To Mix by Weight or Volume?

How to make a Bow, a String or a Set of Arrows. Making equipment & tools for use in Traditional Archery and Bowhunting.

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greybeard
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To Mix by Weight or Volume?

#1 Post by greybeard » Sat Jun 13, 2020 3:43 pm

This topic has been raised previously [about 2011] regarding the measuring of the components of two pack epoxy glues.

Since then there may be quite a few new members that have not seen the post.

If you do not have access to scales that can weigh small amounts of materials accurately such as two pack glues the volume measure will work if you take some precautions.

I can’t find any old data sheets (Smooth-on) where they give details of the ratio mix by weight.
EA40Brochure.pdf
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In-accuracies in the volume measure will happen if you do not exclude or allow for the small air bubbles that tend to occur in the components when measuring them out.

I used 30ml as a measure because I use the 30ml disposable medicine measure, levelled off at the top to measure my two part epoxy.

One measure of each part is sufficient for me to glue up three core laminations and the back and belly glass.

The following details specifically refer to Smooth-on. Please correct me if my maths is a bit off.
Mix By Volume.jpg
Mix By Volume.jpg (35.39 KiB) Viewed 414 times
There a many excellent two pack epoxies on the market where the instructions state the mix by volume but make no mention of the air bubbles trapped in the components that can alter the ratio of mix.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Stickbow Hunter
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Re: To Mix by Weight or Volume?

#2 Post by Stickbow Hunter » Sat Jun 13, 2020 7:25 pm

G'day Daryl, I mix my Smooth-On by weight. Back in 1993 in a Smooth-On Technical Bulletin they gave the mix ratio by volume of equal proportions of Part A & B but also by weight; Part A: 100 - Part B: 83. I have always just measured it by weight.

Jeff

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greybeard
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Re: To Mix by Weight or Volume?

#3 Post by greybeard » Sun Jun 14, 2020 2:49 pm

Thank you Jeff,

My maths was not out by much, probably just the number of decimal places and rounding used during the calculations.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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