIGNED to be cut. You can stretch now with a plastic soda bottle, or you can stretch later with your (uncomfortable) wrist, but on the Stohlquist I just got, they meant what they said. Those wrist gaskets are not meant to be cut."
While I have seen NEOPRENE seals that are not meant to be trimmed, ANY latex seal can be trimmed. I'd love to see the Stohlquist information you refer to, at they have been proponents of trimming latex seals all along. Here's a quote (complete, typos and all) from the tag that was on the Stohlquist Gore-Tex Gripp jacket I bought last year:
"Fitting - Latex Gasket Seals
Seals on new suits may need to be trimmed for propter fit. Gasket latex has excellent memory, and does not stretch out with use. We do NOT recommend trying to pre-stretch gaskets. Trimming for proper fit reduces stress on you, the gasket, and their bond to the suit. Trim with long bladed, sharp scissors. NO SWISS ARMY-KNIFE SCISSORS. For neck gasket, use concentric rings as cutting line. Cut off one ring off, testing the fit and keep repeating as needed. Trim wrists very little, if at all. Ankles require aggressive trimming (1" or so for size large). Trim gaskets so they are only "slightly" tight, and so that YOU are satisfied with the fit, the comfort, and the restriction of water entry. Remember, a drysuit does not have to be absolutely dry to function properly. We, who paddle in drysuits regularly, feel a bit of moisture is tolerable; the discomfort from tight seals isn't."
I think that pretty much say it all. You can see the tag in my Drysuit Repair album on Webshots at:
http://community.webshots.com/user/brian_nystrom
Stretching shortens seal life
In multiple conversations with the folks at Typhoon Drysuits, I was told repeatedly that stretching will not increase the diameter of latex seals and in fact will shorten the service life. I trimmed hundreds of seals by hand with simple sewing scissors and no form. No prob.
Even more boneheaded
My drysuit has a horseshoe zip that starts on the chest, goes around the back of the neck, and finishes on the chest. It’s very comfortable, and allows me to pull the suit off partially to dry while still wearing it. Thursday I was unzipping, and lacking eyes in the back of my head caught the latex neck seal in the zip. D’OH!
One neat hole, the size of a pencil eraser…
Sounds like the Mustang dry suit…
…that Sing has. The zip looks funky, but it makes a lot of sense.
That’s the one
At first glance you’d think: “What the…” but the zip makes perfect sense. It lies in the most inactive parts of your torso, so never restricts movement, at least while paddling anyway.
It’s great to be able to unzip and pull the neck piece off to expose your chest for rapid cooling and drying. The downside is the awkward contortions required to get the zip pull past the back of your neck.
Sorry, threw the tags away. My
Stohlquist goretex was bought from Sierra Trading Post. The wrist gaskets do NOT have a series of cutting rings on them, and I remember quite distinctly that they advised against trimming on these rather heavy wrist gaskets.
Your reasoning is strained and stretched, producing many micro-tears. Many gaskets are not tapered enough to produce the differences in diameter you describe without cutting WAY back. Most people cut back enough that they simply have a narrower “rubber band” around their wrist or neck. That is what gives them the impression of acceptable comfort. As they wear the garment repeatedly, sub-microscopic creep occurs in the chains of latex, and the gasket gets more comfortable. When I stretch a gasket, I induce sub-microscopic creep along the length of the gasket. I end up with a wide zone of low force rather than a narrower zone of somewhat higher force. Before my five year old neck gasket finally tore (a little), it had become VERY comfortable because it subjected a wide area of my neck to very gentle force. This was a product of cautious initial stretching plus repeated but careful use. When the tear finally occurred, it traveled only about 1/2", and the gasket still sealed adequately. Probably the tear never reached the zone “upstream” of where someone would have trimmed.
If the manufacturers were so sure of what the proper long-life gasket diameter was for a given head or wrist diameter, I suppose more of them would have been advising a neck or wrist measurement, and that we then count back a specific number of rings and cut.
I want to make it quite clear where I do not agree with you. I believe that latex gaskets can be stretched to provide a wide, even pressure zone, and that if this stretching is done properly, there will be no “micro tears” causing vulnerability to failure. The latex molecules simple slip or creep along one another.
If you trim a gasket, there is a small risk that you will create a micro-tear along the cut edge. If you handle the gasket carefully, that micro-tear may never travel. But another thing will necessarily occur. The same stretching over time will occur from pulling the gasket over a large hand or a large head, as will occur when I systematically accelerate the process by using plastic soda bottles. And if your posited “micro-tears” are going to occur from soda bottles (a 3 liter soda bottle is smaller than my fat head), then they are also going to occur from repeated donning/doffing of the garment.
