Epoxy metered pumps

Scott H

Scott
User
I got some 5:1 epoxy a while ago (Totalboat to start, maybe will change to West Systems when this runs out) and I got the metered pumps because it sounded like such a great idea to not have to measure.

Unfortunately it turns out that I use so little epoxy so infrequently that the pumps lose their prime. To prime them again is like a few pumps before the pumps are continuous and smooth.

What in the heck are you supposed to do with the resin and hardener that comes out of the incomplete pumps that happen when you prime them? It is more than I use in a batch of actual epoxy and the mix ratio is unknown. It seems like an enormous waste to just mix it and not use it. I contacted the vendor and they said I could refill the bottles with it. I tried refilling and let me tell you that is a godawful mess. Uncured resin and hardener has to be disposed of specially. Plus I worry about cross contamination like accidentally getting minute amounts of hardener into the resin container during this process.

Should I just give up and always mix by volume or weight? Are these metered pumps really for people that are actually using a lot of epoxy almost daily? Any other tips?
 

tri4sale

Daniel
Corporate Member
I got some 5:1 epoxy a while ago (Totalboat to start, maybe will change to West Systems when this runs out) and I got the metered pumps because it sounded like such a great idea to not have to measure.

Unfortunately it turns out that I use so little epoxy so infrequently that the pumps lose their prime. To prime them again is like a few pumps before the pumps are continuous and smooth.

What in the heck are you supposed to do with the resin and hardener that comes out of the incomplete pumps that happen when you prime them? It is more than I use in a batch of actual epoxy and the mix ratio is unknown. It seems like an enormous waste to just mix it and not use it. I contacted the vendor and they said I could refill the bottles with it. I tried refilling and let me tell you that is a godawful mess. Uncured resin and hardener has to be disposed of specially. Plus I worry about cross contamination like accidentally getting minute amounts of hardener into the resin container during this process.

Should I just give up and always mix by volume or weight? Are these metered pumps really for people that are actually using a lot of epoxy almost daily? Any other tips?

I just do it by weight, have digital scale in garage just for epoxy and a bunch of throw away plastic cups.
 

tvrgeek

Scott
User
you may find more precise answers on the home built aircraft forums. I just used the West pumps. Never had an issue.
 

smallboat

smallboat
Corporate Member
I always thought the pumps metered by volume and that’s what the ratio refers to. Is the density of resin and hardener similar enough that mass works just as well?

Just curious, never thought about this before, or researched it. It could be handy to know.
 

smallboat

smallboat
Corporate Member
Well, just had to go find out. This from the WEST System data sheet
Handling Characteristics
Mix ratio by volume (300 Mini Pump ratio) ................5 parts resin : 1 part hardener
by weight ................................................................................................5.19 : 1
Acceptable ratio range by weight ....................................................4.83 : 1 to 6.20 :1

Now we know!
 

Hmerkle

Hank
Corporate Member
Well, just had to go find out. This from the WEST System data sheet


Now we know!
O.K. so for the "Hard of thinking" that is Mix ratio by volume (300 Mini Pump ratio) ................5 parts resin : 1 part hardener
Or by weight - 5.19 : 1
Meaning 25 grams of hardner and 1.19 *25 for the resin (25*1.19= 29.75) ~30grams....

Right?
(not 5.19 that would be 129.75 grams....)
 

smallboat

smallboat
Corporate Member
No it would be 129.75 g of resin for 25 g of hardener.
Slightly more than 5 times as much resin as hardener of you go by weight.
Exactly 5 times as much resin as hardener if you go by volume.

Lots of resin, little hardener.

this is true for these specific products, not universally.

Different epoxies have different ratios.

Even systems where you can pair the same resin with different hardeners may have different ratios for the different hardeners.

Follow the manufacturer‘s directions.
 

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