The science of ash

[SudsyKat]

So, I got my first bona fide ash layer on a batch of soap. Boo hoo. Not a huge deal - I'm just going to cut it off. I have a comment and a question. The comment is that the ash was barely visible when I first cut the soap (almost 5 weeks ago), and it took this long to really show - it's bright white. I was surprised that it took this long (maybe the rest of the soap got darker - who knows).

Anyhow, my question is - what is the science behind the ash problem? What causes it, specifically? I know I can do the alcohol spraying thing (and I will in the future), but why does that help? Is ash caused by exposure to air, a problem with the formula, a temperature issue? Just wondering because I'd like to do more than just spray alcohol. I'd like to avoid the cause to begin with.

Thanks!

 

[soapbuddy]

I stopped getting ash when I started using beeswax. I don't know the sceince behind it, but know that it works.

 

[soapopera]

I too recently got ash. I'm actually slowly experimenting and having a hunch it might got to do with Palm oil. The batches I'd made without Palm have no ash even I peek at it gadzillion time. I'd made 2 batches with Palm in it and both have a light dusting (like icing sugar) on the top.

 

[agriffin]

Most lye contains some impurities including sodium chloride, sodium carbonate and calcium hydroxide (there are some others as well). These impurities are incapable of combining with fat.

After you pour your soap and during saponification these foreign salts/materials rise to the surface and appear like crystals or a white film.

I think that several things can affect the "movement" of these impurities including:

beeswax - why? not sure...it might somehow bind them in the mixture
temps of soap mixture
oils used
covering your soap with plastic wrap; maybe only when they come in contact with air they crystalize (not sure...just talking out loud)

Alcohol works by dissolving these particles.

 

[cwarren]

Thanks for the question and answer ! interesting !!

 

[soapopera]

Yeah! This is interesting. Thanks for explanation.

 

[missybee]

Would spraying the tops with alcohol and wiping them off with a terry cloth get rid of it,or do you need to actually discard that section of the soap?

 

[honor435]

embrace the ash! I think it looks cool, most times.

 

[SudsyKat]

agriffin - that was so helpful. Thank you! I'm thinking that I may just need to buy technical grade lye online (which I was thinking about doing anyway) instead of the stuff from the hardware store. Do you know what the difference is between the technical grade and the food grade lye (because they both claim to be much purer than drain opener lye and better for soap)?

Also, to be honest, I don't know if I've got "ash" or not. I thought for sure that's what it was because it's a solid white layer of soap on the top of the soap bar. But it is in no way crystalized or a "dusting". It's a very thin layer of white soap. It does not come off. Anyhow, frankly, the stuff online, if you order enough of it, is just as economical as buying it at the hardware store.

I'd love your input on this. Thanks again![/list]

 

[American Valkyrie]

I use high food-grade lye from here:
http://www.amazon.com/Grade-Sodium-Hydr ... 663&sr=8-1
Even with the high shipping rates, it's 3 cents per ounce cheaper than the local hardware store, and that's not including my gas/time costs.

I get ash in 1 in every 4 batches, even with how pure this is. It's just a very thin layer that I can rub off with my finger. I haven't done the alcohol yet... since I'm starting on pretty tops, it looks like that's what I need to buy next.

 

[ToniD]

Is there an alcohol that works better than others? The stuff I use does not seem to have any effect.

 

[SudsyKat]

ToniD - there's a current thread about spraying alcohol. Could be helpful - http://www.soapmakingforum.com/forum/vi ... 1&start=30

American Valkyrie - That's the same company I was going to order from. FYI, it's slightly cheaper overall (with shipping) to buy directly from their website (http://www.essentialdepot.com) than to buy off Amazon (even with the "buy 5, get $15 dollars off" deal on Amazon).

 

[American Valkyrie]

American Valkyrie - That's the same company I was going to order from. FYI, it's slightly cheaper overall (with shipping) to buy directly from their website (http://www.essentialdepot.com) than to buy off Amazon (even with the "buy 5, get $15 dollars off" deal on Amazon).

Ooh that's even better! Thanks!

 

[Lindy]

I stopped getting ash when I started using beeswax. I don't know the sceince behind it, but know that it works.

I haven't heard that before - now I gotta try it... :shock:

 

[SudsyKat]

How much beeswax do you use? I've never used it in a recipe. Is there a downside? Is it really beeswax (as in, from bees)?

 

[soapbuddy]

How much beeswax do you use? I've never used it in a recipe. Is there a downside? Is it really beeswax (as in, from bees)?

I use 1 to 1.5%. Yes, it's really beeswax from the bees.
I haven't seen or felt a downside.

 

[Bubbles Galore]

I too recently got ash. I'm actually slowly experimenting and having a hunch it might got to do with Palm oil. The batches I'd made without Palm have no ash even I peek at it gadzillion time. I'd made 2 batches with Palm in it and both have a light dusting (like icing sugar) on the top.

No, it's not the palm oil. I've got 3 un-gelled batches of palm free soap in the soap room, all with varying degrees of ash on top. 6% lye discount and 0% water discount and all fragranced with FO. Log moulds, then cut up after 24 hours and no ash on body of soap, just on top.

Same recipe with 10% lye discount and 20% water discount made with goat milk, in single silicone moulds, unfragranced, gelled - no ash. No beeswax in any. :wink:

 

[Jerry S]

The dreaded ash problem

U made and interesting point Bubbles, about the higher superfating and using 20% water discount made with goats milk. I may have to try this if I don’t want the ashy look on some of my bars, it sort of looks earthy though. I got a kick out of honor435 saying “embrace the ash! I think it looks cool,”
When you discount the water 20%, do you make that up with the goats milk, or do u substitute the water altogether with the goats milk? Can I buy goats milk in the market? (I have not goats) ..never used it..but would regular milk work?
Jerry S

 

[albo]

I've got a batch that I made some guest size soaps in individual moulds, and some larger bars in individual moulds. The guest soaps behaved, and were out of the mould within 24hours. The larger bars I couldn't get out (poor choice of mould) and they sat there for about a week before I cracked it and cut them out. The small soaps have ash, the larger ones do not.

So if we work on the theory of stuff within the lye crystalising, obviously there's a timeframe for that to take place to cause ash, and if we wait past that time to expose the soap to air maybe we can avoid the problem?

 

[SudsyKat]

Funny thing - I have a sense (not based on anything concrete) that it has something to do with exposure to air. Again, I'm not an expert and can't pin it down for sure, but l like Albo's reasoning. I did buy some 100 proof alcohol and will try spritzing as well, but I'm also going to not peek.

Of course, this doesn't mean that the other factors mentioned in this thread are not valid. I'll have to experiment. Thanks for all the input!