Another builder and I have been discussing the merits of thinning epoxy wrap coating. I was wondering what seems to be the consensus. Thin or not to thin.

Thoughts?

Why thin? You can apply epoxy thick or thin depending on the look you want. Simply using a stiffer brush will result in a thinner application of epoxy. Lite versions of epoxy help to that extent as well.

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If you read the literature - it is normally suggested to never thin thread finish, nor any other type of epoxy.

However, if one insists on thinning an epoxy, the thinning should be done very sparingly - on the order of a few drops of appropriate solvent.

If one thins epoxy - never ever use denatured alcohol. Alcohol is NOT a diluent or thinning agent to be used with any type of epoxy.

Rather, there are two appropriate solvents or diluent's to be used with epoxy.

#1 is Xylene. Xylene is a chemical that is part of the creation of Epoxy and is useful as a diluent or solvent. Again, if thinning an epoxy the amount of solvent used should be on the order of a few DROPS. Nothing more.

#2 is Acetone. Acetone is also a compatible agent to be used when thinning Epoxy - but it is not as an effective solvent or diluent for working with epoxy.

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If a person thinks that it is all right to use denatured alcohol as diluent - try this experiment. Have a small quantity of epoxy in a container. Then, place a few drops of alcohol in the container along with the epoxy. One will quickly realize that the alcohol does not combine with the epoxy, but rather - it remains as a separate entity in the container and thus does not change the consistency of the epoxy.

But, then, if one repeats the experiment with either Xylene (preferred) or Acetone - one finds that as soon as a few drops are added to the epoxy mixture, that the drops instantly disappear and become part of the original epoxy mixture.

A white paper on the use of diluents in epoxies: [www.sciencedirect.com]

Here are definitions of various diluents used in the industry. [books.google.com]

Here is a white paper on the use of Xylene and similar chemicals for very limited amounts to be used as a disuant agent with respect to an epoxy adhesive or finish: [www.lyondellbasell.com]

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Before considering the use of any chemical to be used as a diluent read and understand the aforementioned white papers so that you realize the ramifications of adding any material to an epoxy.

Read and understand before execution of any plan on these chemicals.

I’ve never thinned epoxy, don’t see the need to do it.
Norm

Roger -

If you want to do clear wraps then you need to thin the epoxy to accomplish that. Many use DNA mixed with epoxy to make it "water thin" for clear silk wraps. I have found that I get pretty good clear wraps using DNA. Set of the epoxy takes considerably longer and of course I do cover it with a couple coats of the ol' mil spec epoxy. Should (or could) we be using something else to thin the epoxy for creating those clear wraps instead?

On a little side note - Bamboo rods often have clear wraps done with spar varnish. I have never tried it but have often wondered if spar varnish was used for first coat to get a clear wrap, then letting that dry and then following it with a coat of epoxy would work.

Phil

If a thin coat of epoxy without anything else is not clear enough why would a coat of epoy over another coating be clearer?

Epoxy is going to yellow or amber over time. It's just the nature of the beast. Spar varnish tends to be a bit amber from the outset so you have the same issue.

The reason DNA is often used with epoxy to get clear wraps is that the DNA slows the set and cure time of the epoxy which allows the epoxy more time to fully penetrate and saturate the threads.

PermaGloss, used as is, will get you close to clear wraps on white nylon thread. I need to try it on silk to see if it will go all the way clear. If so, this would be your ticket. PG won't yellow, is rock hard yet flexible and will last for decades.

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When you thin the first coat and only the first coat, it is only for speed of application and nothing else. You can use acetone or DNA at a 1:15 ratio after the finish is fully mixed initially. This is only advantageous in high production situations where time is money. The thinner finish soaks in fast and levels. It allows the fast work flow of getting the threads saturated on move on to the next one. You should never thin the subsequent coats, just the first one.

For thin coats use Flex Coat Lite or, like Tom said, use a stiff brush and technique to achieve a thin coat or coats.

Flex Coat Company
Professional Rod Building Supplies
www.flexcoat.com

John,
Without a degree in chemistry, I will leave formulating epoxy recipes to those who do! They know what they are doing and we don’t. One might APPARENTLY get lucky thinning an epoxy but no one knows for certain what effect it has on the cured product without some type of professional analysis. Granted there are those who thin their epoxy with CLAIMED success and we aren’t building structural composites for NASA where NO variance is tolerated. Nonetheless, I personally see no need to thin epoxy in the first place = glob it on to insure thread penetration and tunnel-filling and wick-off what is not needed / wanted. If you are convinced a low viscosity (thin) epoxy is required, try CTS Crystal Coat. For the thinnest coating, although an urethane, try PG.
I was quite surprised to learn John Cates from Flex Coat condones thinning their epoxy, especially with DNA, and additionally at a whopping 1:15 ratio! I am not in a position to argue with him regarding the 1-to-1 mix ratio thread epoxies; I have much more experience with the (basically) 4-to-1 ratio structural epoxies in the composite industry. Is there a difference? Who knows?

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

I think what John stated means that after mixing at 1 to 1 add 1/15th the total volume of DNA. . Right, John?

I too have used DNA to thin epoxy when creating clear silk wraps. I have done it for years, very successfully! It does slow down the curing, however the penetration is thorough, which is hard to accomplish without thinning.

Michael, it is not that the epoxy is not clear enough! It is the fact that unthinned, it does not make the wrap transparent enough. Silk when thoroughly wet turns clear as the silk worm filaments are clear.

Mix the Flex Coat 1 to 1 normally. Once mixed, add the thinner at a 1 to 15 ratio, meaning for a 15cc mix of finish add 1cc of thinner. This will thin the finish enough to quickly soak in for fast production application. Many on this site aren't ever in a large production scenario so the advantages of thinning are moot. Again, it should only be done on the first coat only for speed of application, it does add considerable time to the curing process. I get it, its controversial, so if you want data then look at 40 plus years of our commercial customers that have done this process on countless thousands of rods and continue to do to this day.

Flex Coat Company
Professional Rod Building Supplies
www.flexcoat.com



Edited 2 time(s). Last edit at 02/15/2022 04:47PM by John Cates.

Thank you Mr. Cates; you are always a wealth of information and I am here to learn.

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Me too. My grammar and spelling are far from perfect.

Flex Coat Company
Professional Rod Building Supplies
www.flexcoat.com