Soap Wont Cut Smoothly

[MellonFriend]

I made a batch of soap about 36hrs ago and I can't seem to get it to cut cleanly. Every time I get the knife about 3/4 of the way through the bar, it sticks to the knife and breaks off. I don't understand it. The one bar sort of broke in half after I cut it. It's not like the bar is hard yet, the knife goes right through it. Am I just not waiting long enough to cut it? Did I wait too long? Could it be a recipe thing? I can post it if that would help.

Edit to add recipe:

I was soaping at around 86-96* for my lye solution and oils respectively. I don't know if this is a factor, but I did notice that my FO seemed to decelerate my trace. The FO isn't listed on the recipe, but it was 45g of Crafters choice Lavender & Mint. The soap did gel.

 

[TheGecko]

It's not like the bar is hard yet, the knife goes right through it. Am I just not waiting long enough to cut it?

I think you answered your own question. I live in the Pacific Northwest of the US...it's damp and chilly this time of year so I usually give my loaf molds 48 hours before unmolding and then let the soap sit out for couple of hours before cutting (I use a wire cutter) or even the next day. I also double up on my Sodium Lactate. Curing also takes a bit longer, but I'm in no rush.

 

[Obsidian]

You are probably waiting too long and its possibly your knife blade it too thick.
If the spine is thick, it acts like a wedge and breaks soap.
Get a really thin knife or even better, a wire cheese cutter

 

[MellonFriend]

You guys just contradicted each other.

I just powered through and cut the rest of the bars. I "invented" a soap cutter by tying fishing line between two clothes pins and that got the job done. The knife I was using was the same knife I always have used in the past without issue. I have always in the past been able to cut my soap at 12-24 hours, but this was a new recipe so maybe it was just different.

 

[Obsidian]

There can be a lot of reasons soap doesn't cut cleanly. For me, the bars only break like that when the soap is too hard. If its soft, it crumbles differently.
Glad you came up with a solution to cut the rest.

 

[cmzaha]

You guys just contradicted each other.

I just powered through and cut the rest of the bars. I "invented" a soap cutter by tying fishing line between two clothes pins and that got the job done. The knife I was using was the same knife I always have used in the past without issue. I have always in the past been able to cut my soap at 12-24 hours, but this was a new recipe so maybe it was just different.

Obsidian is correct that there are various reasons a soap does not cut cleanly. I am with her that the only time I would get that type of breakage, even with my multi-cutter is when the soap was too hard, but too soft can also stick to the knife and take out chunks. So it really is hard to say, which is why the contraction in opinions. You simply cannot just depend on the time when factoring in when to cut, the feel of the soap is important. This one actually looks like it might have still been too wet.

 

[MellonFriend]

My instinct was that it was not yet hard enough, but I just wanted to be sure there wasn't something I was missing. I can see that it could be a lot of things. I guess it's just another mystery of soap making that I'll have to figure out by trial and error. Thanks everyone for the advice!

 

[TheGecko]

You guys just contradicted each other.

No really. Soap making isn't a one-size-fits-all kind of deal...different people experience different things.

 

[MellonFriend]

No really. Soap making isn't a one-size-fits-all kind of deal...different people experience different things.

I completely understand. I just found it ironic.

 

[melinda48]

I think you answered your own question. I live in the Pacific Northwest of the US...it's damp and chilly this time of year so I usually give my loaf molds 48 hours before unmolding and then let the soap sit out for couple of hours before cutting (I use a wire cutter) or even the next day. I also double up on my Sodium Lactate. Curing also takes a bit longer, but I'm in no rush.

You answered your own question. It never hurts to wait longer (unless it is salt soap).

 

[Susie]

When I switched to this cutter, all of my problem cuts ended: https://smile.amazon.com/PH-PandaHall-Cutting-Candles-Trimming/dp/B089DHSXGF/ref=sr_1_57?crid=3I1A31J6H2LWE&keywords=soap+cutter&qid=1647091578&sprefix=soap+cutter,aps,93&sr=8-57

But I was also much more experienced by then, so I knew when to cut and when to wait. I do the "press one corner of the mold to check for firmness" method of determining the timing.

 

[MellonFriend]

When I switched to this cutter, all of my problem cuts ended: https://smile.amazon.com/PH-PandaHall-Cutting-Candles-Trimming/dp/B089DHSXGF/ref=sr_1_57?crid=3I1A31J6H2LWE&keywords=soap+cutter&qid=1647091578&sprefix=soap+cutter,aps,93&sr=8-57

But I was also much more experienced by then, so I knew when to cut and when to wait. I do the "press one corner of the mold to check for firmness" method of determining the timing.

