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I’ve been on a bit of a slab mold journey over the last three years and learned a few things along the way that I detailed below in case anyone else is thinking about buying a slab mold. Early on I was always looking for small slab molds because I typically don’t make soap with more than 1000 g of oils. Over time, I developed a preference for bars that are 2,5”x3.5” in size and I want minimal cutting waste. Many slab molds won’t tick all three of these boxes.

The first slab mold to join my collection was a cardboard candy box, which is a great way to go if you’re new to soap making. Then I added my trusty 6”x6” silicone mold. These are easy to find and made of very durable silicone. I’ve gotten a lot of mileage out of that little mold, love that it doesn’t have to be lined and still use it to make four 3” square or six 2”x3” bars. Next up was the bottom tray for a slatted wooden bread cutting board that I found at a thrift store for about 99 cents. It works well, but is shallow and I have to line it with freezer paper.

8B2DD55B-D58E-473F-91F3-8350B8C8D27A.jpeg

Next I bought the blue silicone loaf mold in the photo below. It was relatively inexpensive and works well for slab-like single layer wall pours along the long wall. The interior dimensions are close to 5”x 10+”, which yields eight bars that are close to 2.5”x3.5”. On the downside, the mold is a bit floppy, which makes it tricky to tilt and to move. There’s also not a lot of working room for a design like a cosmic swirl and it’s not a good shape for a spin swirl. The soft sides don’t distort for a single layer soap, but they bow out when the loaf is filled to the top (2.5” depth). I’ve used a lego crate to cradle this mold, but a wood box would be even better and making one is still on my to-do list. The divided wood mold was a Christmas present last year. Honestly, I only used it once and without the dividers, partly because I do not like lining molds. At 1.5” depth, it’s a bit shallow to tilt, which is something I like to do to get the soap to move across the mold when I’m doing a wall pour in a slab mold. I personally wouldn‘t try to use it for a spin switl because I can be messy. Using the dividers would yield nine bars that are a hair over 2”x3”. They are a bit wonky looking, but might stay straight in a full mold. I made eight 2.5”x3.5” bars and some smaller pieces by following the black marks I put on the sides.

1F4E3F3C-49CE-4C63-8CD1-B14A803CC967.jpeg

Next(?) I bought a pricey acrylic mold (5”x7” by 3+” deep) with a silicone liner. It works really well for making four or eight 2.5”x3.5” bars and is easy to tilt. I love that I can see through the side of the mold to get an idea how the colors and layering are playing out below the surface. The liner is flexible but sturdy and it’s easy to get the soap out even when I make eight bars. It’s one of my favorite molds overall. On the downside, the combo of smallish interior dimensions and reasonable height of the mold makes it very challenging to pour close to the surface of the soap when I’m making four bars. I bought the relatively inexpensive 10+” square silicone mold to make column pour soaps for a recent SMF Challenge. It’s a bit flimsy due to size, but a cutting board takes care of that problem. I wouldn’t try to use it for a spin swirl since it’s only 1.5” deep, but I expect it will be really easy to work a design close to the soap surface in this mold and it’s a great size for the pipe divider swirl. It makes twelve bars that are close to 2.5”x3.5”. It’s not a mold I will use regularly due to the size, but it’s good to have on hand.

D316C6E3-2AC1-4300-99AD-1834E20C56DC.jpeg

Last but not least, here’s my newest mold. With the dividers it yields nine 2.5”x3.5” bars that can be up to 2.5” tall. I plan to fill it to 1.5” depth to leave some room for planing the soap tops. With interior dimensions just under 8”x11”, it should give me the room I need for pouring close to the soap and it will also be easy to tilt. It’s also plenty high enough to do a spin swirl without sloshing soap out of the mold. A consideration with dividers is the resultant smear pattern on the side of each soap, but I also have the option of not using the dividers. I‘m hoping that I won’t have an issue separating the soap from the dividers based on the amount of hard oils and butters in my recipes. I may give this mold a trial run tomorrow. Please keep your fingers crossed that I don’t lose my mind and add an accelerating FO Into the mix!

