On my last build, when I put on the final coat over a tiger wrap, I did an experiment. I wanted only a small batch, so I weighed it. 1.5 grams each, resin and harder. I have a very accurate small scale, recently checked against calibration weights, so I believe the scale It looked ok, but was still a bit tacky after 24 hours. After weighing the individual components, the hardener is about 14% lighter than an equal volume of resin. Is this enough to make a difference?

It most certainly is and the less you mix the greater the difference by percentage. The two parts don't weigh the same per volume. Don't do that - it'll land you in trouble. Measure by volume. Epoxy is cheap. Your time isn't.

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You can take that 14% and do the math but why? Syringes work fine I mix .5 of each without issue.

Freddwhy (Rapt-Ryte)

Thanks gents. Tom; point taken about what's cheap and what isn't. It was an experiment. I know my little scale is more accurate than eyeballing a measuring cup, so I will be doing more experimenting, doing the math as Fred suggested. I don't have syringes, but I will have to aquire a supply if i can't get the scale to work. I won't be applying any weighed mixes to actual builds until I get it worked out.

The syringes are also cheep And will last years

Bill - willierods.com

Gary,
In many industries, epoxy mix ratios are mixed by both volume as well as weight.

Each work equally well, as long as the correct weight ratio is used and or the correct volume ratio.

The vast majority of the epoxies used for Rod Building finish work employ a 1:1 mix ratio.

However, as you discovered there is a 14% difference by weight for the particular epoxy that you used. If you used the 14% weight difference and mixed that particular epoxy, the mix would be equally good.

However, if yo used a different epoxy, you would need to verify any weight difference, if you chose to use weight to measure rather than volume as many epoxies are generally measured.

Any time you have an issue like this, you can contact the epoxy manufacturer, and get the both the correct mix ratio by both volume and by weight.

Good luck

The syringes are just so easy that anything else is almost like making extra work for yourself for no real benefit.

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A set of syringes costs less than $3.00 and will last for years. If used properly, they eliminate the issue of measure balancing completely! Additionally, their use is fast and clean.

In short from my perspective.....the only way to go !!

I just ordered parts for my next build. I will call them and see if they can Add some syringes to the order.

I've been doing process control design / engineering / programming for almost three decades. Looks like the nerd in me is trying to sneak out of work and into my hobby. LOL thanks guys for putting him in his place.

Gary,
Your post is perfectly reasonable.

As I said earlier, there are lots of industries that only use weight to measure out parts of epoxy for mixing.

Good luck

One suggestion: get the pumps (like the ones in a liquid hand soap bottle) that fit in (and made for) the epoxy bottles! these work great, stay cleaner than syringes, and seem to be accurate. cost a few bucks. Mudhole. Your idea of using weight adjusted for density is a good one though. That will be most accurate for measuring, if you get the ratios right.

My suggestion is to get the inserts that fit the finish bottles for the syringes.
Ricky

I go even easier. I use a stainless 1/2 teaspoon measuring spoon. Poor it level with Part A, scrape out all into cup, then Part B the same way. The residual in the spoon (very little) guarantees an ever so slight less amount of Part B. I have the big bottles of finish about two thirds gone now, and they are within about a 1/16 of an inch of eich other. It doesn't get much simpler than that.

Dony,
I read and understand your post about using spoons.
However, the issue that I have with spoons is the fact that you need to clean them and basically waste the finish that has been left on the spoon.

But with the use of syringes ,and in particular, if you leave them in the bottle cap, you never have to clean the syringes, and you waste no finish.

Be safe

Spoons are NOT easier than syringes, for the reasons Roger points out, plus the ability to use different size measurements depending upon the size of the project! I do use spoons for the epoxy paste adhesives, however the measurements are not nearly as critical for adhesives as it is for coating epoxies.

Seems the syringes are the quickest and most accurate way

Bill - willierods.com

Aftco is the only 2 part finish that the manufacture states you can use a scale to measure with. It works I do it all the time.

Just a note on syringes...don't use pharmacy syringes as they have silicon on them as a lubricant and silicon will contaminate the epoxy and cause small pock marks in the finish. Thanks Barry

each builder has there own way of doing anything on a rod
Whatever works for each Go for it

Bill - willierods.com

I found that using the syringes was faster than weighing .The syringes stay in the bottle all the time .(no cleaning & avoid the problem of putting the wrong syringe in the bottle ) & all I do is tip the bottle upside down & draw down on the syringe until the level sits on the line for the amount I use (usually 3 ml from each bottle.When finished they go back onto the holder that I made with the syringes still in upside down .I have been using that method for a number of years now with zero problems .The only problem I have ever experienced was when I was using the eyeball method .

Regards Baz

Bundeena
NSW Australia



Edited 1 time(s). Last edit at 03/22/2015 06:33PM by Barry Chapman.