Tom Kirkman Wrote:
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> Rod wrapping epoxies have been formulated to be
measured and mixed by volume. This greatly
simplifies the process and does not require the
purchase of any special equipment such as a scale.
I suppose you could call a pair of syringes
special equipment, but they're terribly
inexpensive and can be used over and over.

Exactly. In medicine, 3ml syringes are graded in 0.1ml increments, and 1ml syringes are graded in 0.01ml increments. If you can't get the two parts within 0.01mls of each other, get someone else to do it for you. But trying to weigh each part seems more like an exercise in futility if you ask me. And how is it done? Do you weigh two parts separately in two containers and mix them in the end? Adding one component from one container into another will result in leaving that little bit of material stuck to the container from one of those components, and theoretically imbalances the two. By much? Of course not, it's meaningless. Just as being off by a tenth of an ml using syringes is also meaningless.

As Tom mentioned, the epoxies have been formulated to be mixed by volume, usually 1:1. If you want to get crazy knowing the difference in densities of the two parts so you can weigh them, so be it. Just remember that in the end, you will still end up with two equal volumes....almost!

Ernie, I think the only way to progressively add epoxy to a pan on a scale to mix with weight as the criteria, is to add it from a syringe. Until the total weight gets to be what you have calculated that you need. Sort of ironic in light of the debate, isn't it? Make a calculation error and you're screwed. Using weight for measuring epoxy, in my opinion, is a complex solution to a problem that does not exist.

Ernie Blum Wrote:
>... But trying to weigh each part
> seems more like an exercise in futility if you ask
> me. And how is it done? Do you weigh two parts
> separately in two containers and mix them in the
> end? Adding one component from one container into
> another will result in leaving that little bit of
> material stuck to the container from one of those
> components, and theoretically imbalances the two.

(For the record...I measure with syringes)
But if I were to weigh epoxy it would go like this....
Put an empty cup on the scale and weigh....it weighs 1 gram.
Now put in resin...say 2 grams (scale will be at 3 grams).
Now put in hardener...2 grams (scale will be at 5 grams).

...come on Ernie!

Definitely some strange logic being applied in some of the posts in this thread. Wiping off excessive finish takes longer than applying 3 thin coats? That's head scratching.

Anyhow ...... for those that feel finish problems they're having, or may have had in the past, are a problem with incorrect finish mixtures? What kind of finish are you using? I ask because I've used three different brands of finish in either regular or high build, and have never once had a problem with an improper mixture. I've never used anything other than the syringes that either come with the finish, or with syringes available from a rod building supplier.

Even if you're trying to mix 1 ml of each part, syringes are pretty much fool proof. Why would you want to complicate the process by using weight, instead of volume.

Like Ernie said, small differences in volume are meaningless. Manufacturers build in a certain amount of leeway. We're not hand loading a hot load where a small difference in the amount of gun powder could cause a catastrophic failure. We're talking about applying finish to a thread wrap. Why complicate it?

This is getting a little silly and complicating and debating an easy procedure.

Just use a syringe. And use at least 1 cc per syringe, preferably 1.5 cc per each syringe, and you will be safely within the margin of error for the target of a 50/50 mix 100% of the time. I have never had a thread coat fail or not dry when using this approach. Yes, you may wind up with a bit of leftover epoxy. Big deal.

Why do you think typical adhesive epoxy containers have one plunger the pushes out the resin and catalyst from each side of the tube? If you push out enough you get close to a 50/50 mix, and the epoxy hardens. I make golf clubs which require bonding epoxy and I have never had a bond not harden due to a mix failure in the one plunger mechanism.

We don't use much epoxy on threads, so they put it in two different bottles.

How thick or thin you want your epoxy and how many coats you want to apply is your personal choice, and that's part of the decision making and the choices offered in DIY rod building.

A very experienced rod builder who produces rods in volume can use a high-build thread epoxy and get the job done in one coat. I'm not nearly that good and I don't have a high RPM rod turner and use my rod dryer to rotate the rod when applying epoxy. I wind up applying two or three coats of normal or low build depending on the size rod and thread I am using. Three thinner coats of a low build epoxy is fine, and I often do that, but it is NOT necessary or better. Lately I have been building fly rods from unsanded blanks, and I like three thinner coats, or at least a thinned first coat so it really soaks in well, as the ridges on the blank seem to make the initial soaking process a little bit more time consuming, so a first coat thinned with DNA or ISO sinks in better IMHO.

