Hi All,

This is a follow up from my earlier post about epoxy drying times [rodbuilding.org]

This morning I checked the rod again, and no change to the epoxy. It is soft enough and thin enough that my finger nail can actually mark the thread with enough pressure.

I also checked the left over epoxy on the foil, and it has set perfectly, hard and glassy like it should be. I find this strange, as the left over epoxy is about 3-5 mm thick in blobs, and the epoxy on the thread is so thin.

I would have expected the thread epoxy to dry and set quicker than the left over blob epoxy!

I can now only suspect that 24 hrs drying time for the CP was not enough and there is still some moisture in the thread. Other than that I believe that I have done every thing perfectly based on how the left over epoxy cured perfectly!

I am still baffled!!


Thanks,

Richard



Edited 2 time(s). Last edit at 08/29/2010 09:32PM by Richard Khoury.

The thickness of the epoxy has little to do with the curing as it is not an evaporati8ve process ( it does not "dry"). In fact a larger mass often cures faster. Being able to mark through a thin coat of the flexible epoxy does not surprise me, as the epoxy used for wraps is meant to remain flexible.

What you may be seeking, "hard as nails" is better achieved with something like Perma Gloss.

Hi Phil,

I am not necessarily after a rock hard finish, I just presumed that this is the norm.

I have always been under the impression, that a harder finish will protect the binding better, against scratching and general wear and tear.

I am more worried that if my finger nail can mark the epoxy easily, then rocks, branches, etc with do much more damage.

Overall I have no problems with the finish aesthetically, it's the structural finish that I am concerned with.

Thanks,

Richard

If your epoxy is mixed with the correct proportions it should harden to a state where normal usage will not scratch or abraid the finish. Rod wrap epoxy is designed to remain somewhat flexible, though not "soft", so that it does not crack when the rod is flexed.

Mixing very small portions makes having exact measurements critical! With 1 cc of each, a droplet might throw off the balance.

It may be the CP, but usually moisture causes some milkiness that is visable.

Epoxy cures by chemical reaction, not evaporation, so the thickness of the coating has nothing to do with drying time. It does, however, have a lot to do with how hard you perceive it to be.

The thin coating over your wraps will no doubt be dented by the pressure you're exerting with your fingernail. I'd suggest not doing that. Nothing is wrong with your epoxy.

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

If you will check other rods you have from years ago I think you will also find that enough pressure from a thumbnail will dent them to. Thats a lot of pressure. If the stuff in your mixing cup is OK then the stuff on your wraps is OK. I find it that finish is OK to be used in three or four days but can take up to a month to achieve its final hardness.

Richard,
One difference happens when you have thin epoxy - as is the case for your rod, and thick epoxy - as is the case for your left over epoxy.

The difference is HEAT.

When you have a very thin layer of epoxy, the layer of epoxy is so thin that there is little self heat generated as a result of the "kick" or cure of the epoxy.

But, in areas of thicker or the leftover epoxy, the epoxy will self heat and increase the actual temperature of the epoxy by a little or a lot.

i.e. as the thin layer /layers of epoxy were curing on the epoxy, it had to rely pretty much on the heat in the drying area to either aid or inhibit the curing process.

But, in the case of the thicker amount of left over epoxy, the self heat generated as a result of the thickness increased the temperature of the epoxy and helped it to "kick" or to enhance the cure.

I would simply suggest that you mix up another, more generous batch of epoxy - to be sure that you have equal proportions of both parts a and parts b.

Then slowly mix the epoxy for at least 120 seconds, frequently scraping the side of the mixing cup as well as the mixing stick, to insure that 100% of the contents of the epoxy mixing cup are being 100% mixed.
Then, apply another coat of epoxy to your wraps, perhaps a bit thicker than you normally use.


Insure that all bubbles are out of the finish on the rod and let it turn for 24 hours drying.

Then, let the finish cure - in a warm location for a week and retest the finish. I am guessing that you will find that you now have a rock hard finish.

I find that for even a pretty thin finish on the rod, that after a week, it is nearly impossible to dent the finish with your fingernail of the cured finish on your rod.

My guess is that you either had unequal amounts of mix in your actual mixture that was placed on your rod, or the mix was not mixed well enough to get a good cure with the available heat.

p.s.
To help things out, especially in the heat of summer, it is not a bad idea to leave the rods, after they have had the initial 24 hour setup to set out in the sun for a couple of days. The direct rays of the sun can really help on the final cure and hardning of the finish.

That is also why many folks use ovens around their dryer which are t ypically kept at a temp of 90-110 degrees. This heat really helps to uniform and cure the epoxy as the rod is drying.

Although I don't use an oven when finishing a rod, I do have a separate heater and thermostat in the shop. So, when I am drying a batch of rods, I turn the heat up in the shop to 90 degrees for the duration of the drying so the extra heat helps to accelerate and finilaze the cure.


Good luck
Roger

I have a question are you applying your finish on a turning rod? May I suggest that thee next time you apply finish do it in quarters without the rod turning. Put a thine coat on top, do a 1/4 turn apply another thin coat, do this tell have come around 360% now look at the bottom of the wrap and wick off the little globs to the low areas, turn the rod 180% and repeat. Now 1/4 turn the rod and repeat, next turn the rod 180% and look for globs or low spots. If there are low spots move some finish over. You can do 8 to 10 guides before the finish starts to gum up. Now turn on the drying motor you should have a nice even finish, no globs or foot balls

Good Wraps Bob

Hi All,

Thanks again for the explanations, I now have a better understanding of how epoxy works.

Bob, I am hand wrapping each section at a time, and then putting them on the turner to dry.


Kind Regards,

Richard

By hand wrapping I take it to mean, you apply your finish with out the rod turning in the dryer

Good Wraps Bob

Richard, I used to have the same worry as you .. the left over finish curing hard and the one on the rods just always seem to be 'soft' enough to imprint with the fingernail.. was even more worried when i was able to peel the finish off, instead of cracking which you get with the store bought rods..

after using the rods, and understanding some of the replies, i have gotten over it.. it holds up fine... have landed 10~ 25pound catfishes with no ill effect..

-
Give a man a fish, he'll eat for a day..
Teach a man to fish, he'll be broke!

The finish on the wraps and the finish in the mixing cup is the same hardness. You perceive the finish on the wraps to be less hard because it's a thinner coating.

Take some sheet steel material, one in a thin sheet about the thickness of a piece of paper. You can dent that with a thumbnail too. Now take another sheet of steel in a 1/4 inch thick sheet. Your thumbnail won't be able to dent that one. But they're both the same hardness.

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

Food for thought, take a old blank, put a 1 inch or longer wrap on it. Take 1/2 the wrap and coat it with CP. Now apply a finish to it. Extend the finish about an inch on to the blank. . Let this cure and dry . Now check to see how hard the finish is on the wrap and on the blank. What I perceive, there is 3 differences. The under lament. If you use CP the finish does not penetrate into the thread it just lays on top (finish soft), (No CP finish is harder). What you may also try is putting 2 or 3 coats of CP just on the blank once dried cover it with finish. You will also notice a difference. So what you maybe be feeling is the cushion action of the thread or the CP. Just a thought that was not explained vary well explained

Good Wraps Bob