Thursday, February 09, 2006

Why do my colours bleed?

I'm asked this question frequently, so I thought I'd address it here. This is more of a problem with melt & pour soap than with cold process. It's also only a problem with the dyes, not the pigments. So, that having been said, why?

They both colour the soap differently. The dyes are water soluable, they dissolve in water. The pigments (and micas) are water dispersible, so they disperse in water. Picture this. You add a spoonful of sugar to your tea and stir it, the sugar dissolves. Then you add a teaspoon of sand to your tea and stir it, the water disperses, but when you stop stirring, the sand settles, it won't dissolve in water. That is the difference between the dyes and the pigments.

The dyes, when added to melt & pour soap, dissolve in the water in the soap, but when it's touching a layer with a different colour, they mingle. Even more so if the soap is hot and starts to melt the first layer.

The pigments are teensy weensy rocks, and as your soap hardens, the "rocks" are trapped throughout the soap, but never dissolve. As you use the soap, the "rocks" rinse away (and sometimes leave colour on the washcloth temporarily).

Personally, I like working with the pigments more than the dyes. The colours stay true. I do find though that in melt & pour soap, there will always be some sediment from the pigments in the bottom of the soap pot, that has settled. No matter how long I stir or how cool the soap gets before I pour it, there's still a bit of settling, so the last wee bit with the sediment gets tossed, but it's only about a half a teaspoon.

The advantage to the dyes is the more vibrant colours, because they're synthetic. The pigments are muted colours, more like nature's colours. The other advantage is the clarity in transparent soap. The dyes don't effect that at all, while pigments, because they're those teensy weensy "rocks" will have some affect in the clarity.


While I'm on the topic of colours, another frequent questin is about the FD&C or FD in the names of the dyes. FD&C means it is approved for use in food, drugs & cosmetics, the D&C means it's approved for use in drugs and cosmetics only.

If you have any other questions about the colourants that you'd like to ask, leave them in the comments and I'll do my best to answer them.

1 Comments:

At Sunday, February 19, 2006 1:31:00 AM, Blogger Angela said...

Hi Wendy,

Just wanted to say congrats on getting a blog! Arn't they fun? lol. You were the first place I bought essential oils from way back in 2001 I think or maybe earlier..

Anyway,
keep bloggin :)
Angela

 

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