Using PVC as a soap mold

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seaysoap

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I have always used a soap box and want to make some round bars. Anyone have any advice on using PVC? I am guessing that I just need to grease it down real good? Can I cap both ends or does it need to be able to vent?
 

morsedillon

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PVC works great for round soap molds. You'll want to make sure that the inside is clean and free of burrs so that you don't get a gouge down the side of your soap when you demold.

PVC caps like you buy at Lowe's, HD, and the like are rounded, so unless you build a frame for the pipes to sit down in they're going to tip over. I have also on occasion used other things to cap the bottom instead. My favorite is to pour about 1/2"-3/4" of polyester casting resin (available at most hobby stores) into the bottom of a disposable cup. Then, push the end of a 2" diameter PVC pipe -- smeared inside and out with mold release -- down into it and allow it to cure. Then you have a form fitting cap that is bigger than the pipe and will allow it to stand on its own.

Of course, for the top you can use a regular PVC cap but they can be hard to remove if the pipe isn't clean. I often just cover the tops with saran wrap or the like.
 

Neil

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Cap one end flat, you can use cardboard taped. Don’t grease the inside; if you do you'll never get the soap out. Roll a piece of wax paper or freezer paper the diameter of the pipe and slide inside the pipe. After the soap Gells/or not and gets hard enough it will shink slightly, at least mine did. Then just slide the soap out and cut it. I did it a couple times at first then found it most difficult to wrap round soap so I went to the more common rectangular.
 

beebiz

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If you have a Lowes close to you, you can get a flat cap for your PVC pipe. It's much easier to use than the rounded caps are. I think the flat ones are called "test" caps. Here's a link to David Fisher using a PVC pipe to make loofah soap. He has a good pic of the "test" cap that he uses to plug one end of the pipe. http://candleandsoap.about.com/od/soaprecipes/ss/loofahsoap_3.htm

Hope this helps!

Robert
 
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I haven't used the rounded ones yet, but I do use PVC downspout which is made of the same thing, just shaped like a downspout (duh - bet you didn't guess that LOL). Anyway, I don't grease it. And there is no cap for that shape so I would think that you could just cover the round one the same way I cover mine if you have a hard time finding a cap in your area. Around here you can only find them at plumbing supply warehouses. I take a piece of cheap plastic wrap about 8x8 or so and fold it in quarters so it is 4-ply. I place it across the bottom and then use duct tape to tape it up really well going in both directions (across and up and down). Just make sure that the tape is sticking to the PVC and not only the plastic. I just cover the top with a couple of pieces of duct tape and that's good enough. I also make sure it's at a pretty thick trace before I pour so that it's less likely to leak out. I place my mold between my oven and fridge and it insulates it perfectly. Mine stands up on it's own as long as no one bumps it - but otherwise I would wedge it up against a wall and place a cinder block against it. I bought one at Home Depot for cheap just for that purpose. It beats building some fancy thing for it to stand up in.

Lastly - you need to unmold them as soon as you can stick your finger in the top and it's firm. Don't let it go too long or it will be impossible to get out. Freeze it for 2 or so hours and then run hot water all around the sides of it - make sure one end is uncovered. Sometimes the heat and condensation makes it just slide out all on its own. Otherwise, make something with a rounded end (maybe a juice can or something) and put a piece of wood or something hard inside and push it out. If it's REALLY stubborn and is getting squished, let it sit a little longer and let condensation build inside. Once it's out, I usually let it sit about 24 hours on my counter and dry up a bit before I slice it. Voila! Beautiful bars.

SIDE NOTE: If it was frozen all the way through, you will HAVE TO make sure you give it a day before you cut it - even if it seems firm enough. I made the mistake of thinking it was firm, but really it was frozen and each bar cracked as I cut it. Smelled good though! LOL
 

Becky

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Round 80 mm PVC pipe is all I use for molds at the moment. I line them with scrap laminating plastic (look for a store that laminates posters and ask them for offcuts). For the bases, I bought 80mm PVC caps to fit the pipe and cut a round of plastic to fit inside them.

When you are ready to unmold, you just take off the cap, slide the log out of the pipe and unwrap it from the plastic.
 

corrine025

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soap looks greasy

I just made 3 different soaps using 3 inch pvc pipe. Im curious if any of your soaps look kinda oily when you unmold them. I lined with parchment paper, didnt have much trouble getting the soap out but when I unwrapped it from the paper it looks a little greasy. Im gonna let it sit for another day before cutting but Im wondering if this is normal?
 

Lindy

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I use PVC pipe as well and line with freezer paper. Works a charm. Don't use wax paper as it melts and become wet & sticky....
 

goteeguy

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I ONLY use PVC piping for molds. I cover the "bottom" end with cling wrap followed by a flat cap (available at Lowes). I usually give the molds a quick spritz with cooking oil before pouring. To help remove the soap more easily, place the molds in a pre-heated oven (on its lowest setting) for a pprox. 5-10min, and the soap will slide right out. I do this every week.
 

Miz Jenny

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Or you can order 3" pvc pipe bags from Chestnut Farms. Just remember to keep tamping down the pipe to keep from causing wrinkles. DH cut thin sheets of acetate to fit my pipes and if I'm using the 3rd one I use a bag. You still have to put some over the bottom. I use plastic wrap covered with an end cap and plastic wrap secured with a rubber band I also spray the stop with alcohol to keep ash from forming. I love my round soaps but also enjoy swirly bumpy tops! BTW, much easier to pour at light trace and I unmold the next day and cut a couple days after that. Y'all's MMV. :-D
 

RogueRose

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I'm trying to us the bottom of wax coated dixie cups as they fit over or inside various sizes of pipes and they make many sizes of cups. I think the plastic cups may be useful as well.

