The Art of Soap Making

Chapter 2: The Science of Saponification

Understanding the chemistry behind soap making isn't just academic - it's the foundation for creating successful recipes and troubleshooting problems. Don't worry; you don't need a chemistry degree. The basics are straightforward and fascinating.

The Saponification Reaction

Saponification is the chemical reaction between a fat (triglyceride) and a strong alkali (sodium hydroxide for bar soap, potassium hydroxide for liquid soap). The reaction produces two things: soap molecules and glycerin.

Every fat molecule consists of a glycerin "backbone" with three fatty acid chains attached. When lye meets fat, it breaks these bonds. The fatty acids combine with sodium to form soap, while the glycerin is released as a beneficial byproduct.

This reaction is exothermic, meaning it generates heat. When you mix your lye solution with oils, you'll feel the container warm up - this is saponification beginning. The reaction continues for hours and even days, which is why soap needs curing time.

SAP Values Explained

Every oil has a specific "SAP value" (saponification value) that tells us exactly how much lye is needed to convert it to soap. This number represents the milligrams of potassium hydroxide (KOH) needed to saponify one gram of that particular fat.

For bar soap, we use sodium hydroxide (NaOH), which requires conversion from the KOH value. The NaOH SAP value is approximately 70% of the KOH value due to molecular weight differences.

Using accurate SAP values is critical. Too little lye leaves unreacted oil (a soft, possibly rancid soap). Too much lye creates a harsh, potentially caustic bar. This is why we use precise calculations and include a "superfat" percentage as a safety margin.

Understanding Superfat

Superfatting means using slightly less lye than needed to convert all oils, intentionally leaving some oil unsaponified. This serves two purposes:

• Safety margin: Accounts for measurement variations and SAP value ranges
• Skin benefits: Unreacted oils remain in the soap to moisturize skin

Most cold process recipes use 5-8% superfat. Lower percentages (3-5%) create a harder, more cleansing bar. Higher percentages (8-10%) create a softer, more conditioning bar but may reduce shelf life.

Chapter 3: Essential Equipment

One beauty of soap making is that you don't need expensive specialty equipment to begin. Most items can be found in your kitchen or purchased inexpensively. However, once designated for soap making, equipment should not return to food use.

Required Equipment

Digital Scale

Your most important tool. Must be accurate to 1 gram (0.1 gram is even better for small batches). Soap making is done entirely by weight - never by volume. A scale reading to at least 5kg capacity covers most recipes.

Mixing Containers

You'll need at least two: one for mixing lye solution, one for combining with oils. Requirements:

• Heat-resistant (lye solution reaches 200F/93C)
• Non-reactive: stainless steel, heavy-duty plastic (#2 or #5), or heat-safe glass
• Never use aluminum (reacts violently with lye) or thin plastic

Large stainless steel pots from thrift stores work perfectly. Heavy-duty plastic pitchers (like restaurant supply containers) are ideal for lye mixing.

Stick Blender (Immersion Blender)

While not strictly required (our grandmothers stirred by hand for hours), a stick blender reduces mixing time from hours to minutes. A basic model works fine - fancy features aren't needed. Dedicate it to soap making only.

Thermometer

An instant-read digital thermometer helps ensure oils and lye solution are at appropriate temperatures. Many experienced soap makers work by feel, but beginners benefit from monitoring temperatures.

Molds

Options range from free to fancy:

• Silicone loaf molds: Easy unmolding, reusable, inexpensive
• Lined wooden molds: Traditional, excellent heat retention
• Repurposed containers: Milk cartons, Pringles cans, lined cardboard boxes
• Silicone baking molds: Individual cavity molds for shaped bars

Safety Gear

• Safety goggles: Essential - lye can cause permanent eye damage
• Rubber gloves: Chemical-resistant, not thin disposables
• Long sleeves: Protects arms from splashes
• Closed-toe shoes: Protects feet from spills

Helpful Additions

• Stainless steel whisk: For initial mixing before stick blending
• Rubber spatulas: Heat-resistant, for scraping containers
• Measuring cups: Dedicated to soap making, for organizing ingredients
• Old towels: For insulating molds, cleaning spills
• Vinegar: Neutralizes lye spills on surfaces (not skin - use water)
• Paper towels: For wiping equipment, covering surfaces

Chapter 4: Setting Up Your Workspace

Your workspace significantly impacts your soap making experience. Whether you have a dedicated room or share your kitchen, proper setup ensures safety and success. Here are three approaches for different situations.

