Through my composite experience, I am aware that virtually all epoxies will eventually yellow, some more than others. Whether in the cured state or still liquid in the bottle/can, this can be most commonly due to oxidation or UV factors. In my five years of rod building, I have experienced yellowing, even browning, of the thread finish hardener while still in the bottle, but not to an excessive, unusable degree. However, with the last kit of ProKote regular I purchased about four months ago, the hardener was considerably darker than my remaining ProKote hardener which is two-three years old. The unopened, new hardener, which has been stored in a cardboard box, has continued to darken to the point it has become a dark purplish-brown; so dark in fact that I would be uncomfortable using it for thread wraps. I did not get around to returning it but should have (old stock?).
My questions are; 1.) Have any of you experienced similar? 2.) Why would one bottle of hardener darken immensely more than previous others of the same brand?
I am not picking on ProKote; it has always performed reliably and adequately since I started wrapping rods. This situation is new to me.
Please view the attached photos if you care to do so. The third/last photo shows the color comparison between the old and new hardener.
[www.rodbuilding.org]
[www.rodbuilding.org]
[www.rodbuilding.org]
Thank you for taking the time to explain and teach me.

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

They're all going to turn - in the bottle or on the rod.

..............

Tom,
Thank you for the reply. While I have experienced and agree with you that all epoxy hardeners will eventually “turn” as you stated, I am concerned with why this new bottle has turned immensely darker over a considerably shorter period of time than any of the previous bottles of the same brand hardener. Did you get an opportunity to view the comparison photo? Although I was not fortunate enough to meet or converse with Ralph O’Quinn, none the less I miss him!

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

The "new" bottle, may have been sitting on the dealer's shelf for some time. Or... it could have been at the manufacturer's/re-bottler's warehouse for longer than normal.

................

Thanks again, Tom. I suspect you may be correct in that it was simply old stock. But it must have been extremely old stock if that much darker (and noticeably darkening further each week) than my present 2-3 year old on-hand supply. That is what has me baffled. Once again, I should have immediately returned it. I am still interested in other’s experiences, ideas and comments. Please offer your opinions, thoughts and reasoning.

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

My experience with any epoxy is it is fairly stable given proper and stable storage conditions and changes tend to be gradual. If it is exposed to extremes all kinds of odd things can happen. You say you bought this batch about four months ago. Would of put your shipping time right in the middle of winter. Even if your in a warm climate where did it ship through and how long did it sit somewhere in below freezing temps? Is this problem don't know but my experience again is extremes and epoxy are not a good combo. I would see what prokote has to say about exposure to extreme temps and if it has a shelf life. There are some epoxies that say say don't use after being open for certain period of time. Temp extremes could cause expansion and contraction causing a poor seal of the bottle.

Have you contacted them and asked if anything changed?

Mark,
You have a non issue.

You have a product that doesn't suit you. Pitch it into the nearest garbage can, purchase a new batch of what ever brand thread coating that you prefer and move on.

Over the years, I have done this fairly often. But, I also try to forecast my future rod builds and prefer to purchase thread coatings in batches that match my available forecast for builds and repairs down the road.

---
On a similar vein, I carefully check the date of manufacture of any lead acid batteries for my vehicles or my boat. I do my best to purchase lead acid batteries that have been manufactured in no older than the previous 30 days. No point in having a battery age while sitting on a distributors shelves.

I haven't checked recently if there is date code of manufacture on finish bottles or not. But, if so, try to purchase only freshly manufactured containers of finish.

Take care

Mark, it kinda makes you think about using a one part finish..

There is a possibility that the manufacturer of the resin made a bad batch. I work in Chemical plants that make polymers and resins and have seen operators mess up batches in production. If the lab considers the batch to be within a certain tolerance they will let it be distributed. Typically these types of epoxy resin are made in small batches where the margin for error is greater. Also because of this the same reactors, vessels and piping may also be used for other similar chemical service and the equipment will need to be cleaned out between each different service. Operators that continue to mess up are usually promoted out of operations or put into plant safety.

Thank you to all who took the time to reply.
Michael, I live in So Cal but do not know how cold the UPS trucks were delivering my order. While I cannot be certain, it may be unlikely excessive cold caused my issue. But then, my previous oxidation and/or UV contamination observations can almost be ruled-out as well.
Billy, I wanted to learn more unbiased opinions before contacting ProKote.
Roger, you are correct on all counts. I purchased this new batch in a smaller size because I was still using the old batch after 2-3- years and it was getting darker than I preferred. While your thinking parallels mine quite often, I am too much of a cheap bastard to toss it into the garbage.
Ben, one-part finishes have their pros and cons as well. Most so-called one-part finishes (commonly urethanes such as PG) actually use the moisture in the air as the catalyst/hardener to cure. This also equates to moisture getting into the bottle when opened and prematurely starting the curing process with the remaining material. I have used PG a few times on UL thread wraps with nice results but to achieve the desired, thick coat on my salt builds would take too many coats = too much time. I typically stick with epoxies specifically designed for thread wraps.
Lance, with this one bottle being so different than all the previous ones, I suspect you may be correct in the final analysis. Meadow muffins happen and budget restraints can possibly dictate overriding QC.
So, with the information gained by those generous to reply here, I will contact ProKote to learn from what they have to offer.
Thanks again and stay healthy, wealthy and wise!

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

Likely a bad batch.

Trash it and get ThreadMaster or Hitena. They both seem to yellow less than other finishes I have tried, and cure in a reasonable amount of time. They also seem to me to have less problems with crystallization. As soon as it comes back into stock, I want to try the Gen4 epoxy, which sounds quite nice and worth a try.
Norm

Lynn, I am leaning in that direction as well.
Norman, I certainly cannot argue. I have already tried ThreadMaster, but the light version while I know you prefer the regular. While it has yellowed a bit in the last few months, it appears to be much less than any other finish I have tested with the exception of CTS Crystal Coat; I have not tried Hitena. I have witnessed talk of the Gen4 and am curious to its performance; please keep me posted on your veteran, trusted findings and opinion.
For the time being, I am pleased with the overall performance of TM Light and will try the regular version soon. While it may presently be my go-to thread finish, I resist hiding my head in the sand or putting blinders on. All of the present thread finishes are very good products and are basically variations on the same theme; it requires testing to discover the one best suited to each one’s personal preference, desires and requirements.

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

Mark, you should try the regular Threadmaster, it is my daily go-to epoxy. The pot life is not as long as the Lite you have used, but then again, most lite versions are all longer then their regular versions. Maybe an additive?
The one epoxy that does not get mentioned much, is Classic Coat. I tried it and found it to be quite good, in pot life, clarity, bubble clearing and leveling. Do not know yet the UV effects.

Afetr using CTS Crystal Coat on a number of builds, I now use it rarely on my ultra premium builds that have time to wait and will pay my upcharge.