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Author Topic: Measuring Epoxy  (Read 1921 times)

Offline Tim Wescott

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Measuring Epoxy
« on: February 13, 2013, 02:31:45 PM »
Brodak 30-minute epoxy resin is a different density than Brodak 30-minute hardener!!  I've been measuring larger amounts by weight rather than trying to estimate volumes, and wondering why I seem to persistently have more resin than hardener.  I just weighed each bottle -- there's a 20% weight difference with only a slightly different amount of epoxy in each.

I can cope.  But before you assume that equal weight implies equal volume -- check.
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Offline MarcusCordeiro

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Re: Measuring Epoxy
« Reply #1 on: February 13, 2013, 05:43:41 PM »
When I used to be an aircraft mechanic, the guys from the "epoxi" area weighted every mix they did, be it epoxi glue, resin or sealant, but according to the maintenance manual.
Just a reminder, the instructions say equal parts, meaning equal volumes, not equal weigh.
Anyway, good advice.

Marcus
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Offline RandySmith

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Re: Measuring Epoxy
« Reply #2 on: February 14, 2013, 10:25:32 PM »
Most epoxies are to be measured by equal parts, however a few specs call for equal weight, best to check which...

Regards
Randy
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Offline Tim Wescott

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Re: Measuring Epoxy
« Reply #3 on: February 15, 2013, 12:15:44 AM »
This stuff is meant for equal parts.  My mistake was to assume equal densities -- I thought I might warn anyone who's about to make the same mistake as me.
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Offline john e. holliday

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Re: Measuring Epoxy
« Reply #4 on: February 15, 2013, 08:42:10 AM »
I use the little measuring cups and go with equal parts.   I too have noticed the different densities and wonered about the guys that weigh the parts as they mix them.
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Offline RandySmith

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Re: Measuring Epoxy
« Reply #5 on: February 15, 2013, 11:34:00 AM »
Quote from: Tim Wescott on February 15, 2013, 12:15:44 AM
This stuff is meant for equal parts.  My mistake was to assume equal densities -- I thought I might warn anyone who's about to make the same mistake as me.

Yes I knew what you meant, some people may find, though, they have epoxy meant to be mixed by weight, few are , but I have 2 batches here that measure by weight. What ever you have, be sure to measure very accuratly because for some epoxies , that is critical, and they won't dry if not mixed right.

Regards
Randy
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Offline FLOYD CARTER

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Re: Measuring Epoxy
« Reply #6 on: February 15, 2013, 12:17:32 PM »
If I mix up more than a few drops of epoxy, I first put the bottles in the microwave for 10 seconds.  This makes them less viscous and easy to pour.  Of course, when warmed, the densities are quite different.  Therefore, one must use tiny paper or plastic cups to measure out equal volumes.       F.C.
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Offline Bill Little

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Re: Measuring Epoxy
« Reply #7 on: February 15, 2013, 02:39:27 PM »
So far, I have not had any trouble mixing the "hobby" epoxies by volume.  I know that some of the exotic epoxies require mixing by weight but I don't have any of those right now.

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Offline BillLee

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Re: Measuring Epoxy
« Reply #8 on: February 15, 2013, 03:28:12 PM »
Quote from: RandySmith on February 14, 2013, 10:25:32 PM
Most epoxies are to be measured by equal parts, however a few specs call for equal weight, best to check which...

Regards
Randy

Randy,  I think the proper words are "Many epoxies ..." since many are not equal. (Probably most if my investigations into the Shell literature a long time ago is any indication.)  

Now in the world of epoxies for model building ....  :)

Bill
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Offline dave siegler

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Re: Measuring Epoxy
« Reply #9 on: February 17, 2013, 06:23:44 PM »
from the west systems web site


•Dispensing without Mini Pumps (Weight/volume measure) - To measure 105 Resin and 205 or 206 Hardener by weight or volume, combine five parts resin with one part hardener. To measure 105 Resin and 207 or 209 Hardener by volume, combine three parts resin with one part hardener (by weight, 3.5 parts resin-1 part hardener).

When I did a lot of epoxy work, before pumps I had a 5 - 1 teeter totter
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Offline RandySmith

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Re: Measuring Epoxy
« Reply #10 on: February 17, 2013, 09:50:41 PM »
Quote from: BillLee on February 15, 2013, 03:28:12 PM
Randy,  I think the proper words are "Many epoxies ..." since many are not equal. (Probably most if my investigations into the Shell literature a long time ago is any indication.)  

Now in the world of epoxies for model building ....  :)

Bill



Bill  we are talking about epoxies used by the "modelers" posting here, I was not talking about anything in particular that Shell makes ... or any other specific company makes, I assumed "most" everyone understood I am referring to epoxyies that "most" modelers use. The majority of which mixes one to one...either by weight, or volume,  The important thing is that they find out "how" the glues are to be mixed.

Randy
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Offline Howard Rush

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Re: Measuring Epoxy
« Reply #11 on: February 18, 2013, 01:54:04 AM »
The hard part about using the epoxies that Bill wrote about is finding the name of the company that is making them this week.  I use a couple of them.  Good stuff.

Electronic scales are cheap and good now.  It makes measuring epoxy by weight a lot easier than doing it by volume.  I got one with .01 gm accuracy, and I can make tiny batches.
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