Option 1: Kitchen Setup (Minimal Space)

Perfect for beginners and occasional makers. The kitchen provides running water, ventilation, and existing work surfaces.

Preparation

• Clear counters completely - you need more space than you think
• Cover surfaces with plastic sheeting or thick layers of newspaper
• Ensure good ventilation - open windows, run exhaust fan
• Remove or cover any food items
• Keep pets and children out of the area
• Have cool running water accessible

Workflow

Arrange your workspace in order of use: scale and ingredients on left, mixing area center, molds on right. Keep safety gear within arm's reach. Position your lye-mixing container in the sink to contain any spills.

Cleanup

Allow raw soap residue in containers to saponify overnight before washing - it essentially becomes soap and rinses away easily. Neutralize any lye spills on surfaces with vinegar, then wash with water.

Option 2: Garage/Workshop Setup

Ideal for regular makers or those wanting separation from food areas. Provides more space and easier cleanup.

Requirements

• Sturdy table at comfortable working height
• Access to water (even a 5-gallon jug with spigot works)
• Ventilation (open door, fans, or both)
• Protection from extreme temperatures (lye reaction is affected by ambient temp)
• Good lighting
• Power outlet for stick blender

Advantages

Dedicated space means equipment can stay set up. No concerns about food contamination. Easier to manage larger batches. Spills are less critical on concrete floors.

Option 3: Dedicated Soap Room

For serious hobbyists or small-scale sellers. Maximum efficiency and safety.

Features

• Stainless steel or easily cleaned work surfaces
• Sink with running water
• Ventilation system (range hood or exhaust fan)
• Storage for equipment and ingredients
• Curing racks (proper air circulation)
• Temperature control for consistent results

Chapter 5: Safety Guidelines

Understanding Lye Hazards

Skin Contact

Lye causes chemical burns by breaking down proteins and fats in skin tissue. Diluted lye solution feels slippery (it's saponifying your skin oils). Concentrated lye or lye crystals cause immediate pain and damage. Burns may not be immediately apparent but worsen over time.

Eye Contact

This is the most serious risk. Lye can cause permanent blindness. Always wear safety goggles - not glasses, but goggles that seal around your eyes. This is non-negotiable.

Inhalation

When lye dissolves in water, it releases caustic fumes. These irritate the respiratory system. Always mix lye in a well-ventilated area, keep your face away from the container, and avoid breathing directly over the mixture.

Essential Safety Practices

Before You Begin

• Read the entire recipe before starting
• Gather all ingredients and equipment
• Put on safety gear: goggles, gloves, long sleeves, closed shoes
• Ensure ventilation is adequate
• Clear the workspace of unnecessary items
• Know where running water is located
• Keep children and pets away from the work area

Working with Lye

• Always add lye TO water, never water to lye (causes violent boiling/spattering)
• Use cold or room temperature water (not hot)
• Add lye slowly, stirring continuously
• Mix in sink or on protected surface
• Stand back and turn your face away as you stir
• Allow solution to cool in a safe location where it won't be disturbed

During Soap Making

• Keep safety gear on until all raw soap is in molds
• Wipe drips immediately
• Don't leave lye solution or raw soap unattended
• If skin feels slippery or tingly, wash immediately
• Keep vinegar nearby for counter spills (not for skin)

Emergency Procedures

Skin Contact

Immediately flush with large amounts of cool running water for at least 15 minutes. Do not use vinegar on skin - the neutralization reaction generates heat. Remove contaminated clothing while flushing. Seek medical attention for burns larger than your palm or on sensitive areas.

Eye Contact

Immediately flush with cool water for at least 20 minutes, holding eyelids open. Call emergency services. Continue flushing until help arrives. Time is critical - permanent damage can occur within seconds.

Ingestion

Do not induce vomiting. Call poison control immediately. Rinse mouth with water if conscious. Seek emergency medical care.

Chapter 6: The Basic Process

Cold process soap making follows the same fundamental steps regardless of recipe. Master this process, and you can make any soap. The following overview prepares you for the detailed recipes that follow.

