I've not used glitter in soap, as in made the soap and added glitter so I can't say. But I do know the glitter needs to be finer than typical craft glitter. But I have used soap or was a bath bomb or bubble bar from LUSH, well it was something and I remember it being very scratchy because the glitter was too big. They should have known better. We were on holiday and went to the MOA (Mall of America) and I was curious about LUSH products as there is a store there. Even though I like mine better. But that didn't stop me from walking out with a bag full... I couldn't resist their over-priced, terrible quality products that are overscented.
The size makes a difference and it doesn't take much to feel scratchy to the skin.
If your going to add it to lip balm I would say yes it also needs to be lip safe or food safe. There are many colorants that have shimmer that are lip safe.
TKB offer colorants and glitter that are safe for the lips. http://www.tkbtrading.com/category.php?category_id=17
But an option that might be closer to you or you might have a chance at buying it when you travel to a larger town. I don't know where you live but I live in a very rural area. But I have bought some Wilton products that had shimmer and was glittery. I don't recall what it was called exactly, but you want it to be powder fine. I think what your looking for may
be Wilter Shimmer Dust
. You may want to add a tiny bit to some oil and apply it to your lips before adding some to the whole batch.
I bought several colors a couple of years ago but I haven't used them yet. I'm great for buying stuff and setting aside because I plan to work on something but other stuff becomes more important so it goes on the back burner..... This being one of them. I had planned on dusting the tops of logs of soap with it for a touch of shimmer. I really need to reorganize my soaping shelves..... I have what I use most often right at hand but the rest needs to be organized some as I am not sure where they are at the moment so I can't look to say what the texture is. I'll give a better look around tomorrow. We redid our floors two years ago and I still haven't found the energy for putting things back to how they were.... I battle fibromyalgia now after my pancreatic cancer surgery so I focus on certain things and worry about the rest later. But I have got to get my butt into gear and get the rest of that organized! But I'll see if I can't find them tomorrow.... http://search.wilton.com/?q=shimmer+dust
To order it off wiltons site is the same price as stores I think..... and they have cheap shipping. I have bought some items off Wilton for baking real food to my children's delight! But I bought the shimmer dust in Michael's the craft store. They also have online coupons you can print out I think from emails if you register for them. I don't live close to one so I rarely get there, so I stopped the emails because I never looked at them.
Personally if I wanted to add shimmer to a lip balm I would not use a "glitter" of sorts. But would used a powdered colorant that had shimmer to it naturally.
Such as one from these pages. All these listed on this link are lip safe. http://www.tkbtrading.com/category.php?category_id=35
TKB does offer reasonable shipping charges, even on small orders.
I added 20 sample packs of colorants (6 grams each) and shipping was still at their lowest charge of $3.50 so that's great...... You won't need much to add a bit of shimmer....
I've not ordered from this supplier myself (yet) but i have LOTS of soaping friends who do and have on a regular basis. They use their colorants for all kinds of cosmetic projects! They are great to order from!
*sigh* I may now have to order some and play with coloring lip balms for my girls.... and myself of course!