Ziploc Bags Lye Safe?

[BrewerGeorge]

I've used ziploc bag for piping, so I know it's somewhat safe, but what do you think about using a ziploc bag for a soap mold?

Sounds a little crazy, I know but I've had a few people ask me about making soap and the mold is always something of a challenge for first-timers. Lots of cooks already have a stick blender that they can press into service for a first try, but very few people going to have a suitable mold. I know all the things that can be impromptu molds, of course, or lined with Walmart bags and such, but I keep going back to that gallon ziploc bag...

If you were to take batter to a thick, pudding-like trace and spoon it into a gallon ziplock, get most of the air out and seal (one of the slide-seal would probably be best) I think it would flatten out into a slab shape. With 500-700 grams of oils you'd get 9 bars about 3.5 x 3.7" and "soap" thickness. Obviously corners and edges would be a little thin and pointy, but in general they'd feel like bars of soap, maybe more than some of the alternatives like a yogurt container. And unmolding would be as simple as cutting the bag off.

But how do you think the saponification process would go in a truly sealed bag, and is that plastic safe for 2 or 3 days contact?

I wonder if you could even mix up the soap inside the bag? Supported, of course.

 

[lenarenee]

Any way of knowing if Ziploc bags are a 2 or a 5?

If not, I'd worry about prolonged contact of soap batter. With piping, the batter is partly saponified by the time its set up enough to pipe. And if you use a fo that heats that adds to the risk.

 

[BrewerGeorge]

It's polypropylene so #5, I guess.

 

[penelopejane]

I've used ziploc bag for piping, so I know it's somewhat safe, but what do you think about using a ziploc bag for a soap mold.

If you were to take batter to a thick, pudding-like trace and spoon it into a gallon ziplock, get most of the air out and seal.

I wonder if you could even mix up the soap inside the bag? Supported, of course.

BrewerGeorge,
The bag will survive but the soap won't cure in there. That's how you keep batter pliable to make soap dough. You'd take it out after a day (or keep it for weeks like that) and roll it to make shapes. Maybe you could cut it into bars if you wanted to.

Pringles and milk cartons make great molds for first timers.

 

[BrewerGeorge]

Good to know, PJ.

 

[Kamahido]

BrewerGeorge,
The bag will survive but the soap won't cure in there. That's how you keep batter pliable to make soap dough. You'd take it out after a day roll it to make shapes. Maybe you cut it into bars if you wanted to.

Pringles and milk cartons make great molds for first timers.

A Pringles can was my first mold.

 

[Kittish]

Ziploc bags (and other sandwich bags) are made with a product known as “film” in the recycling industry. Film is clear, thin plastic made of either low-density polyethylene (or LDPE, which corresponds to the recycling #4) or high-density polyethylene (or HDPE, which corresponds to the recycling #2).

I'd stick with recommending a paper milk or juice carton for an impromptu mold for a first timer. And penelopejane is right about the soap not hardening in a closed plastic bag. I lined my mold with an oven bag for the soap dough I made recently, then closed the bag up once I had the soap poured. Let it sit for two days, and the soap was still quite squishably soft. It needed another day after I took it out of the bag to firm up.

 

[dixiedragon]

I've done it and it worked fine. You could use it as a sort of liner in a glass to metal container.

 

[Susie]

I've used Ziploc bags for mold liners for a number of batches before I got real molds. They work well, can be washed and re-used, even.

 

[MarlaKC]

My first molds were paper drink cups. Each made three graduated size round soaps. Then graduated to fruit cups and cat food containers.

 

[BrewerGeorge]

BrewerGeorge,
The bag will survive but the soap won't cure in there. That's how you keep batter pliable to make soap dough. You'd take it out after a day (or keep it for weeks like that) and roll it to make shapes. ..

.. And penelopejane is right about the soap not hardening in a closed plastic bag. I lined my mold with an oven bag for the soap dough I made recently, then closed the bag up once I had the soap poured. Let it sit for two days, and the soap was still quite squishably soft. It needed another day after I took it out of the bag to firm up.

Is that all I have to do to make soap dough? Seal it up? Is that true even with an accelerating fragrance?

I know I'm a month late, but I'm going to make a soap that looks like turquoise in its matrix. The scent is accelerating and discoloring, so I'm planning on it being the matrix and coloring an unscented portion blue for the turquoise.

I've been pondering how to best do this, and it occurs that soap dough might be a good fit. Especially if all I have to do is seal it in a bag during saponification...

 

[penelopejane]

Is that all I have to do to make soap dough? Seal it up? Is that true even with an accelerating fragrance?

I know I'm a month late, but I'm going to make a soap that looks like turquoise in its matrix. The scent is accelerating and discoloring, so I'm planning on it being the matrix and coloring an unscented portion blue for the turquoise.

I've been pondering how to best do this, and it occurs that soap dough might be a good fit. Especially if all I have to do is seal it in a bag during saponification...

I
Yes that's all you have to do. But it's a bit tricky.
Read sorcery soaps blogs about soap dough. You can make it from any recipe. The most important thing is pliability of the soap. Water content (29% lye concentration is what she uses full) greatly effects this. You want to be able to work it and it stays pliable without starting little cracks that show when it dries out. Might be possible to add a tiny bit of water to keep it pliable - not moist.

An accelerating FO will be a challenge to a challenging process. It might speed it onto cure so it's not workable for long. Not sure how long you need to work with it. If it's a simple design it might very well work.

 

[toxikon]

My lard recipe makes excellent soap dough! I agree about using a bit more water if you usually use a discount. Not necessarily full water, but around 28-30% lye conc would do the trick.

I tend to pour any leftover batter into my cavity molds then cover in plastic wrap over night. In the morning I roll my new soap dough into a ball, cover tightly with the plastic wrap then store in balls in a larger ziploc. Stays nice and pliable for a long time.

 

[jbedaded]

molds

I've used yogurt cups

 

[earlene]

MarlaKC, that's quite smart. I recently ended up with a plastic drinking cup as a mold because it hardened too quickly to color and pour from the multiple cups. It became 3 round puck-like soaps with the little lines from the cup. I can see this as a perfect mold for beginners. The only trouble I had was trying to cut them straight because of the graduate shape of the sides of the cup.

 

[Kittish]

Is that all I have to do to make soap dough? Seal it up? Is that true even with an accelerating fragrance?

I know I'm a month late, but I'm going to make a soap that looks like turquoise in its matrix. The scent is accelerating and discoloring, so I'm planning on it being the matrix and coloring an unscented portion blue for the turquoise.

I've been pondering how to best do this, and it occurs that soap dough might be a good fit. Especially if all I have to do is seal it in a bag during saponification...

What I did with mine, when I started working it, was split the dough, and put each piece in a separate bag and worked a little bit of oil into it (this was to mix the color in, granted, but...). It made the dough a lot softer and more pliable, and if you set your SF a bit lower than usual to account for the additional oil, then I don't see why you couldn't use the trick just to make the dough easier to work, if it's stiffer than you wanted. Doesn't appear to take much, I added about a teaspoon each to the quarters I split my pound of dough into (slightly over 1 tablespoon total of extra oil).