I apply Rain-X to all dry flies that leave my vise, if they don’t have CDC. I do the same with my yarn indicators. A simple drop of Rain-X dries completely in a few hours, leaving behind an unseen film of silicone that goes a long way to waterproofing materials for the river. I’m surprised more anglers don’t know about this. And no, Rain-X is not toxic after it dries.
A Very Effective Pre-Treatment
Decades ago, I learned about this novel use for Rain-X from a fly fishing message board. At the time, a product called Watershed was gaining popularity, but the mark-up was enough to attract the DIY nature of common anglers. (Watershed is still available and now distributed by Hareline.)
I immediately co-opted the small, yellow Rain-X bottle from my garage. It had a few ounces of the liquid left, and it spent the next five years on my tying desk before I finally needed a new one.
The results were excellent. Rain-X waterproofed my flies to the point where I often went without an onstream floatant. When a fly did wet out, it was easily renewed by squeezing out excess water with a cloth.
The pre-treatment lasted for a very long time, not just for a few hours, but for days of use. Once I applied the Rain-X to a fly, I never went back and did it again, and I considered the application nearly permanent.
These days, Rain-X remains part of my process. And as I watch anglers try every new floatant that hits the shelves, I simply don’t find a need to move away from what works for me: Rain-X at the tying desk and Aquel on the water. I also use desiccant powder for CDC and in times when I might want a dry fly to ride extra high. The only other floatant I carry is Payette Paste, which I like for greasing a sighter and occasionally dressing a yarn indy.
The Process
I’ve mentioned the Rain-X trick many times in Troutbitten podcasts and videos. And every time the question comes.
How do you use it?
Don’t make this complicated.
A single drop of Rain-X easily coats a few flies. You don’t need to soak them for any length of time, and you don’t need to dunk the flies completely. Just drip a touch of Rain-X on the flies (or on a yarn indicator) and work it in with your fingers. That last step is important, because you can feel all the fibers gaining the liquid and wetting out in your fingertips. Work it in for a few seconds, and move on. Let the Rain-X dry overnight, or at least for a few hours, until it’s fully dry.
Environmentally Sound?
When I mention Rain-X used this way, I’m occasionally reprimanded for using a product that is not environmentally safe.
But that is a misunderstanding of the process.
I use Rain-X as a pre-treatment, not as an onstream solution. Liquid Rain-X never makes it anywhere near the river.
Why does this matter?
Liquid Rain-X is indeed toxic, as listed by its own data sheet. It’s also highly flammable as a liquid and a vapor. So don’t lick your fingers after working it into the hackle of your Parachute Adams. And don’t play with fire around liquid Rain-X, kids.
However, when Rain-X dries, the carrier solvents of ethanol, isopropanol, and acetone evaporate away, leaving a thin film of silicone that cleverly waterproofs the materials of your fly.
I’ve been asked about this so often that I looked into it deeply. If you’d like to do the same, here are resources:
Here’s the Safety Data Sheet for Original Rain-X
The dried Rain-X film is known as a Polydimethylsiloxane (PDMS), and carries no toxicity. When a PDMS eventually breaks down, it does so into the naturally occurring substances of a river, like silica, water and carbon dioxide.
More on that in the research document HERE.
So, there ya go. Use Rain-X as a pre-treatment and love your life.
Fish hard, friends.
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Enjoy the day.
Domenick Swentosky
T R O U T B I T T E N
domenick@troutbitten.com
Do you use it on foam terrestrials? thank you!
I do! And it works great! I think you are safe to use it on anything but CDC flies. For CDC just use a shake and float of some sort and you are good to go!
Same as Bryan. I use it foam as well.
Thanks for the tip, I’ll give this a shot. Do you happen to know if this is the same product as flyagra?
I happened to find a full bottle of flyagra on the river last year, but it’s quite expensive for a small bottle. Maybe this is a better, and slightly cheaper, alternative?
No. Flyagra is not a pre-treatment. It’s for applying on the stream. Rain-X only works when you apply it the day before and allow it to dry fully.
Thanks ..Great article.
Cheers.
This is why we’re all here.. Thanks for doing God’s work Dom..
Ha. No problem. Thanks for your support.
I’ve used rain x for years, agree with everything you’ve said. You mentioned cdc flies. I generally don’t use it for those, I use cdc oil and powdered floatant to avoid losing the natural oils of the feathers. Do you use on your cdc flies as well? Thanks for all the awesome content!
Thanks very much. Correct, I do not use Rain-X on my CDC flies. I only use dessicant powder for CDC.
Really interesting idea, and I can see why it works so well. I’ve been reading Troutbitten for a long time and always appreciate the practical approach you take.
I’ve also spent a fair bit of time working with hazardous chemicals, so I tend to look at these things through that lens as well. I might be overthinking it, but I’d be a little cautious about the ‘not toxic after drying’ point.
The SDS for Rain-X still classifies the product as hazardous and notes toxicity to aquatic life, mainly due to the solvent system. While those solvents do evaporate, it’s not always straightforward to assume the remaining film is completely environmentally neutral in real-world use, especially with repeated wetting and abrasion.
On the PDMS side, most of what I’ve seen suggests low acute toxicity rather than no toxicity, along with persistence and sediment binding. That feels slightly different from how it’s framed here.
I’m not against using it at all, and I get the appeal of a simple, effective solution like this. Just thought it might be worth adding a bit of nuance to the environmental side of things.
I’m also not sure there’s a perfect alternative here either. Even things like silica-based desiccants have their own considerations, so it’s probably more a case of trade-offs than a completely clean option.
Hi Steve. With your background, I can understand your caution and skepticism. Did you read the link above? The research shows there’s nothing hazardous, once the carrier solvents evaporate. If you have research that shows otherwise, email me.
Cheers.
Dom
I am glad to see you have gone over this topic again. When I first heard you mention it a few years back, I decided to give it a try. It’s the best tip I have learned to keep dries floating longer without having to re-apply floatant over and over. Thanks Dom!
Nice. Glad to hear that.
Sounds like a great idea. Floating my flies has been one consistent frustration. They all start sinking after a while
This will help, Don. But it all begins with a well-tied fly too.
Cheers.
Dom
Dom, You go boy! I loved your article on RainX!
Keep up the great article.
Sal Serbin
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Just bit the bullet and did this on all my dry flies…I have too many flies.
I’ve been using spray Scotchgard Fabric Water Shield as a pretreatment on all the dry flies I have tied or purchased for a while. It also seems to work well. It’s been very rare, if ever, that I felt the need to re-treat a fly after multiple uses. Have you tried that product? Do you know if it has similar ingredients and non-toxic properties to Rain-X?
Sorry. I don’t know anything about Scotchgard. Cheers.