Overview of Steps

Step 1: Prepare Your Workspace

Gather all equipment and ingredients. Cover work surfaces. Put on safety gear. Measure out all ingredients before beginning. Having everything ready prevents scrambling mid-process when you're working with caustic materials.

Step 2: Prepare the Lye Solution

Measure cold or room-temperature water into a heat-safe container. Slowly add measured lye while stirring. The solution will heat rapidly (up to 200F/93C) and release fumes. Continue stirring until lye is completely dissolved - the solution will be clear. Set aside to cool in a safe location.

Step 3: Prepare the Oils

Weigh solid fats (coconut oil, lard, butters) into your soap pot and melt gently over low heat. Once melted, add liquid oils. The goal is a uniform oil mixture at roughly 100-120F (38-49C).

Step 4: Combine and Mix

When both lye solution and oils are at appropriate temperatures (typically 100-120F, though many recipes work across a wide range), slowly pour lye solution into oils while stirring. Use stick blender in short bursts alternating with stirring to bring the mixture to "trace."

What is Trace?

Trace is the point where saponification has begun and the mixture has thickened enough that drizzles leave a visible trail on the surface. Light trace resembles thin custard - drizzles sink in slowly. Medium trace resembles pudding - drizzles sit on surface. Heavy trace is thick like mayonnaise.

For most recipes, you'll pour at light to medium trace. This gives you time to add extras (fragrance, color) and pour smoothly into molds.

Step 5: Add Extras (Optional)

At light trace, blend in fragrance oils, essential oils, colorants, or additives like oatmeal or honey. Work quickly - some additives accelerate trace dramatically.

Step 6: Pour into Molds

Pour soap into prepared molds. Tap molds gently on counter to release air bubbles. Smooth the top with a spatula. For standard recipes, cover molds with cardboard or a towel to retain heat.

Step 7: Insulate and Wait

Most soaps benefit from insulation during initial saponification. Cover with towels and leave undisturbed for 24-48 hours. The soap will heat up (gel phase) and then cool. After 24-48 hours, soap should be firm enough to unmold.

Step 8: Unmold and Cut

Turn out soap from molds. If using a loaf mold, cut into bars with a sharp knife or soap cutter. Cuts should be clean - if soap is crumbly, wait another day.

Step 9: Cure

Place bars on a rack with good airflow in a cool, dry location. Cure for 4-6 weeks minimum. During curing, excess water evaporates, soap hardens, and the final pH mellows. Cured soap lasts longer and performs better than fresh soap.

Chapter 7: Recipe One - Classic Castile

Castile soap is the gentlest of all soaps, made primarily or entirely from olive oil. Traditional Castile uses 100% olive oil and has been made in the Mediterranean region for over 1,000 years. It produces a creamy, mild lather suitable for the most sensitive skin.

About This Recipe

This recipe uses 100% olive oil with a 5% superfat. Pure Castile soap has some characteristics beginners should understand:

• Slow trace: May take 30+ minutes of mixing
• Long cure time: Best after 6-12 months (usable at 6 weeks)
• Soft bar initially: Hardens significantly with extended curing
• Creamy lather: Low, dense lather rather than fluffy bubbles
• Extremely gentle: Suitable for sensitive skin, babies, and facial use

Ingredients

This produces approximately 5-6 bars depending on your mold size.

Detailed Instructions

Preparation

1. Put on all safety gear: goggles, gloves, long sleeves, closed shoes.
2. Cover your workspace with plastic or newspaper.
3. Weigh all ingredients precisely using a digital scale.
4. Prepare your mold - if using a silicone mold, no preparation needed. If using a wooden mold, line with parchment paper or freezer paper (shiny side up).
5. Set out all equipment: mixing containers, stick blender, thermometer, spatulas.

Make the Lye Solution

6. Weigh 127.30g of cold distilled water into a heat-resistant container (in the sink).
7. Weigh 63.65g of sodium hydroxide into a separate small container.
8. Slowly add the lye to the water (never water to lye), stirring continuously.
9. The solution will heat to approximately 200F (93C) and release fumes. Keep your face turned away.
10. Continue stirring until all lye crystals are completely dissolved. The solution should be clear.
11. Set aside in a safe location to cool. It should reach approximately 100-120F (38-49C), which typically takes 30-60 minutes.

