Greetings.

As I was mixing my last batch of thread epoxy and fussing with air bubbles in the syringe I wondered if would be easier to measure out the epoxy by weight? With a small scale it seems that adding each part to a mixing dish would eliminate the whole syringe and air bubble issue. A little practice would be needed to get the right weight per milliliter, but that's easy enough to do.

Given the knowledge on this board, I'm sure it's been tried and thought I'd ask the question to avoid any pitfalls. Several searches have not found a discussion of that topic however.

Thanks for your thoughts. I've found this board to be a valued tool in my climb up the rod building learnng curve.

Give it the ole college try and get back to us. Seems reasonable enough of a thing to work.

The two parts are not the same density, therefore not the same weight, I think if you weigh each bottle you will see, not long ago someone posted here that his epoxy wouldn't set when weighing equal amounts.

There would definitely need to be some research as to the density of each, but it shouldn't be too hard. I'd start with separately weighing 3 ml of resin and 3 ml of hardener and recording those amounts. I feel that would be no less accurate than the sometimes messy syringe systems. I'm curious enough to give it a try and will report back my results.

Most of the mfg recommend measure by volume not weight. Not sure how you are getting bubbles in the syringe, I don't.

Bruce,
As the saying goes, it is elementary Watson.

All that you have to do is to take a pair of identical containers of part A and of part B - of the epoxy that you propose to weigh. i.e. the containers should be unopened containers - each of which are identical in size.

You will find that there is a weight difference. i.e. one part will be heavier or more dense than the other.

All that you have to do, is to put the weights in the form of a fraction and now you have the density difference and you now know what the difference in weight % wise of part a compared to part b.

So, now that you have the % difference you will always use that %amount of part a or b - depending on whether you are going with the greater or the lesser % of the part that you are mixing at one time.

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Lets make it simple.
Suppose that part a weighs 1 lb. Lets further suppose that part b weighs 2 lbs. So now, if you put 1/2 = you will have the ratio of 1/2 - so that 1/2 the weight of part A is to be used for one full weight for part B.

Simply insert the weight difference that you obtained by your measurements of equal containers of part a and part B and you will have the appropriate ratio to use all of the time with this particular product.

Having said that - what are you going to use to pick up an amount of part a and an amount of part b?

Are you going to use a spoon, a knife, a razor blade or what. Then, if you pick up a certain amount of weight with something - are you going to scrape off the remaining part a or part b off your picking up tool to avoid wasting material and if so, what do you use to wipe off the tool that you used to wipe off the measuring tool?

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The point that I am making is that if working with small amounts of material - using a weight method is much more complicated, subject to waste and aggravation that using the syringe method of equal volume as most commonly used.

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However, there are epoxies that use the weight method and do it very well by tools that are sold with the product to eliminate the issues that I have about cleaning tools etc.

Note:
For myself, I have never found that bubbles are a problem for myself. I simply mix equal parts of a and b as measured by a syringe and squeeze that amount into a mixing cup. I use a craft stick to mix for 120 seconds or 2 minutes to insure that the solution is well mixed.
Then, I go ahead and apply the finish - using a generous amount to be sure that I have enough material to completely saturate the thread and to also fill any tunnels or blank areas. I do this starting from the butt, up to the tip of the rod.
Then, I go back over the rod carefully inspecting each wrap and coating while holding a heat gun in one hand and a brush with finish in the other hand. As I do the close up inspection, I apply gentle heat to thin and to also remove any bubbles that may have popped up - and either dab off finish if too much, or add a dab on if there is not enough. Then, I go back a 3rd time, doing a very close inspection with magnification and a very bright light - to catch any tiny fault of any kind and correct it. On a typical rod, the entire finish application - to have it ready for the dryer is 5-10 minutes depending on the wraps, number of guides etc. You really are not using the brush to spread the finish, you are only using the brush to hold the finish and the rotating rod essentially pulls the finish off of the rod. No matter how it starts - by the end, the finish is smooth and free of bubbles and is turning on the dryer. If you chuck out rod building factolry tours and do a slow mo on the part of the video where they apply finish, the method thatt they use is quite similar t the method that I use. It simply works, and works very quickly.

