# Questions Re: EDTA Use



## KristaY (Mar 9, 2016)

I just got my Lotion Crafter order of Tetrasodium EDTA and I'd like to use it in my CP soap. I've scoured the forum threads and can't find the exact info I'm looking for so I apologize if this info has been covered and I missed it.

The Lotion Crafter site info on EDTA for use in soap says the range is 1.2-4%. I'm not sure how to decide what % to start with. Should I be thinking about the water I use to dissolve the lye (I always use distilled) or the water used to bathe? We don't have terribly hard water in my area but enough for me to notice a gradual increase in soap scum in the shower. So is there a "norm" that soapers use? I read a post by TOMH that said only a gram per 2lbs soap is needed. Also, when do I add the EDTA? Do I dissolve it in the water used for the lye? If so, before or after adding the lye? If not, where and when?

The site also talks about using EDTA in lotions to combat rancidity and act as a preservative. This range is 0.01-0.5% and it says to "add to the water phase". So does this mean I can replace Liquid Germall Plus in lotions with EDTA or can it be in addition to? The site doesn't mention anything about optimal tempertures so is it okay to add at any time? (Liquid Germall Plus is recommended at 122F or below).

TIA to all EDTA users!


----------



## TeresaT (Mar 9, 2016)

This is a screenshot of info I saved regarding citric acid, sodium citrate and EDTA that I refer to constantly.  I'm ashamed to admit that I don't have it memorized.  As often as I refer to it, I really should.  But thanks DeAnna for this incredible info!   (I hope this helps.)


----------



## topofmurrayhill (Mar 9, 2016)

KristaY said:


> I just got my Lotion Crafter order of Tetrasodium EDTA and I'd like to use it in my CP soap. I've scoured the forum threads and can't find the exact info I'm looking for so I apologize if this info has been covered and I missed it.
> 
> The Lotion Crafter site info on EDTA for use in soap says the range is 1.2-4%. I'm not sure how to decide what % to start with. Should I be thinking about the water I use to dissolve the lye (I always use distilled) or the water used to bathe? We don't have terribly hard water in my area but enough for me to notice a gradual increase in soap scum in the shower. So is there a "norm" that soapers use? I read a post by TOMH that said only a gram per 2lbs soap is needed. Also, when do I add the EDTA? Do I dissolve it in the water used for the lye? If so, before or after adding the lye? If not, where and when?
> 
> ...



Keep in mind that EDTA is only a chelator that deactivates metals that might be in your product. Metal ions can provide starting points for oxidation. In general I would call EDTA a stabilizer, but it's not really a preservative. It won't do the slightest thing to protect against biological contamination, so it won't replace anything.

You can dissolve EDTA in your water before adding the caustic, or I guess any water based ingredient for other products. For soap I use 0.1% of the oil weight. I believe that was the usage rate in Dunn's experiments demonstrating its effectiveness, but I'm away on business and don't have the info handy.

My usage rate is based  on using it as a stabilizer in soap to prevent DOS. It doesn't require very much. Some people use it to help increase lather and reduce soap scum in hard water situations, which is what the percentages suggested by Lotioncrafter would be for.


----------



## IrishLass (Mar 9, 2016)

Krista, I use tetrasodium edta in my soaps all the time (we have hard water). I make a masterbatch solution out of the powdered edta with enough warm distilled water to dissolve it/turn it into a 39% solution (39% is the perfect % to keep the edta in solution without precipitating out). I store it in a 12-oz plastic bottle with a flip-top for easy dispensing, and I add as much of the solution as I need to my oils either before or after adding the lye solution (either way works fine).

The rate at which I use the edta is @ .5% of my entire/total batch weight, but that .5% figure is based on the amount of EDTA I need in solid form, which means that I have to do a little bit of math to figure out the amount of 39% solution to use that will ensure that my batch will contain a total of .5% of actual EDTA.