Oooo that looks like a nice cutter. Thanks for the suggestion!

 

[Mobjack Bay]

What trace stage was your batter?

This may not apply, but I’ll chime in because it hasn’t been mentioned above. As I continue to refine the methods for my recipes, which include working at a high lye concentration, making small batches (400-1000 g oils) and keeping coconut oil on the low side (< 20%), I‘ve found that I‘m more likely to end up with grainy soap when I start cool (< 90F) and the batter is at emulsion rather than light trace. This is even after gelling. In my world, it’s a small batch, low coconut, working at emulsion phenomenon that the low coconut/larger batch soapers may not encounter routinely. My solution for producing good soap using small batches of batter at emulsion, and for my recipes, has been to work warmer. I start with oil and lye temps that yield >95F when first mixed. After 2-3 quick pulses with the sb and some stirring to ensure that everything is mixed in from the edges and bottom, I watch what happens. If I get a temperature jump, I know I can split the batter and proceed with the design. If the batter is too thin for the design, I blend a little more when the colorants and FO or EOs are added. The increase in the starting temperature of the batch hasn’t been a problem, perhaps because I stay away from accelerating scents. On the flip side, I recently went through trial size bottles of OT’s Green Tweed and Bonsai. Both seemed to decelerate and I had to sb more than usual at the beginning.

 

[MellonFriend]

Well it sounds like you pretty much just described what I was trying to do. ☺ Low coconut oil/working at emulsion/not soaping at a high temp/800g batch. Also I think my fragrance oil decelerated the batter too. I'll be sure to keep all that in mind next time. Thanks so much for the insight!

 

[TheGecko]

What trace stage was your batter?

This may not apply, but I’ll chime in because it hasn’t been mentioned above. As I continue to refine the methods for my recipes, which include working at a high lye concentration, making small batches (400-1000 g oils) and keeping coconut oil on the low side (< 20%), I‘ve found that I‘m more likely to end up with grainy soap when I start cool (< 90F) and the batter is at emulsion rather than light trace. This is even after gelling. In my world, it’s a small batch, low coconut, working at emulsion phenomenon that the low coconut/larger batch soapers may not encounter routinely. My solution for producing good soap using small batches of batter at emulsion, and for my recipes, has been to work warmer. I start with oil and lye temps that yield >95F when first mixed. After 2-3 quick pulses with the sb and some stirring to ensure that everything is mixed in from the edges and bottom, I watch what happens. If I get a temperature jump, I know I can split the batter and proceed with the design. If the batter is too thin for the design, I blend a little more when the colorants and FO or EOs are added. The increase in the starting temperature of the batch hasn’t been a problem, perhaps because I stay away from accelerating scents. On the flip side, I recently went through trial size bottles of OT’s Green Tweed and Bonsai. Both seemed to decelerate and I had to sb more than usual at the beginning.

This. It's why it is so important to develop a good recipe and get to know it. I was out there in the wilds the first few months I was making soap (hadn't found you all yet) making 50oz batches of this and that one time and this and that another time and then stuff would happen and given everything that can affect your soap, I had no clue what I was doing wrong (or right)...until I settled down with a single recipe and started making 20oz batches. Even something as simple as going from making soap completely from scratch to Master Batching can have an affect on your soap making.

 

[SurfSoaper]

You guys just contradicted each other.

I just powered through and cut the rest of the bars. I "invented" a soap cutter by tying fishing line between two clothes pins and that got the job done. The knife I was using was the same knife I always have used in the past without issue. I have always in the past been able to cut my soap at 12-24 hours, but this was a new recipe so maybe it was just different.

@MellonFriend I know this is an older post, but do you remember what type of fish line you used? Either the diameter of the lb size? Thank you!

 

[MellonFriend]

@MellonFriend I know this is an older post, but do you remember what type of fish line you used? Either the diameter of the lb size? Thank you!

Hey there, I'm sorry, I have no idea what the type of line was. I had an old spool that I had been using for various things around the house and it finally ran out a little while ago, so I'm not sure what it was. I got myself a cheap wire soap cutter off amazon for soap cutting and I've been using that ever since.

 

[SurfSoaper]

Oh, Okay. Thanks for letting me know! I'll just go and browse and see what looks good. Thanks again!