681CC219-2F88-4075-A734-DAE5E662515C.jpegEF910E95-EAFB-42F3-8439-0BCB08A858C2.jpeg
 
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Last but not least, here’s my newest mold. With the dividers it yields nine 2.5”x3.5” bars that can be up to 2.5” tall. I plan to fill it to 1.5” depth to leave some room for planing the soap tops. With interior dimensions just under 8”x11”, it should give me the room I need for pouring close to the soap and it will also be easy to tilt. It’s also plenty high enough to do a spin swirl without sloshing soap out of the mold. A consideration with dividers is the resultant smear pattern on the side of each soap, but I also have the option of not using the dividers. I‘m hoping that I won’t have an issue separating the soap from the dividers based on the amount of hard oils and butters in my recipes. I may give this mold a trial run tomorrow. Please keep yor fingers crossed that I don’t lose my mind and add an accelerating FO Into the mix
Please share your experience! I've been looking at one of their molds and would love to see some feedback!
 
I’ve been on a bit of a slab mold journey over the last three years and learned a few things along the way that I detailed below in case anyone else is thinking about buying a slab mold. Early on I was always looking for small slab molds because I typically don’t make soap with more than 1000 g of oils. Over time, I developed a preference for bars that are 2,5”x3.5” in size and I want minimal cutting waste. Many slab molds won’t tick all three of these boxes.

The first slab mold to join my collection was a cardboard candy box, which is a great way to go if you’re new to soap making. Then I added my trusty 6”x6” silicone mold. These are easy to find and made of very durable silicone. I’ve gotten a lot of mileage out of that little mold, love that it doesn’t have to be lined and still use it to make four 3” square or six 2”x3” bars. Next up was the bottom tray for a slatted wooden bread cutting board that I found at a thrift store for about 99 cents. It works well, but is shallow and I have to line it with freezer paper.

View attachment 67640

Next I bought the blue silicone loaf mold in the photo below. It was relatively inexpensive and works well for slab-like single layer wall pours along the long wall. The interior dimensions are close to 5”x 10+”, which yields eight bars that are close to 2.5”x3.5”. On the downside, the mold is a bit floppy, which makes it tricky to tilt and to move. There’s also not a lot of working room for a design like a cosmic swirl and it’s not a good shape for a spin swirl. The soft sides don’t distort for a single layer soap, but they bow out when the loaf is filled to the top (2.5” depth). I’ve used a lego crate to cradle this mold, but a wood box would be even better and making one is still on my to-do list. The divided wood mold was a Christmas present last year. Honestly, I only used it once and without the dividers, partly because I do not like lining molds. At 1.5” depth, it’s a bit shallow to tilt, which is something I like to do to get the soap to move across the mold when I’m doing a wall pour in a slab mold. I personally wouldn‘t try to use it for a spin switl because I can be messy. Using the dividers would yield nine bars that are a hair over 2”x3”. They are a bit wonky looking, but might stay straight in a full mold. I made eight 2.5”x3.5” bars and some smaller pieces by following the black marks I put on the sides.

View attachment 67645

Next(?) I bought a pricey acrylic mold (5”x7” by 3+” deep) with a silicone liner. It works really well for making four or eight 2.5”x3.5” bars and is easy to tilt. I love that I can see through the side of the mold to get an idea how the colors and layering are playing out below the surface. The liner is flexible but sturdy and it’s easy to get the soap out even when I make eight bars. It’s one of my favorite molds overall. On the downside, the combo of smallish interior dimensions and reasonable height of the mold makes it very challenging to pour close to the surface of the soap when I’m making four bars. I bought the relatively inexpensive 10+” square silicone mold to make column pour soaps for a recent SMF Challenge. It’s a bit flimsy due to size, but a cutting board takes care of that problem. I wouldn’t try to use it for a spin swirl since it’s only 1.5” deep, but I expect it will be really easy to work a design close to the soap surface in this mold and it’s a great size for the pipe divider swirl. It makes twelve bars that are close to 2.5”x3.5”. It’s not a mold I will use regularly due to the size, but it’s good to have on hand.