What you end up with is gaskets which have a relatively narrow pressure footprint, and which also “may” have micro-damage within that footprint. What I end up with is a wider, more comfortable pressure footprint. Almost certainly any “damage” from stretching, both soda-bottle and donning, occurs both in the wide area I have NOT trimmed, and also in the narrow zone which would have resulted if I had trimmed. I do not see how I am worse off. The stretching caused by the plastic soda bottles is actually rather mild compared with routine donning, especially in the case of the neck gasket.
It should be clear by now that neither stretching nor trimming has been proven by experience to be superior. I don’t recall treating trimmers as if they were stupid for trimming, and in the absence of a big pile of raw data obtained under controlled conditions, I do not intend to feel stupid for stretching. I prefer the result. I prefer the way a carefully stretched gasket fits.
Your mileage may vary.
Feeling stupid is indicative of an
ego issue. No one said anything to you to suggest that you are stupid. It is very clear that trimming gaskets is superior to stretching them, that is all that was being said. Perhaps you feel stupid because you so vehemently defend an idea that is discouraged by the very manufacturers of dry gear. Maybe you feel stupid because you continue to argue when you are obviously wrong. Why do you do that? Being wrong is not the same as being stupid. Continuing to argue when you are wrong is being stupid. -imho
Why is it very clear? We argue about
– Last Updated: Nov-14-04 9:42 PM EST –
this all the time on boatertalk.com, and in that much larger whitewater community, nobody has made it very clear. There are a few manufacturer pronouncements, but hard data is lacking. Are you still at that stage in your paddling career where you completely accept what the manufacturers tell you?
I just checked the gaskets on my Stohlquist, and the wrist gaskets, which were previously miserably tight, are now quite acceptable. The neck gasket is still somewhat tight, and is not responding as well as did the gaskets on my previous Kokatat drytops.
Sorry, have not heard of Typhoon
– Last Updated: Nov-14-04 9:35 PM EST –
drysuits. Can't think why you would have occasion to trim "hundreds" when each is trimmed or stretched just for the owner. Tell me, why were you trimming so many?
Here ya go
One of the world leaders in drysuit manufacturing.
http://www.typhoon-int.co.uk/products/products_thumb.cfm?ProductTypeID=11&CategoryID=1
I was responsible for testing and maintaining approx 1,000 dry suits used for helicopter transport in the North Atlantic oil patch.
Ah, very interesting. Can’t wait for
stretching to work in that kind of application.
'twould be nice to have some small
zippers or quick seal/unseal ports and some interior design so that routine paddling would tend to pump air through the inside of the drysuit. These could be sealed quickly when the risk of tipping or getting doused becomes significant. Might have to be coordinated with (or work around) PFD pressure at the shoulders, so that air could move in at the neck, perhaps, and then out along the arms.
straight forward it seems
I agree, natural motion of paddling would force ventilate. A simple quik seal on shoulder might work, out of way of PFD, accessible. Hey, anyone a marketer.
divers drysuits have an air release
valve on the shoulder, but it’s a check valve that only lets air out.
They can be troublesome
Helicopter transport drysuits have them at the shoulders and ankles (you DON’T want flotation in a submerged airframe) but they often fail. I have a Goretex pilot’s suit and a coated fabric passenger suit I use occasionally, but I injected silicone sealant into the valves to stop the leaks.
Of rings and things
– Last Updated: Nov-16-04 11:05 AM EST –
I have never seen ANY wrist seals with rings on them, nor ankle seals with them either. For whatever reason, rings seems to be exclusive to neck seals. It has nothing to do with whether the seal can be trimmed or not.
Your point about "micro tears" on edges is nonsense. It doesn't happen if you use a sharp blade. What can happen is "whiskers" where cuts don't meet properly, but they don't pose a tearing hazard and are easily removed. A nicked edge poses a definite tearing hazard, but there's no way to nick an edge if you trim it properly. It simply can't happen.
Stretching, however, does damage edges in the same manner that it damages the entire seal. That's where you get real micro tears.
You're entitled to your opinion and free to do whatever you choose with your own dry garments. Regardless, the Stohlquist instructions make it very clear why trimming is preferred and my personal experience in trimming seals for myself and many others backs it up. It works, the results are immediate and it doesn't adversely affect the life of the seal.
BTW, in the diving industry, where drysuits have been used for decades, trimming is standard practice.
What a ridiculous comment
Just think of how much hassle it would be and how much time it would waste trying to stretch 1000’s of seals to fit 100’s or 1000’s of individuals.