Epoxy primer (Interprotect) mixin ratio by weight?

[Lomax]

Epoxy primer (Interprotect) mixing ratio by weight?

Having perused International's datasheet I was surprised to see they do not give a "by weight" mixing ratio, only "by volume". I'd like to use my digital scales, which do percentage, but haven't been able to find the weight ratio anywhere. I suppose I could just weigh equal volumes of each component and work backwards from there, but it would save me the hassle if anyone knows?

Side note: other paint manufacturers, e.g. Epifanes, list this in their datasheet!

 

[VicS]

Having perused International's datasheet I was surprised to see they do not give a "by weight" mixing ratio, only "by volume". I'd like to use my digital scales, which do percentage, but haven't been able to find the weight ratio anywhere. I suppose I could just weigh equal volumes of each component and work backwards from there, but it would save me the hassle if anyone knows?

Side note: other paint manufacturers, e.g. Epifanes, list this in their datasheet!

You could work out the weight ratio from the relative densities which you will find in the Chemical and Physical properties section of the safety data sheets .

Or you could ask their "friendly help desk":

We're here to help
Our friendly help desk is open weekdays 8:00 - 16:30
Call 01489 775062
Send an e-mail to iyp.uk@akzonobel.com​

 

[coopec]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

Lomax

I would do just as you've said. Measure the whole of the Part A and the whole of the Part B. Then work out the ratio of Part A to Part B and mix accordingly.

I bought a whole lot of different sized measuring (plastic) "flasks" on eBay (very, very cheap). If the ratio is 4:1 that is what I mix using the appropriate sized flask,

Clive

 

[Lomax]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

Thanks guys, here's what I've just done:





I measured a quantity of water (measure said 250ml, scales 220g) and carefully scribed a line on the plastic cup with a Sharpie, then transferred the water to a second cup and scribed a line on that too. I carefully dried both cups, before filling each with part A and part B respectively, and weighed these (don't worry about the "cal now" on the display; my scales demand recalibration every time they've been unplugged but they were calibrated yesterday in the same location). So the numbers are, for the equivalent of 220 grammes of water:

Part A: 343g
Part B: 193g

Which gives (343 x 3) / 193 = 5.33:1 ratio by weight.

 

[coopec]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

Where do you get the 343.3 from? Why have you got it in brackets in your equation?

343.3/193 = 1.77875647668. How on earth do you get 5.33:1 ratio by weight? Where did you get that from?

I don't follow you maths at all. Have you missed a few steps?

Why don't you go by volume as the manufacturer directs?

Clive

 

[GHA]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

:encouragement:

I've used a syringe before weighing 100mL of each part, but a plastic cup makes so much more sense, less cleaning to do. Kitchen scales are great for mixing small amounts of epoxy accurately, every boat should have some - heard some people even use them for cooking as well!!

 

[VicS]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

Where do you get the 343.3 from? Why have you got it in brackets in your equation?

343.3/193 = 1.77875647668. How on earth do you get 5.33:1 ratio by weight? Where did you get that from?

I don't follow you maths at all. Have you missed a few steps?

Why don't you go by volume as the manufacturer directs?

Clive

The dot in 343.3 is mathematical short hand for multiply

343 x 3 /193 = 5.33 !

But why he had to faff about with cups of water etc when he could have calculated the ratio from the density figures is beyond my understanding.

 

[coopec]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

The dot in 343.3 is mathematical short hand for multiply

343 x 3 /193 = 5.33 !

But why he had do faff about with cups of water etc when he could have calculated the ratio from the density figures is beyond my understanding

Thanks Vic.

I've studied a lot of maths and taught Business Maths and never seen that mathematical s/h.

Talk about making an easy job hard!

( I just tried to google that equation to solve it and it doesn't recognize the format at all). It came up with "Catalytic Asymmetric Conjugate Reactions"!

Clive

 

[Lomax]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

Where do you get the 343.3 from? Why have you got it in brackets in your equation?

My apologies, it's intended to be a multiplication sign (asterisk). Updated to an "x". The maths are sound.