To hold the cap in place I suggest a small bead of hot glue, strong enough to hold while it is needed and then can be pealed off.

I get a little paranoid about the bottom falling off if using something that isn't meant to be a pipe cap. I'd suggest wrapping some plastic wrap around the cap as well and secure with a rubberband.
 

kmarvel

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I have always used a soap box and want to make some round bars. Anyone have any advice on using PVC? I am guessing that I just need to grease it down real good? Can I cap both ends or does it need to be able to vent?
I use Pringle Cans. They work great!!! Just peel it off the soap and cut them!
 

Candybee

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I use pringle cans for my shaving soaps and PVC pipes for my beer soap. I line them with either freezer wrap or one of those thin plastic flexible chopping mats from the dollar store.

I opted for the cappers for the PVC pipes. They are dirt cheap so I get them for both the top and bottom. I use the phalange piece that the pipe stands up on. You just pop the pipe right into the phalange and it stands up straight. Got my PVC pipe, the phalange, and cappers at Lowes. Made 4 molds for under $15. Now that is a bargain when it comes to soap molds!
 

countymounty22

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kaymarvel and Candybee have the best ideas. I take a pringles can and cut the bottom out of it. The top becomes the bottom using the lid it comes with. Take a chopping sheet/dough sheet and roll it up. I use packing tape to tape the inside seam so it wont show up in your soaps and so you can pour higher than the can without leakage.
 

Dianae

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Hi everyone, I would like to add on to this thread and share my concern about using polyvinyl chloride (PVC) plastics. I’m not a chemist nor an authority on the subject, but I just want to share and promote safety with your soap making process. I took a local soap class last month and was a bit shocked when I learned PVC could be used as a soap mold. I heard long ago from a plumber working on my home that PVC is a dirty plastic. So I researched and it wasn’t hard to learn that just like bisphenol A (BPA), there are hazards to using these in our daily lives. I know it’s impossible to remove 100% of hazardous material from our lives, but this is one that can be avoided. As saponification is a chemical reaction, it may adversely interact with the material used in the PVC and leech into your final product. Please reference www.epa.gov for further details. Here is an excerpt:

“Most vinyl chloride is used to make polyvinyl chloride (PVC) plastic and vinyl products. Acute (short-term) exposure to high levels of vinyl chloride in air has resulted in central nervous system effects (CNS), such as dizziness, drowsiness, and headaches in humans. Chronic (long-term) exposure to vinyl chloride through inhalation and oral exposure in humans has resulted in liver damage. Cancer is a major concern from exposure to vinyl chloride via inhalation, as vinyl chloride exposure has been shown to increase the risk of a rare form of liver cancer in humans. EPA has classified vinyl chloride as a Group A, human carcinogen.”
 

DeeAnna

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"...Acute (short-term) exposure to high levels of vinyl chloride... Chronic (long-term) exposure to vinyl chloride... Cancer is a major concern from exposure to vinyl chloride... EPA has classified vinyl chloride..."

@Dianae -- Why are you equating polyvinyl chloride (PVC) with vinyl chloride???? They are NOT the same thing and they do NOT have even close to the same level of risk. If you have concerns about the use of PVC, then please share them (in a new thread preferably), but please don't conflate the two chemicals.

PVC is resistant to alkalis, so it is chemically safe for use with soap batter as long as the PVC container or pipe is sturdy and is not exposed to high temperatures (PVC softens when temps are above about 150 F).

***

Welcome to SMF, Dianae. Please introduce yourself in the Intro forum and tell us a little about yourself.
 

Dianae

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"...Acute (short-term) exposure to high levels of vinyl chloride... Chronic (long-term) exposure to vinyl chloride... Cancer is a major concern from exposure to vinyl chloride... EPA has classified vinyl chloride..."

@Dianae -- Why are you equating polyvinyl chloride (PVC) with vinyl chloride???? They are NOT the same thing and they do NOT have even close to the same level of risk. If you have concerns about the use of PVC, then please share them (in a new thread preferably), but please don't conflate the two chemicals.

PVC is resistant to alkalis, so it is chemically safe for use with soap batter as long as the PVC container or pipe is sturdy and is not exposed to high temperatures (PVC softens when temps are above about 150 F).

***

Welcome to SMF, Dianae. Please introduce yourself in the Intro forum and tell us a little about yourself.
Well I can’t argue with a subject matter expert. I knew the difference between VCs and PVC plastics and should’ve stated it more clearly, but you did it nicely and am glad you did. At least for me, I just can’t bring myself to use it yet.
 

Noreen Moore

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I still line my PVC pipe with freezer paper. I like to think the freezer paper protects the soap per se. A dab of Vaseline on the pipe holds the paper pretty good too. The caps seal them nicely on the bottom with saran wrap inside as well. I love my round Soaps!
 

Dianae

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I still line my PVC pipe with freezer paper. I like to think the freezer paper protects the soap per se. A dab of Vaseline on the pipe holds the paper pretty good too. The caps seal them nicely on the bottom with saran wrap inside as well. I love my round Soaps!
Good idea ;) Right now I’m looking at everything as a possible mold and imagining the possibilities for shapes. I saw another soaper mention the same thing and thought it was funny because I caught myself doing the same ;D I bet your soaps look so pretty!
 
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