Build a soap recipe in the calculator

Build a soap recipe in Kerno's calculator and approve it for production. A formulation is the recipe behind a product: its oils, lye, water and additives, calculated and checked. Once a version is approved, you can create the BOM that production uses.

Build the recipe

1. Go to Formulations and click New formulation.
2. Type a name in Name your recipe. You can rename it later from the top of the calculator.
3. Under What are you making?, choose Soap. It covers cold and hot process bar soap (NaOH) and liquid soap paste (KOH).
4. Under How do you want to build it?, choose Guided to go one section at a time, or Full page to see everything at once. You can switch at any time.
5. Click Start recipe.
6. In Set up your recipe, choose NaOH for bar soap or KOH for liquid soap, whether you enter oils as percentages or weights, and how pure your lye is. Kerno's default purity is 99.8%.
7. In Oils, click Add oils or one of the Popular oils, then give each oil its share. Enter the total in How much oil in total? and pick the unit.
8. Click Next and set the superfat and water in Superfat and water.
9. In Additives, click Add additives and pick fragrance, color, clays or milks. Kerno fills in the usual amount, the stage it goes in and any handling notes. Change the amount or unit, such as % of oils or g per batch, on each line.
10. Add any notes or photos in Notes and photos, then click Next.
11. In Approve, read anything under Is it ready to approve?, then click Approve recipe.

The recipe shows Approved · v1, and Create BOM appears at the top. Production uses the approved version.

What the calculator shows

• Lye calculation shows the lye to weigh, the water, the oils and the batch weight. It appears once your oils total 100%.
• Soap properties rates hardness, longevity, cleansing, conditioning, lather, creaminess, iodine and INS against the usual ranges. The ranges are guidance only.
• Tune the blend lets you try another oil blend side by side.
• Every change saves as you go.

The recipe toolbar

The buttons along the top of a recipe:

• Guided and Full page switch how the calculator is laid out.
• Show tips turns the calculator's tips on, and Hide tips turns them off again.
• Save as template saves the recipe as a template you can start new recipes from.
• Share sends a read-only link or shares the recipe with the Kerno community. See Share a recipe with a link or the Kerno community.
• Print prints the recipe sheet on one page. Choose what goes on it: Recipe photo, QR code to the approved version, Soap properties and fatty acids and Recipe notes. Uncheck the last two for a plain weighing sheet.
• The three dots open the More menu.

An approved recipe also shows Print the recipe sheet, Share with the Kerno community and Save as a template under its approval.

The More menu

• Versions lists each version with its status, batch, cost and approval, and the BOMs made from the recipe. New version starts another one.
• History lists every status change of every version, newest first.
• Calculation record shows how a version was calculated: the engine and its version, when and by whom, the currency, the inputs hash that approval uses to check the saved inputs still match, and the record id. Method writes out the equations behind the lye, water, additives and soap properties.
• Copy recipe creates a new recipe with the same oils, additives and settings, as a draft version 1.0. Name the copy and keep its product or pick another. The original doesn't change.
• Add photo adds a photo of the recipe: PNG, JPG or GIF, up to 2 MB each and up to 8 photos. The main photo prints on the recipe sheet.
• Archive recipe takes the recipe out of the list. Show archived on the Formulations page brings archived recipes back into view.
• Delete recipe is grayed out once a recipe has a BOM or a production batch. Archive it instead.

Good to know

• Approving locks the version for production. Change anything afterward and Kerno starts version 2 as a draft. Version 1 stays approved until you approve the new one.
• Approving also records that you read the handling notes for any additive that needs special mixing.
• With A second person approves recipes turned on in Settings, Workspace, recipes go to a teammate for approval instead of being approved by the person who wrote them.
• To start from a saved recipe, pick it in Start from a saved template. Save one from any recipe with Save as template.
• Product is optional when you start. You need it only when you create the BOM.
• Not built yet: Skincare, Makeup and Food recipes. Tell us if you need one of these.

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