Bruce,
Simply put, if an epoxy manufacturer (most rod building suppliers) stipulates measuring their product by volume, then measure by volume. If the (composite industry) stipulates measuring by weight, then measure by weight. It is as simple as that!!!

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

With all due respect, if weighing by weight were really that simple it would take only a few words to describe the process. Solve the bubble problem rather than introduce complexity that is IMHO sure to introduce error.

I invert my container of epoxy with the syringe inserted in it and wait for the bubbles to rise away from the syringe.

Why makes things difficult? The manufacturers have compounded these epoxies so that you measure by volume. That's about as easy as it gets.

Beyond that, equal weight of the resin and hardener will not be the correct mix. one is heavier than the other and thus you throw off the 50-50 volume mix if you measure by weight.

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Follow the instructions of the manufacturer, because if one has issues with the product the first question that is asked is “did you follow the manufacturer’s directions”.

If you want to experiment, that is OK but use scrap material so if or when the results don't work out you only lost some time and epoxy.

If you want to mix by weight then you have to determine the weight per unit of volume for each of the parts and calculate the weight ratio for each mixture also, you have to do this for every brand of epoxy you intend to use to insure consistency.


Have fun



Edited 1 time(s). Last edit at 11/21/2022 09:48AM by John DeMartini.

Bruce,

I think you have some great responses and Roger outlined solutions very well. I come to this with a career in Chemistry and also feel better working by weight.

As to bubbles, I alway put air with the syringe into the bottle as to keep positive pressure.

As to using weight, probably most of use make near the same size batch each time or small variations. When I open a new batch of epoxy I go by volume rating the scale with my empty cup, Tate again after part a with the proper volume, then add b at proper volume. Now I have my normal volume of an and weight, and you have B with weight and volume. So simple calculation for weight from then on. That is the way I do it, simple I don’t like volume as with the syringes are not very accurate.

Didn’t really add much

Mike

Syringes are 100%, absolutely, positively, perfectly accurate. They cannot be wrong. It is only the person drawing the epoxy into the syringes that might be less than accurate, This is why we suggest measuring at least 3ccs per part in the mix. This allows for a small margin for error on the part of the person doing the measurement. Being off 1 drop on a 1cc total mix is huge. Being off by 1 drop on a 6cc total mix is within the manufacturer's margin of error and will still provide good results.

Measuring by weight can be done, but it involves an increased risk of failure. Why people want to make things so much more difficult than they need to be is beyond me. It's not broke - why try to fix a problem that simply does not exist.

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Bottle inserts and syringes. Easiest and cleanest way possible. Tom is correct in saying "why make it difficult?" I do not go along with the 3cc rule however, Lol. Insert syringe into bottle, invert it withdraw a little finish, you will notice some bubbles at syringe end, slowly expel it back into the inverted bottle and the bubbles will rise out of your way. You can now withdraw finish without any air trapped in the syringe. Bob is then your uncle.



Edited 1 time(s). Last edit at 11/21/2022 09:42PM by Lynn Behler.

The finish manufacturers and suppliers have to allow for the average user, not the most proficient ones. If you were in their shoes, you'd indeed go along with the 3cc rule.

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You better do the 3 cc thing.

This subject has literally been discussed for DECADES. Hey if that is what you think should be done, go for it. In raising my 4 kids I tried to teach my kids so that they avoided what I did, but sometimes they just had to do it their way and then they would learn and then try to teach their children. Decades from now this subject will probably be discussed.

Hardly a question is asked around here ( unless it deals with specific blank info and such) that hasn't been answered in the past on this forum. Would people just look a bit at past posts, many wouldn't have to ask a question. There's a wealth of knowledge at our fingertips! A wonderful thing!!

Thanks everyone for your comments.

Bruce.

[flexcoat.com]

Simply put:
If you want to measure by volume - then measure by volume.
If you want to measure by weight - then measure by weight.

They both work just fine as long as you know the density of each of the products being weighed, and if you have equal size syringes if you measure by volume.

Be safe