If you look at the Flex Coat video below they have simple pumps on the large bottles of epoxy, which you can buy. He pumps twice from one huge bottle and pumps twice again form the other bottle and makes the mix. A pump like that is not nearly 100% accurate (it is designed to output 1 cc), but it gets close enough to a 50/50 mix to make it work just fine. And he uses two pumps per bottle (2 cc) to ensure he is near a 50/50 ratio. Your mix ratio has to be quite a bit off for it not to work or dry. And his preference is two coats.

I suggest, if you want to obsess, do it about your thread wraps or something else, but not about unnecessarily complex ways to measure epoxy.


[www.youtube.com]

Chris Catignani Wrote:
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> (For the record...I measure with syringes)
But if I were to weigh epoxy it would go like
this....
Put an empty cup on the scale and weigh....it
weighs 1 gram.
Now put in resin...say 2 grams (scale will be at 3
grams).
Now put in hardener...2 grams (scale will be at 5
grams).

...come on Ernie!

Chris...Yes I understand that, and your math is dead on. Good job. It's the pouring of the materials that may be challenging. Doing it as you described, one needs to somehow be very precise in its execution. Wanting to "put in 2 grams" of one part or the other into an empty cup and hitting that 2 gram mark may be a challenge. So, let's say part one ends up being 2.4 grams. No problem. Now all you need to do is drip in 2.4 grams of part two and you're in. Damn...you dripped in 2.6 grams. No problem. Now all you need to do is pour in 0.2 grams of part one. Damn...you just dripped in 0.3 grams of part one. When you're up to a quart, let us know.

And of course...if you can be that precise in depositing product into a cup whereby the scenario described above does not occur, then all that measuring baloney is moot.

Yup, Ernie, that's how it can go. Unless syringes are used.

Exc it's a little easier since scales can go to zero with the empty cup on the scale. "Tare"

Ernie Blum Wrote:

> And of course...if you can be that precise in
> depositing product into a cup whereby the scenario
> described above does not occur, then all that
> measuring baloney is moot.

Touché Ernie...always the good sport.

I use to measure by squeezing out resin and hardener into a cup.
Then I would stand the resin and hardener bottles next to each other and making sure they were even.

As to weight exactitude: Who knows if the resin and catalyst are the same weight by volume? One is potentially lighter than the other.

david taylor Wrote:
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> As to weight exactitude: Who knows if the resin
> and catalyst are the same weight by volume? One
> is potentially lighter than the other.



They are not the same weight by volume.

..........

If you want to do weight mixing - which I do not recommend; it is easy enough to do.

First take two unopened bottles of part A and part B and weigh each bottle on a very good scale.

This ratio will then be your weight difference as measured by weight.

Just use this same ratio when measuring part A and part B by volume.

Tedious and unnecessary, but one can certainly do it if you wish.


Here is the ratio as stated by Flex coat on their thread finish.

--------------------------------------
Date: August 05, 2013 10:47AM

With the recent questions about mixing rod coating finish by weight, rather than volume - I sent an e-mail request to Flex Coat to request the correct mass weight ratio of mixing part A to part B by weight.

This was Craig's (from Flex coat) reply.

------------------------------------
The ratio is 1 part of Part A to .838 part of Part B. ie 10 grams of Part A to 8.38 grams of Part B. Hope this makes sense and helps you out.


Craig

----------------------------------------------------------------
So, you need to multiply your part B weights by .838 to mix the correct quantity of A and B of the flex coat finishing epoxy when using a scale to measure the quantities of mix.

-------------------------------------------------------------
If you want to measure other manufacturers epoxy finish by weight than volume; contact them for the correct mass weight ratio.

Take care
Roger

"This ratio will then be your weight difference as measured by weight." Assuming they were filled properly.

I say nice try, Roger. It all makes arithmetic sense, but there is no way that weighing can be less risky than syringes. Too many opportunities for error. Why anyone would go through all of that when syringes are so reliable, cheap, last so long, become caps for your epoxy bottles, is beyond me.

