The subject of whether or not to thin epoxy thread coatings rears its head here quite often. Being a very busy public forum that requires quick answers to immediately pressing questions, most answers are usually somewhat brief in nature, although a great deal of help can be garnered from them. But they are not going to be the sort of treatise you’d see in something like RodMaker.

In an effort to be fair on this public forum, let me say that although myself and several others here consistently warn against thinning of epoxy finishes with solvents, some do it and many of them get excellent results. For example, Roger Seiders of Flex Coat supplies more epoxy finish to the custom rod building craft than any other epoxy supplier. He also sells more epoxy thread finish to the commercial manufacturers than anyone else and nearly all those commercial makers, including the makers of some of the very highest end rods, do thin their finish per his instructions. They get good results or they wouldn’t do it.

Typically, they thin their finish because they’re in a situation where they must be able to easily manage the epoxy and have enough pot life to finish quite a few rods per batch of finish. Roger has actually spent personal time with many of them, instructing them on how to mix, thin and apply Flex Coat. So yes, you can thin epoxy finish without doing harm to the finish and yes, you can get excellent results as well. But as in so many things, you have to follow a certain procedure and understand what you’re doing, and why, or you can just as easily foul up your next finish job.

Generally, as far as most custom rod builders go, I have never seen the need to thin epoxy. A few years back, Roger took a look at one of my rods, finished with Flex Coat in fact, and remarked that it was as good a finish job as he had ever seen. Ralph O’Quinn was standing next to him at the time and made nearly the same comment. But the finish on that rod had not been thinned nor heated. My take continues to be, that most custom rod builders needn’t thin their finish and when they do, if they aren’t aware of some caveats, they can very easily ruin their finish. If the finish gels or sets before the solvent has escaped, you will have a problem. If you over-thin the epoxy with a solvent, you will have a problem. If you thin with the wrong solvent, you will have a problem. In other words, there are few ways to do it and have it work, but many more ways to do it and have everything go bad.

So, if for some reason you still feel the need to thin your epoxy, my recommendation is to contact the company that supplied the finish you’re using and ask them specifically what they recommend for doing so and how. If you use Flex Coat epoxy and want to know about thinning it, visit their website and follow their instructions. Then if you have a problem, you know where to turn. If you use U-40, or ThreadMaster, or Amtak, or whatever else is out there, and you wish to thin in, contact the company and get their recommendation. If you have a problem, you know where to return and complain.

Suffice to say that you can thin epoxy without harming it or ruining your finish job. But, in the case of most custom rod builders it’s usually possible to achieve the same desired end without doing so. However, if you wish to do it, talk to the company that supplied your finish and get their recommendation. They sell the product and they want you to get good results with it. They won’t put you on a procedure that will cause you to have problems. You do, of course, need to listen to what they tell you and follow their instructions to the letter. Of course, we always do that, don’t we?


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I always thinned my Flex Coat with about 7-8 drops of acetone per 15 cc of total mix.....but was always afraid to admit it here on the forum, in fear of the utter bashing it would receive from others. As I recall, I never had a problem and actually thought I had a better first coat penetration than I would've if I used straight high build.

Mike

NERB that types with a bar of Ivory soap in his mouth.

Hi Mike,

Bashing isn't always a bad thing. Sometimes, discussions such as this topic make for a highly interesting read while providing excellent information. To that end, I'm glad it came up, and wouldn't have issue with it appearing again in the furture. While I don't thin my finishes using acetone or any other thinning agent, I also don't have a problem with those who do.

If it works for you and others, then go for it. It is just that chemicals such as acetone, being toxic, have come under fire, sometimes rightly so. I use to use it almost exclusively to clean my blanks after component assembly, and have even used it to wipe of epoxy from my hands. As I've gotten older in my life, I've experienced affects that do lead me to believe acetone may have played a part. I just don't know what environment within a shop or home, would be necessary to effectively and safely apply it.

Having said that, I personally prefer less possibly harmful means to build my rods. I substitute Isopril alcohol to do most of my cleaning and only us acetone when absolutely necessary. Beyond that, I have always employed techniques to accomplish a thinner finish. And I guess I'm within that school of thought that I don't feel I need to employ those kinds of measures such as what a commercial organization might employ.

