Dennis, your maths seems correct to me!

However, I tend to keep things "simple stupid" and use quantities based on 100parts resin or simple divisions of, to make the hardener calculation much easier in your head when in the workshop. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Unless I have been doing it wrong...here is how I get my totals. Everything has cured in the proper time so I think I am doing it correct.    First figure out how much total resin you need then divide that number by the mix ratio... Example....if you need 550 grams total and you have a 100:30 mix ratio divided 550/1.3=423.07 grams of resin.  So then fill a cup to 423g of resin then fill with hardener to 550g. 

If you happen to go over the amount of resin you were sopose to like say you end up with 432g of resin just multiply that by the mix ratio for the new total. example....432x1.3=561.6 total.

Also if you need to figure how big of a cup you will need to mix in just multiply the total resin by .035274 This will give you how many ounces that amout of resin is.  example.....550grams = 19.4oz  

hope this helps,

 Dennis

thanks for the information Fred, 

Hi Matt
The pumps aren't that accurate and I wouldn't trust them to this expensive type work.
When I had the pumps I simply used them to dispense the resin into a mixing cup on the scales watching the scales and ignoring the number of pumps. It sure was neat and easy to mix really small batches accurately. Because they eventually screw up and they cost too much to keep replacing them I decided not to use them.
A little trick I learned while dribbeling the resin all over the place trying to pore out of a gallon can was this. Pore some resin into a clean cup and then pore this into your mixing cup very accurately. No mess, do the same with the hardener from another clean cup. Pore the resin you don't use back into its container. ( Make sure you don't get mixed up when you pore the unused materials back into its original container or your going to have problems.) To bad they didn't make a squeeze top you could screw on like a mustard container???
Hope this helps.
Fred     

Good news, my first mould is done and dusted! Many lessons learnt and i had a blast. 

thanks for your time and good information Matt, I didn't know there were so many "problems" with them!

Hi Philimon,

I'll take a look into whether we can make the labeling any more clear. I'm not aware of anyone else misinterpreting the labeling but I guess that doesn't mean it's never happened. I think we do also show some example mix ratios on that same bottle which I would have thought would confirm the mix ratio on the front?

Matthieu,

We have considered this, the primary reason against is accuracy but there are in fact several other reasons why these pump/volume based systems are not favoured. On the accuracy front it's impossible to properly have 'half' a pump or a 'quarter' of a pump so you end up rounding everything up, you do also need to prime the pumps which means wasting some usually and the pumps themselves leave the epoxy and hardener exposed to air (so they deteriorate faster and absorb moisture). Also, because you can't get exactly the right ratios needed in the pumps themselves (unless they're made specifically which is thousands in tooling costs) the resins need to be modified to be at the correct ratio for the pumps which might mean some compromise on the performance or behavior of the resin.

To get the accuracy you need on the scales it's worth having a couple of sets. The very accurate 'gram scales' which measure to 1/10th of a gram (0.1g) are great for tiny quantities and then for larger quantities a second set which measures to a 1g accuracy is fine.

All the best, Matt


Matt Statham
Easy Composites / Carbon Mods - Technical Sales

@Matthieu you can easily find cheap scales that are very precise (talking about 1/10th gr precision, sometimes even more), the thing is they can't weight more than 500gr. So perhaps using the scale you have now for larger quantities, and using the small scale for small quantities.
I used to do that. In any case the day I've been able to afford a pro scale things got so much easier.

Seb

The only problem with dispensing pumps they can some times give the wrong amount,they can be a pain if not using regular you have to prime them,using scales is much more precise.But I do understand the convenience of pumps.  

If the EC-guys read this,