To me weighing is a risky solution without a problem.



Edited 1 time(s). Last edit at 03/28/2024 04:33PM by Michael Danek.

I certainly didn’t mean to create such a discussion on the attributes of volume versus weight.

As a career bench chemist, weight is much simpler and more accurate than volumes, that being said, the margin of error with these products is large enough that a syringe system is totally acceptable.

Sitting down at a cheap scale with catalyst and resin in Yorker, cap, bottles, and weighing into a shot glass is a simple rapid process.
Turn on the scale, tare (and zero) weight of the shot glass, add catalyst to the amount, desired, multiply that weight times 1.193, zero the weight of the shot glass with catalyst, now add the resin to the calculated amount using the Yorker squeeze bottle.

Now that is quicker and more accurate for me, but we all do things the way we feel best about the outcome. So syringe or scale, we all have a choice, whatever we choose and follow the methodology works.

Mike

Mike Hubbert Wrote:
-------------------------------------------------------
> I certainly didn’t mean to create such a
> discussion on the attributes of volume versus
> weight.
>
> As a career bench chemist, weight is much simpler
> and more accurate than volumes, that being said,
> the margin of error with these products is large
> enough that a syringe system is totally
> acceptable.
>
> Sitting down at a cheap scale with catalyst and
> resin in Yorker, cap, bottles, and weighing into a
> shot glass is a simple rapid process.
> Turn on the scale, tare (and zero) weight of the
> shot glass, add catalyst to the amount, desired,
> multiply that weight times 1.193, zero the weight
> of the shot glass with catalyst, now add the resin
> to the calculated amount using the Yorker squeeze
> bottle.
>
> Now that is quicker and more accurate for me, but
> we all do things the way we feel best about the
> outcome. So syringe or scale, we all have a
> choice, whatever we choose and follow the
> methodology works.
>
> Mike


MIke,

You do realize that the formulators of our epoxy thread wrap products have specifically formulated them to be measured by volume, not weight. This has required some "fillers" to make the 1:1 volume precise. This was done so that the consumer would not have to buy any additional equipment such as a scale, nor multiply anything as you mention above.

If the consumer wishes to measure by weight, the ratio will not be 1:1. Thus the manufacturers strove to make the process as easy and foolproof as possible. It is important to remember that the margin of error is not as large as many may think and the smaller the total batch the more critical the proper measurement is. Syringes are the least expensive and easiest way to achieve this, at least for the average consumer.

...........



Edited 1 time(s). Last edit at 03/29/2024 09:48AM by Tom Kirkman.

Mike Hubbert Wrote:
-------------------------------------------------------

> "As a career bench chemist, weight is much simpler
and more accurate than volumes...".

This may be true in general, but not in this case it isn't. In the example of the Flex Coat data, the weight ratio is 1:0.838. Great. Now let's say that you and I want to prepare 3mls total of combined mix. Flex Coat has already told me that all I need to do is combine equal volumes of their products to achieve the mix needed for it to set properly. You however don't trust this (I'm making this up!), and for "simplicity and accuracy's sake", are going to weigh your components with a ratio of 1:0.838.

I will use 3ml syringes marked in 0.1ml increments. You can use syringes if you prefer, but they will be unmarked. I want to keep you honest. Oh, and don't forget your scale. You'll need it to set up your cups, and then of course to painstakingly measure out weights in the proper ratio. The problem now is that, if you don't know the densities of the components, you cannot calculate ahead of time how much weight of each you will need, at the proper weight ratio, that will have you ending up with the 3mls or there about of the mixed product that you desired to have when you are done. Of course, you can easily find the densities of those components, knowing that Density = Mass/Volume. But look! You cannot escape that pesky volume parameter!

Here's what I am going to do. Because of what the manufacturers have done for us, I'm going to draw up 1.5mls of each component into their respective syringes, place each component into a mixing cup...and start mixing. Done. And here is the best part. If I did know the densities of the components, and I did the math involved in calculating how much weight of each component I would need to end up with 3mls of the mix, I STILL END UP WITH 3mls OF THE MIX in a 1:1 volume ratio.

Like Mike and Tom have suggested...it's like reverse engineering for a problem that doesn't exist.