Patrick...the best topics are those that provoke arguement IMHO, and the thinning of finish has always been one that I've avoided like the plague. I used to thin Flex Coat with acetone, and it worked for me. When I started reading this board a few years ago, which I of see as an updated "book" to the rodbuilding books I learned from, I've since changed my "thinning ways" reluctantly, due to what I read here. Toms post is almost like a free pass to thin certain finishes, but not all as stated....consult the manufacterer before thinning.

I'm really glad you mentioned the harmful effects of acetone and throw in thoughts of a safe working environment. I've been employed in the environmental clean up industry for close to 20 yrs and have been exposed to more than you could imagine with the exception of radiation (I think). Shop safety isn't all about safety glasses.

Now we need a bunch of posts about molecular degradation of the amines due to influxuary biticulation of the mass (solids) combined with thermal attitude......etc

I'm just the opposite of Mike on this one. Built rods since 1981 and the last rod I built was the first time I've ever thinned my finish. I knew I'd have to try it some day... Worked fine and I did like the bit of extra working time that I had. Will I do it from now on? Dunno.

Putter
Williston, ND

About 3 days ago I was going to finish a butt wrap and 2 guides on the butt section of a spinning rod. My Flex Coat High Build had started to crystallize or settle into the bottom so I nuked it a little, probably 7 seconds. I thought it was too hot to use , it was warmer than body temp so I ran cold water over it for a few minutes to cool it down before use. I got a good mix, poured it out on my little foil dish , blowed out a few tiny bubbles with a straw and began applying using a brush.
It went on so thin , I thought I was going to have to use two coats although I managed with one. That being said, why wouldn't it do just as well to heat the resin a little before mixing instead of thinning it ? I have never seen High Build this thin before . And I never use it under 70 deg. ambient.

I have been building rods for a long time, and I always thin my finish, with a very simple reason, my first coat is extreme thin, I barely cover the threads, with a very thin finish, thinned with Acetone, the reason why I do so, is , my second coat will distribute a lot better over the Ups and Down from the thread art, as I shown already in many pictures, you can lay a ruler on top of my finish and it is absolutely level. I think Doc Ski uses the same methode.
I thinned every available finish Classic coat, Flex coat, Thread master etc.
Best Regards Mark Crouse _ The Munich Rod man

If you need a thinner finish try the Diamondite from Swifty,Goes on thin.about twice a thick as water and has a work time that you can speed up if you finish sooner.I never thinned finish and never felt I had to.I actually had a tuff time with the Swifty but after a few got used to it.

Freddwhy (Rapt-Ryte)

Michael,

We don't allow bashing on this site. I don't believe anyone has ever been "bashed" because they advocated thinning an epoxy.

For the record, I do not recommend thinning epoxy with a solvent. I see no need for it in terms of what most custom rod builders need from their epoxy for the number of rods they finish at one time. And, I get emails every week from guys who do thin their epoxy and often have terrible results stemming from what they thin with and how.

The point I made above is only that it is possible to thin an epoxy thread coating without automatically ruining the epoxy or creating inherent problems. But I also said that for every success there is a failure waiting in the wings if you don't understand what you're doing. This is why I suggested that if you are dead set on thinning your epoxy, consult the epoxy supplier and get their recommendation/instructions for doing so. Some are going to tell you not to do it under any circumstance. Others will tell you it's okay and even tell you how to go about it. But do consult with them first.

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The first couple rods I did I thinned my epoxy with either acetone or denatured alcohol. I don't remember which. I had been told by another builder that that was the way it was done. Both of those rods developed all kinds of cracking and checking of the epoxy finish on the wraps in about three months time. Really looked bad. Maybe it was thinning that did it or maybe it was something else. All I know is that I stopped thinning it and just went to a 'lite' finish and the problem has not returned. I don't have the nerve to ever thin my epoxy again.

I used to patronize a tackle shop where the owner repaired and built a few rods. I was there one day talking to him and watched him mix some epoxy. He added some sort of solvent to it and then started applying it to the wraps. Just as he finished up, he took out a propane torch and fired it up. I started backing away and asked him if he thought it was wise to put a flame to something that had a flammable solvent in it. He said he'd been doing it for years. When the flame hit the first wrap there was a sudden !!!WHOOOOOF!!! and a puff of bright flame. It didn't faze him and he went right on to the next wrap where it happened again. The rod looked okay and I guess that was how he did all of them.

I've never thinned my finish and see no need to do it. But if I did, one thing I wouldn't do is put any sort of flame to it. You guys who like to flame your finishes might keep that in mind if you're thinking about thinning your epoxy.