Prepare the Oils

12. Weigh 500g of olive oil into your main soap-making container.
13. Olive oil is liquid at room temperature, so no heating is required unless your room is cold.
14. If needed, warm gently to approximately 100-110F (38-43C).

Combine and Mix

15. When lye solution and oil are both around 100-120F, slowly pour the lye solution into the oils while stirring gently.
16. Continue stirring by hand for 2-3 minutes to ensure initial mixing.
17. Begin using the stick blender in short bursts (3-5 seconds on, 5 seconds stirring) to avoid burning out the motor and to control trace.
18. Pure olive oil soap traces slowly. Be patient - it may take 20-40 minutes of alternating stick blending and hand stirring.
19. Watch for "trace" - when drizzles from the blender leave a visible trail on the surface for a moment before sinking back in. This is light trace.

Pour and Mold

20. Once at light trace, pour the soap batter into your prepared mold.
21. Tap the mold gently on the counter to release air bubbles.
22. Smooth the top with a spatula.
23. Cover the mold with cardboard or a cutting board.
24. Wrap with towels to insulate.

Unmold and Cure

25. Leave covered and undisturbed for 48-72 hours. Castile often needs longer than other soaps.
26. Unmold when firm enough to handle without denting. If still too soft, wait another day.
27. Cut into bars if using a loaf mold.
28. Place bars on a curing rack with good airflow.
29. Cure for minimum 6 weeks, though 6-12 months produces a superior bar.

Expected Results

Your finished Castile soap will be a cream to pale yellow color with a mild, pleasant scent. Fresh bars will be soft - this is normal. With curing, they become remarkably hard and produce a unique creamy lather prized for sensitive skin care.

Chapter 8: Recipe Two - Homesteader's Lard Soap

For thousands of years, lard (rendered pig fat) was the primary soap-making fat in Europe and America. It produces a gentle, conditioning bar with creamy lather. This recipe adds coconut oil for hardness and bubbles, plus olive oil for extra mildness - a balanced, all-purpose soap.

About This Recipe

This traditional formulation offers several advantages:

• Economical: Lard is inexpensive, especially if rendered from your own animals
• Balanced: Good lather, hardness, and conditioning in one bar
• Quick trace: Much faster than pure Castile
• Reliable: A forgiving recipe excellent for beginners
• Four-week cure: Ready to use relatively quickly

Ingredients

This produces approximately 8-10 bars depending on your mold size.

Detailed Instructions

Preparation

1. Put on all safety gear: goggles, gloves, long sleeves, closed shoes.
2. Cover your workspace with plastic or newspaper.
3. Weigh all ingredients precisely using a digital scale.
4. Prepare your mold. This larger recipe works well in a loaf mold.
5. Set out all equipment.

Make the Lye Solution

6. Weigh 196.28g of cold distilled water into a heat-resistant container.
7. Weigh 98.14g of sodium hydroxide.
8. In a well-ventilated area (or outdoors), slowly add lye to water while stirring.
9. Stir until completely dissolved and clear.
10. Set aside to cool to approximately 100-120F (38-49C).

Prepare the Oils

11. Weigh the lard (350g) and coconut oil (210g) into your soap pot.
12. Heat gently over low heat until completely melted.
13. Remove from heat and add the olive oil (140g).
14. Stir to combine and allow to cool to approximately 100-120F (38-49C).

Combine and Mix

15. When lye solution and oils are both at approximately 100-120F, slowly pour the lye solution into the oils while stirring.
16. Stir by hand for 1-2 minutes.
17. Use stick blender in short bursts alternating with stirring.
18. This recipe traces relatively quickly - often within 3-5 minutes of stick blending.
19. Watch for light to medium trace (trails remain visible on surface).

Add Fragrance (Optional)

20. At light trace, add essential oils if desired (approximately 1 oz / 28g for this batch).
21. Lavender, tea tree, peppermint, or rosemary all work well with lard soap.
22. Blend briefly to incorporate.

Pour and Mold

23. Pour soap batter into prepared mold.
24. Tap to release air bubbles and smooth the top.
25. Cover with cardboard and insulate with towels.

Unmold and Cure

26. Leave undisturbed for 24-48 hours.
27. Unmold when firm. This recipe unmolds earlier than Castile.
28. Cut into bars.
29. Cure for minimum 4 weeks.