View attachment 67647

Last but not least, here’s my newest mold. With the dividers it yields nine 2.5”x3.5” bars that can be up to 2.5” tall. I plan to fill it to 1.5” depth to leave some room for planing the soap tops. With interior dimensions just under 8”x11”, it should give me the room I need for pouring close to the soap and it will also be easy to tilt. It’s also plenty high enough to do a spin swirl without sloshing soap out of the mold. A consideration with dividers is the resultant smear pattern on the side of each soap, but I also have the option of not using the dividers. I‘m hoping that I won’t have an issue separating the soap from the dividers based on the amount of hard oils and butters in my recipes. I may give this mold a trial run tomorrow. Please keep yor fingers crossed that I don’t lose my mind and add an accelerating FO Into the mix!

View attachment 67650View attachment 67649
Wow! That last one is a bit flash.
 
Please share your experience! I've been looking at one of their molds and would love to see some feedback!
I’ve seen good reviews for this company’s molds in various threads so I’m expecting it to work well. The quality seems excellent. I went for the upgrade to an oil finish and also bought the top. I’m sure hoping this is the one.
Wow! That last one is a bit flash.
✨
 
I’ve seen good reviews for this company’s molds in various threads so I’m expecting it to work well. The quality seems excellent. I went for the upgrade to an oil finish and also bought the top. I’m sure hoping this is the one.

✨
I have that mold, and love it. Just be sure to wipe a thin layer of Vaseline on the dividers so the soap is easier to remove. I forgot once and had to take a wire between the divider and the soap to get it out. 🙁
 
The slab mold has soap in it! I managed to slop a little over the edges, but otherwise all went well and with 35% palm no less. I was nervous about messing up a lot of soap, but also really wanted to use up the palm that’s been sitting around. The trace wasn’t thin enough to do a fine peacock swirl, so I did one with wider spacing and then added a DNA/helix swirl.

D1A49DCF-9368-426C-99D3-FC94417C8488.jpeg
 
Here are the bars out of the mold. The bars were fairly easy to remove from the dividers even though I didn’t use mineral oil. For context, the recipe is 30% stearic + palmitic, I used 40% lye concentration, soap gelled and I unmolded at around 18-20 hours. I did a very quick pass to clean up the edges and overall ended up with very little waste. 95% of the original batter weight is in the bars and an additional 3% is in trimmings and the little soaps in the photo below. The bars weigh between 5.5 and 6 oz. each. The heaviest one was from the center of the mold.

6F91DC3A-FC94-4EB2-A6A2-6DBFBDBFBB4C.jpeg
627E502A-B6B5-49AE-B366-8ADFDDD28657.jpeg
 
Those bars are just gorgeous! You have a fairly impressive slab collection, too. Is the Workshop Heritage your favorite now?
Thank you! After weeks of playing around with botanical colorants and clays I was missing the micas. This mold is fun because there’s plenty of surface area to design, but I’m still attached to most of the others for various totally defensible reasons 😂.
 
This mold is fun because there’s plenty of surface area to design, but I’m still attached to most of the others for various totally defensible reasons 😂.
Sounds like my old loom collection. I used to loom knit, not to be confused with a weaving loom, and as much as I enjoyed it...if you like to make a lot of different things, you had to buy a lot of different looms because each one was a fixed medium. I got into needle knitting and sold/gave away the majority of my loom.
 
I was just about ready to make a new post asking for slab mold advice when I found this thread. @Mobjack Bay, are you still pleased with the last slab mold you mentioned? Where did you purchase it from? I was gifted a 10" silicon slab for Christmas, and I'm considering trading it in for a smaller, more practical size.
 