Yep- extra math. I can hear the groans already! LOL No worries, though.  I promise you, the math is very simple (if I can do it, anyone can!). Just follow this simple formula:

1) Total up the _entire_ weight of your batch in grams (i.e. oils, fats, water, fragrance, additives, etc..)
2) The sum of the total weight of your batch multiplied by .5% equals how much of the powdered EDTA needed for your batch.
3) The amount of powdered EDTA needed multiplied by 2.56 equals how much of the 39% solution to weigh out for your batch in grams.

And that's it! 

For my hard water issues, .5% works fine for me, but if your water is not as hard as mine, you can certainly use less of a %. Whatever % you decide to use, sub it in place of the .5% in the above equation in order to get the correct amount of solution to use for your batch/

I hope that made sense. If not, please let me know.....or else maybe someone with a different/easier way of explaining it can chime in.

RE: EDTA in lotions. EDTA is not a preservative and cannot be used tin place of Liquid Germall Plus or any other preservative. Instead of being able to actively kill off bugs like a normal preservative does, EDTA is what is known as a 'preservative booster', whose effects are limited to only being able to starve bacteria of their food by causing a disruption of their digestive system. Basically, it weakens the bacteria, which enables your chosen preservative to have an even greater killing effect. I use it in my lotions at .2% (powdered form) along with phenonip. I heat it with my water phase.


IrishLass


----------



## KristaY (Mar 9, 2016)

Wow. Thanks for the replies! So if I understand correctly, the difference between TOMH and IL's usage rates are based on TOMH working to avoid DOS and IL working to decrease soap scum, right? So if I go with IL's higher % it should accomplish both? Here's the math I've done based on a common recipe of mine:

Total batch weight of oils + water + lye + additives = 1450gms. Of this, 1020gms are oils only.

Using TOMH's method I multiplied 1020gms x 0.1% and got 1.02gms EDTA.

Using IL's method I multiplied 1450gms x 0.5% which equals 7.25gms EDTA.

I decided to go with simple math to make the 39% solution of EDTA which should be 39gms EDTA + 61gms H2O = 100gms total solution.

From here I multiplied 2.56 x 1 = 2.56gms of 39% solution for TOMH's method. Then 7.25 x 2.56 = 18.56gms of 39% solution per IL's method.

Since my scale weighs in whole grams only I'll round numbers up or down accordingly. So now I can choose from 1-7gms powdered EDTA or 3-19gms of the 39% solution. Whew, I hope I'm doing this right, lol.

From here I can add it in either powder or solution to the lye water (before lye) or into the oils before lye solution.

Does this look right to everyone that isn't allergic math? :shock:

Thank you both for clearing up the confusion I had about EDTA use in lotion. I'll give it a try next time by adding .2% to the water phase.


----------



## topofmurrayhill (Mar 10, 2016)

KristaY said:


> Wow. Thanks for the replies! So if I understand correctly, the difference between TOMH and IL's usage rates are based on TOMH working to avoid DOS and IL working to decrease soap scum, right? So if I go with IL's higher % it should accomplish both? Here's the math I've done based on a common recipe of mine:
> 
> Total batch weight of oils + water + lye + additives = 1450gms. Of this, 1020gms are oils only.
> 
> ...



Sounds like you've got a handle on it. The usage rate isn't cast in stone, but IL's rate is somewhat overkill as a stabilizer so that would be to fight hard water. For the lower usage rate I'd add it to the lye water as it will dissolve in a jiffy and chelate any metal ions in your batch water off the bat.

I take back the part about it not having any antimicrobial effect. It's interesting to learn that it does to some extent. I don't think the manufacturers talk about that so nobody leaves out a preservative.