Expected Results

Your finished lard soap will be a creamy white bar with a firm texture. It produces abundant creamy lather with a luxurious feel. The coconut oil contributes cleansing power and bubbles, while the lard and olive oil provide mildness and conditioning. This is an excellent everyday soap for the whole family.

Chapter 9: Recipe Three - Luxury Shea Butter Bar

This premium recipe showcases shea butter's remarkable skin-conditioning properties, balanced with coconut for lather and olive for mildness. The result is a hard, long-lasting bar that feels indulgent and performs beautifully.

About This Recipe

Shea butter brings unique benefits to soap:

• Rich in vitamins A and E
• Exceptional moisturizing properties
• Creates a creamy, stable lather
• Naturally conditioning without being greasy
• Slight natural fragrance (can be masked or enhanced)

This formula uses a higher 8% superfat to maximize the conditioning benefits of the shea butter.

Ingredients

This produces approximately 7-8 bars depending on your mold size.

Optional Additions

This luxury recipe pairs beautifully with:

• Essential oils: Lavender, geranium, ylang-ylang, or rose
• Clays: White kaolin for silkiness, rose clay for color
• Botanicals: Dried lavender buds on top, calendula petals
• Silk: Dissolved tussah silk fibers for extra luxurious lather

Detailed Instructions

Preparation

1. Put on all safety gear.
2. Cover and prepare your workspace.
3. Weigh all ingredients precisely.
4. Prepare your mold.

Make the Lye Solution

5. Weigh 152.38g of cold distilled water into a heat-resistant container.
6. Weigh 76.19g of sodium hydroxide.
7. Slowly add lye to water while stirring in a well-ventilated area.
8. Stir until completely dissolved.
9. Set aside to cool to approximately 100-120F.

Prepare the Oils

10. Weigh shea butter (240g) and coconut oil (180g) into your soap pot.
11. Heat gently over low heat. Shea butter melts slowly - be patient.
12. Stir frequently to ensure even melting.
13. Once fully melted, remove from heat and add olive oil (180g).
14. Stir to combine and allow to cool to approximately 100-120F.

Combine and Mix

15. When both lye solution and oils are at approximately 100-120F, slowly pour lye solution into oils while stirring.
16. Stir by hand for 1-2 minutes.
17. Use stick blender in short bursts, alternating with stirring.
18. This recipe typically reaches trace in 5-8 minutes.
19. Watch for light trace.

Add Fragrance and Extras (Optional)

20. At light trace, add essential oils if desired (approximately 0.8 oz / 24g for this batch).
21. Add clay if using (1 tablespoon dispersed in a little oil).
22. Blend briefly to incorporate.

Pour and Mold

23. Pour soap batter into prepared mold.
24. Tap to release bubbles and smooth top.
25. If adding botanicals on top, sprinkle now and press gently.
26. Cover with cardboard and insulate with towels.

Unmold and Cure

27. Leave undisturbed for 24-48 hours.
28. Unmold when firm.
29. Cut into bars.
30. Cure for minimum 4-6 weeks.

Expected Results

Your finished luxury shea butter soap will be a creamy off-white bar (or tinted if you added clay). It produces rich, creamy lather and leaves skin feeling deeply moisturized. The higher superfat means some unsaponified shea butter remains in the bar, providing extra conditioning benefits. This makes an excellent facial bar or gift soap.

Chapter 10: Troubleshooting

Even experienced soap makers encounter problems occasionally. Understanding what went wrong and how to prevent it is part of the learning process. Here are the most common issues and their solutions.

Tracing Issues

Won't Trace (after extended mixing)

• Cause: Too cool temperatures, inaccurate measurements, or slow-tracing oils (like pure olive)
• Solution: Verify temperatures are at least 100F. Check measurements against recipe. For slow-tracing recipes, be patient or try the "heat and hold" method - gently warming to 140F
• Prevention: Use room-temperature or slightly warmed ingredients. Consider adding a small amount of faster-tracing oil like coconut

Traces Too Fast (seizes)

• Cause: Too hot temperatures, high percentage of fast-tracing oils, problematic fragrance oils
• Solution: Work quickly. If still pourable, get it into molds immediately. If seized solid, you may need to rebatch (grate and remelt)
• Prevention: Work at lower temperatures. Test new fragrance oils in small batches. Avoid stick blending after adding fragrance

Appearance Issues

Soda Ash (white powdery coating)