I was just about ready to make a new post asking for slab mold advice when I found this thread. @Mobjack Bay, are you still pleased with the last slab mold you mentioned? Where did you purchase it from? I was gifted a 10" silicon slab for Christmas, and I'm considering trading it in for a smaller, more practical size.
The last slab mold I purchased is this one from Workshop Heritage. I use it to make 9 bars in a single layer. It’s very sturdy and well made. The interior liner bows in a teeny bit as you can see in one of the photos above, but it’s easy enough to tape to the side, or maybe add some petroleum jelly between the liner and the wood to hold it to the wood, which I haven’t tried. I love the dividers because I don’t have to cut the slab to make the bars. Most of my recipes have come out relatively cleanly within 24 hrs but for one batch I had to wait a little longer. Someone above mentioned using mineral oil to coat the dividers but I haven’t needed to try that. As a gauge, my recipes typically have 30% palmitic + stearic, coconut < 20% and I don’t use sodium lactate. I can pour complex designs in the mold using paper cups, but there’s not a lot of interior working room for my small long-spouted pitchers. The big benefit of the 10” silicone mold is the low sides. Granted, I don’t use it much because it makes 12 bars, but I’m still happy to have it. I recently used that mold to make multiple batches of soap that required complex design work. It was a breeze to get into every part of the mold using all kinds of pouring containers. I also like the 6” square silicone mold I have for the same reason, but don’t like that I can’t cut 2.5“ x 3.5” bars from a 6” square without odd pieces. The 10” mold is also great for column pours. It’s the most fun mold I have! The other slab mold I use often is from CCT. It has a 5” x 7” footprint and makes 4 or 8 bars (2.5“ x 3.5”). It‘s my practical compromise for testing designs that can be poured from a couple of inches above the soap. Plus, you can see the sides of the soap through the liner, which is a great feature. The high sides (2.5”+ ?) limit the working space for designs that need to be poured close to the surface of the soap. I keep looking for a 5“ x 7” silicone mold to replace the 6” square mold, but I don’t think there is such a thing.
 
The last slab mold I purchased is this one from Workshop Heritage. I use it to make 9 bars in a single layer. It’s very sturdy and well made. The interior liner bows in a teeny bit as you can see in one of the photos above, but it’s easy enough to tape to the side, or maybe add some petroleum jelly between the liner and the wood to hold it to the wood, which I haven’t tried. I love the dividers because I don’t have to cut the slab to make the bars. Most of my recipes have come out relatively cleanly within 24 hrs but for one batch I had to wait a little longer. Someone above mentioned using mineral oil to coat the dividers but I haven’t needed to try that. As a gauge, my recipes typically have 30% palmitic + stearic, coconut < 20% and I don’t use sodium lactate. I can pour complex designs in the mold using paper cups, but there’s not a lot of interior working room for my small long-spouted pitchers. The big benefit of the 10” silicone mold is the low sides. Granted, I don’t use it much because it makes 12 bars, but I’m still happy to have it. I recently used that mold to make multiple batches of soap that required complex design work. It was a breeze to get into every part of the mold using all kinds of pouring containers. I also like the 6” square silicone mold I have for the same reason, but don’t like that I can’t cut 2.5“ x 3.5” bars from a 6” square without odd pieces. The 10” mold is also great for column pours. It’s the most fun mold I have! The other slab mold I use often is from CCT. It has a 5” x 7” footprint and makes 4 or 8 bars (2.5“ x 3.5”). It‘s my practical compromise for testing designs that can be poured from a couple of inches above the soap. Plus, you can see the sides of the soap through the liner, which is a great feature. The high sides (2.5”+ ?) limit the working space for designs that need to be poured close to the surface of the soap. I keep looking for a 5“ x 7” silicone mold to replace the 6” square mold, but I don’t think there is such a thing.
Thanks for your amazingly comprehensive reply! When you use the 10", do you know how many ounces/grams of batter it takes to fill it?
 
Thanks for your amazingly comprehensive reply! When you use the 10", do you know how many ounces/grams of batter it takes to fill it?
I started this thread to help others with the learning curve on slab molds so I’m happy the information is useful. I will check my notes in the morning and get back to you on the capacity. I think it’s around 1800 g to make a single layer of 12 bars, calculated with 40% lye concentration.
 
I will check my notes in the morning and get back to you on the capacity. I think it’s around 1800 g to make a single layer of 12 bars, calculated with 40% lye concentration.
1800 g TBW will work, depending on how thick you want the soap bars to be and how easy it is to get all of your batter into the mold without waste. If you succeed in getting all of the batter into the mold, the bars should be about 4 oz when dry. I increased my TBW to 2170 g for a complicated design to ensure that I had enough batter to make all of the different design elements.
 

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