----------



## TeresaT (Apr 1, 2016)

IrishLass said:


> Krista, I use tetrasodium edta in my soaps all the time (we have hard water). I make a masterbatch solution out of the powdered edta with enough warm distilled water to dissolve it/turn it into a 39% solution (39% is the perfect % to keep the edta in solution without precipitating out). I store it in a 12-oz plastic bottle with a flip-top for easy dispensing, and I add as much of the solution as I need to my oils either before or after adding the lye solution (either way works fine).
> 
> The rate at which I use the edta is @ .5% of my entire/total batch weight, but that .5% figure is based on the amount of EDTA I need in solid form, which means that I have to do a little bit of math to figure out the amount of 39% solution to use that will ensure that my batch will contain a total of .5% of actual EDTA.
> 
> ...



OK, IL, I've got a few questions for you.  Krista redirected me here from the Honey Soap thread to learn about EDTA.  

1.  Where did you get the 2.56 number from to multiply in step #3?  
2.  The "average" rate is .5%.  What if I use more, say 1%?  Will that cause irritation?  Skin to fall off?  Mutant life forms in the next generation?  (I just read about the evils of phthalates.)

Thanks!


----------



## IrishLass (Apr 1, 2016)

TeresaT said:


> OK, IL, I've got a few questions for you. Krista redirected me here from the Honey Soap thread to learn about EDTA.
> 
> 1. Where did you get the 2.56 number from to multiply in step #3?


 
You just _had_ to ask me that, didn't you?! LOL Brace yourself for some math! Muahahaha! (just remember that you asked for it  )

This is where the 2.56 comes from:

Once you have figured out how much powdered EDTA in grams and how much water in grams it will take to make up the amount of 39% solution that you wish to master-batch, add both those gram figures together. Next, take the resulting sum from that equation, and divide it by the gram amount of powdered EDTA it will take to make your solution. The resulting sum will be 2.56g....always...no matter what the size of EDTA master-batch solution you are making.

For example, I normally make enough 39% EDTA solution to fit inside a 12-oz plastic squeeze bottle. This requires 181.4g of powdered EDTA and 283.4g of distilled water:

181.4g powdered EDTA + 283.4g Distilled Water = 464.8g 39% solution

464.8g 39% solution divided by 181.4g powdered EDTA = 2.56g


But let's say I wanted to make a much bigger master-batch amount of 39% EDTA solution.... maybe something like 897.5g worth of 39% solution. That will take 350g powdered EDTA and 547.4g distilled water.

350g powdered EDTA + 547g distilled water = 897.5g 39% solution

897.5g 39% solution divided by 350g powdered EDTA = you guessed it.....2.56g

In essence... however much powdered EDTA x 2.56 = the liquid weight the 39% solution.

Ta da! Hopefully all that made sense. 





TeresaT said:


> The "average" rate is .5%. What if I use more, say 1%? Will that cause irritation? Skin to fall off? Mutant life forms in the next generation? (I just read about the evils of phthalates.)
> 
> Thanks!


 
According to the tetrasodium EDTA fact sheet on the LotionCrafter site: http://www.lotioncrafter.com/reference/tech_data_edta.pdf ,for use in soap, the usage rate to "counteract defoaming action of hardness ions" is 1.2 to 4%. I decided to use .5% as per my total batch weight because that was the amount recommend by a microbiologist and a handful of others on another soaping forum. That was the amount they personally used and had success with, so that's where I decided to start (best to start off low rather than high to see how little I can get away with, I always say). It worked well enough for me at that level- my soap's lathering ability increased and my soap scum decreased- so I never increased it beyond that. I still get soap scum, mind you, but it's a lot less than it used to be. I often think about trying a batch with more to see how it fares, but I just haven't done so yet.


IrishLass


----------



## DeeAnna (Apr 1, 2016)

Multiplying by 2.56 is the same as dividing by 0.39. The 0.39 comes from the 39% EDTA solution that IL is using.

If you use more than the usual 0.5% in your soap with the goal of controlling soap scum, the EDTA may cause the lye solution or the soap batter to turn into a thick white pudding-like stuff. (Highly technical term there!) Also, you may find that more EDTA doesn't necessarily translate to better control of soap scum, especially in bath soap, but that will depend on the hardness of your water and whether you shower or take baths.