• Cause: Reaction between soap and carbon dioxide in air during saponification
• Solution: Purely cosmetic - wash or scrape off. Doesn't affect soap quality
• Prevention: Cover molds tightly, gel the soap (insulate to encourage heating), or spray tops with 91% isopropyl alcohol

Glycerin Rivers (translucent streaks)

• Cause: Temperature fluctuations during saponification, often with titanium dioxide colorant
• Solution: Purely cosmetic - soap is fine to use
• Prevention: Keep temperatures steady, avoid overheating, reduce titanium dioxide

Partial Gel (dark center, lighter edges)

• Cause: Center reached gel temperature but edges didn't
• Solution: Cosmetic only - soap is safe. Creates an interesting look some prefer
• Prevention: Insulate molds well, or don't insulate at all (no-gel method)

Texture Issues

Soft Soap (won't unmold)

• Cause: Too much liquid oil in recipe, not enough cure time, too much water
• Solution: Wait longer before unmolding. May need extended cure time
• Prevention: Balance hard and soft oils. Use water discount. Allow adequate cure time

Crumbly Soap

• Cause: Too much lye, unmolded too early, too little liquid oils
• Solution: If lye-heavy, soap may be unusable. If just unmolded too soon, let cure longer
• Prevention: Double-check lye calculations. Wait full 24-48 hours before unmolding

Oily Pockets or Separation

• Cause: False trace, insufficient mixing, temperatures too different when combining
• Solution: May need to rebatch. Small spots may incorporate during cure
• Prevention: Ensure true trace (not just emulsion). Mix thoroughly. Match temperatures

Safety Concerns

Zap Test

To test if soap is safe: Touch your tongue to the bar briefly. A "zap" like touching a battery means lye remains and soap is not safe. Properly made soap just tastes like soap (unpleasant but no zap). Test after the cure period.

If Soap Zaps

• Cause: Too much lye in recipe, insufficient mixing, false trace
• Solution: Do not use. Can sometimes be rebatched with additional oils
• Prevention: Verify calculations, ensure proper mixing, achieve true trace

Chapter 11: Curing and Storage

Proper curing transforms good soap into great soap. This final step is often rushed by eager new soap makers, but patience rewards you with a harder, milder, longer-lasting bar.

Why Cure?

Several important processes occur during curing:

• Water evaporation: Excess water leaves the bar, hardening it
• Saponification completion: The reaction continues, converting any remaining lye
• Crystal formation: Soap molecules arrange into more stable structures
• pH mellowing: The bar becomes gentler on skin
• Enhanced performance: Lather improves, bar lasts longer

Curing Guidelines

Setup

• Use a rack or shelf allowing airflow on all sides of bars
• Choose a cool, dry location away from direct sunlight
• Maintain consistent temperature and humidity if possible
• Avoid areas with strong odors (soap absorbs scents)

Timeline

• Most soaps: 4-6 weeks minimum
• High-olive/Castile: 6-12 months for best results
• High-coconut soaps: May be ready in 3-4 weeks
• All soaps: Continue to improve over time

Process

• Turn bars every few days for the first two weeks
• After initial cure, turning is less critical
• Bars should feel firm and dry to touch
• Weight loss of 15-25% indicates proper water evaporation

Storage

Before Use

• Store cured soap in cardboard boxes or paper bags - not plastic
• Soap needs to breathe; plastic traps moisture
• Label with date and recipe for your records
• Most properly stored soap improves for years

In Use

• Keep on a well-drained soap dish between uses
• Allow to dry completely between uses for longest life
• Don't let sit in water
• Consider cutting bars in half - use one while other stays dry

Signs of Quality

Well-cured soap should be:

• Firm and hard to the touch
• No longer tacky or soft
• Uniform in color (some variation is normal)
• Free from strong lye odor
• Lathers easily when wet
• Passes the zap test

Appendix: SAP Values Reference

This reference table provides saponification values for common soap-making oils and fats. Use these values with a lye calculator to formulate your own recipes.

Using This Table

To calculate lye needed for a recipe:

1. Multiply each oil's weight (in grams) by its SAP value
2. Sum all results to get total lye needed
3. Multiply by (1 - superfat percentage) for final lye amount
4. Multiply final lye by water ratio (typically 2) for water amount

Or use the free Lye Calculator at naturesplace.ca for instant calculations.