Why don't you go by volume as the manufacturer directs?

You've never used one of those scales, have you? It allows me to mix any quantity, accurately and quickly, thanks to having a built in percentage function. Given the high cost of Interprotect (2.5L cost me almost £100!), and the short pot life (3h according to datasheet, a bit less in my experience), there are significant savings in being able to mix just enough for the job, which would be time consuming and messy if done by volume.

 

[Lomax]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

But why he had to faff about with cups of water etc when he could have calculated the ratio from the density figures is beyond my understanding.

What? Where did you see these? It's not listed in the datasheet, from what I can see?

 

[Lomax]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

I've studied a lot of maths and taught Business Maths and never seen that mathematical s/h.

How odd - it's on pretty much every single keyboard I've ever seen that has a numerical keypad. Maybe you don't use these in business maths classes?

 

[GHA]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

But why he had to faff about with cups of water etc when he could have calculated the ratio from the density figures is beyond my understanding.

Cause epoxy is so expensive it's better to trust nothing and double check , even if you can get hold of the density figures. Only takes a moment.

 

[Tranona]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

How odd - it's on pretty much every single keyboard I've ever seen that has a numerical keypad. Maybe you don't use these in business maths classes?

View attachment 71542

The convention is to use the * for multiply. There is one on my numeric keypad or on shift8

 

[coopec]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

GHA

Yes it is expensive. I buy it in a 3kg kit (2:1) and measure it out using my little plastic beakers as accurately as I can. I'm always interested to see if I come to the end of my Part A as I come to the end of my Part B. It is always very close but almost always there is a little Part B left over and I wonder if they deliberately pack it that way.

Clive

 

[coopec]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

The convention is to use the * for multiply. There is one on my numeric keypad or on shift8

Yes I'd go along with that

Clive

 

[coopec]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

How odd - it's on pretty much every single keyboard I've ever seen that has a numerical keypad. Maybe you don't use these in business maths classes?

View attachment 71542

Well that is an asterisk on my keypad! (That is of course used as a multiply symbol.)

 

[Lomax]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

The convention is to use the * for multiply. There is one on my numeric keypad or on shift8

Jesus. WTF is wrong with you people. Are we going to argue about character encodings and web browser font rendering now!? I don't know why my asterisk turned up as something which more resembled a "middle dot", but I have already addressed this:

My apologies, it's intended to be a multiplication sign (asterisk). Updated to an "x".

Please give it a rest.

 

[GHA]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

GHA

Yes it is expensive. I buy it in a 3kg kit (2:1) and measure it out using my little plastic beakers as accurately as I can. I'm always interested to see if I come to the end of my Part A as I come to the end of my Part B. It is always very close but almost always there is a little Part B left over and I wonder if they deliberately pack it that way.

Clive

I use epoxy paint more, sometimes in very small quantities, scales are great for that - down to the gram, very accurate and no clean up. Then after the first cot you get an idea of how much the area needs for the next multiple coats.
Give it a go :encouragement:

Love my scales dearly, they get a lot of use

 

[GHA]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

Jesus. WTF is wrong with you people. Are we going to argue about character encodings and web browser font rendering now!? I don't know why my asterisk turned up as something which more resembled a "middle dot", but I have already addressed this:



Please give it a rest.

people aren't wearing enough hats

 

[Lomax]

Re: Epoxy primer (Interprotect) mixing ratio by weight?

:encouragement:

I've used a syringe before weighing 100mL of each part, but a plastic cup makes so much more sense, less cleaning to do. Kitchen scales are great for mixing small amounts of epoxy accurately, every boat should have some - heard some people even use them for cooking as well!!

Thanks. Nice to see at least someone gets it. Those scales are one of my most frequently used instruments; the 0.1g resolution makes them useful for all kinds of paint/glue/general chemistry applications, and it has lots of handy built in functions, such as the aforementioned percentage function and parts counting. It also has an RS-232 port for data logging when you want to plot a change in weight over time. And yes, I sometimes use it for cooking as well!