I tried EDTA at 3% in a laundry soap ... once ... and I decided I won't do that again. I didn't see any great benefit to using that much EDTA even in laundry soap. Also the pudding issue was a downside. I realized there is no point in using more if I get perfectly good results with less. I've decided to use 0.5% in bath soap and 1% in laundry soap.


----------



## ngian (Apr 1, 2016)

Nice info on this thread as these days I found tetrasodium edta at ~5€ / kg (~90% purity) and I'm planning to test it at 0.5% against the 4% sodium citrate I already use...


----------



## TeresaT (Apr 1, 2016)

Thanks, IL.  That makes perfect sense to me.  And thank you, too, DeeAnna.  I love how y'all always break things down so I can understand them.  I, in turn, share your knowledge with others.  Today my insurance company called me back about getting business insurance & we got talking.  That lady knows more science today than she did yesterday!!


----------



## RDak (Apr 2, 2016)

FWIW, if you want to use the straight powder you can put into the water before the lye, or do what I do and just add it to the oil before mixing in the lye water and stick blend the whole concoction.

It works fine either way.

ETA: For example if you want 0.5 percent just multiply the total grams of your recipe.......let's say 3,000 grams and multiply by 0.005 and you get the grams needed, or 15 grams of EDTA powder.


----------



## Sonya-m (Apr 2, 2016)

Just ordered some more EDTA, always added to my water before lye but I'm going to master batch this order. Thanks to IrishLass, the calcs seem easy enough


----------



## ngian (Apr 7, 2016)

Another soaper gave me some tetrasodium EDTA powder in order to see how this can help with soap scum.






So some new to do experiments are on the list:

- 4% SodiumCitrate vs 0.5% EDTA
- 0,5% vs >1% EDTA

and maybe

- 3% SodiumCitrate and 0,5% EDTA both in soap

Now only time is what I need.

ps. Yes, vinegar also lengthened my to do list...


----------



## Saponista (Apr 7, 2016)

I'm really interested to see if it is better than the citrate. I looked at it and it is much more expensive to buy than the citrate, but perhaps not so bad if you use it at a lower concentration.


----------



## ngian (Apr 7, 2016)

Saponista said:


> I'm really interested to see if it is better than the citrate. I looked at it and it is much more expensive to buy than the citrate, but perhaps not so bad if you use it at a lower concentration.




In my town I can find Sodium Citrate @ 3,5E / kgr and EDTA @ 4,5E / kgr and I think it will be difficult to understand if one is better than the other.

I have very hard water and I use in all my latest soaps sodium citrate. I have seen that a soap with SC can make a little bigger bubbles than a soap without it when everything else is equal, and the tub is not getting so much dirt because of soap scum at a relatively same time range.

If 0.5% of EDTA can have the same results with 4%SC, then I think that one can say it's better because of its strength.

Here are the results than the *Lather Lovers Swap 2012* had with these two ingredients:


----------



## DeeAnna (Apr 7, 2016)

IrishLass said:


> ...I decided to use .5% as per my total batch weight because that was the amount recommend by a microbiologist and a handful of others on another soaping forum.... It worked well enough for me at that level- my soap's lathering ability increased and my soap scum decreased- so I never increased it beyond that. I still get soap scum, mind you, but it's a lot less than it used to be. I often think about trying a batch with more to see how it fares, but I just haven't done so yet.



Like IL, I don't expect to eliminate all soap scum by using a chelator in my soap. That is a job beyond what a chelator can do. I instead think of a chelator in bar or liquid soap as a "point of use" water softener -- I want it to treat the water right where my skin is so the hard water minerals rinse off rather than stick to my skin.

If I wanted to add enough a chelator to treat a larger volume of water such as an entire bathtub filled with water, a sink full of dishes, or a washing machine packed with of laundry, there would be more chelator than soap in my "soap." That's the reason why a water softener is also important. It can be a resin bed that household water passes through (the water softener gadget that is fed with salt), a powdered zeolite product that is added to the laundry wash water (Calgon water softener additive), or a large municipal water-softening plant that treats all of the water for a town or city.


----------



## KristaY (Apr 7, 2016)

Saponista said:


> I'm really interested to see if it is better than the citrate. I looked at it and it is much more expensive to buy than the citrate, but perhaps not so bad if you use it at a lower concentration.



This is buying EDTA in the states, mind you, so I don't know if it will completely apply but by adding 5 grams to a 3lb batch the cost is 18 cents. This batch makes 9 bars so it increased the cost of each bar by only 2 cents.


----------



## IrishLass (Apr 7, 2016)

DeeAnna said:


> Like IL, I don't expect to eliminate all soap scum by using a chelator in my soap. That is a job beyond what a chelator can do. I instead think of a chelator in bar or liquid soap as a "point of use" water softener -- I want it to treat the water right where my skin is so the hard water minerals rinse off rather than stick to my skin.


 
Very true^^^. When talking about EDTA in my soap, I pretty much have only ever talked about the positive effects is has had on the performance of my soap's lathering abilities, as well as the reduction of soap scum in my shower and sinks, but I don't think I've ever mentioned how wonderfully clean my soap's lather rinses off my skin since I've been including it in my formulas. Before it's inclusion, my skin used to get that draggy/squidgy feeling when rinsing the lather off in our hard water, although it wouldn't do that at my sis's house(she has a water softener). Since adding it to my soap, the lather rinses off smoothly, just as if we had a water softener.


IrishLass


----------



## ngian (Apr 7, 2016)

IrishLass said:


> ...but I don't think I've ever mentioned how wonderfully clean my soap's lather rinses off my skin since I've been including it in my formulas. Before it's inclusion, my skin used to get that draggy/squidgy feeling when rinsing the lather off in our hard water, although it wouldn't do that at my sis's house(she has a water softener). Since adding it to my soap, the lather rinses off smoothly, just as if we had a water softener.



Thank you for the specific feedback IrishLass, that will help me understand any difference by its usage.


----------



## Dahila (Apr 21, 2016)

Ladies you are fantastic , I ordered my EDTA already and came here to find how it works.  Thank you for simple solution


----------



## Julta (Oct 3, 2019)

Thank you IrishLass for the above breakdown. I was also wondering about the 2.56 and you couldn't have explained it better. This info is gold

I would like to do a laundry bar soap for use in hard water and I hope to share the results soon.

Thanks


----------



## DeeAnna (Oct 3, 2019)

See also this update on how to make an EDTA solution: https://www.soapmakingforum.com/threads/yes-virginia-you-can-make-a-50-edta-solution.62761/


----------



## linne1gi (Oct 4, 2019)

I also liked this discussion, and just realized it was from 2016!  At first I thought about making up a 39% EDTA solution as described (right now I just use the powder) - but then realized that using the solution would increase my water amount.  I do a water discount and really don't want to increase my water - so after all is said and done, I'm going to continue with just using the powder at .5%.


----------



## DeeAnna (Oct 4, 2019)

It doesn't have to increase the total water if you don't want it to. If you make a 50% EDTA solution, as I describe in the link in my previous post, then half the weight of this solution is water. Subtract half of the solution weight from the total water weight and you're back on track. I do this for all my recipes. 

If you use an NaOH masterbatch, you have to adjust for the water in the NaOH solution. The way you do this correction for EDTA solution is exactly the same.

It wouldn't surprise me if the SoapMaking Friend calc will do the math for you. If it doesn't, I suspect the developers would add that if you asked. But it's not hard to do by hand, especially if you use a 50% EDTA solution.


----------



## linne1gi (Oct 4, 2019)

Thank you.  This has been explained very nicely.


----------

