Seizing and trace acceleration: causes, prevention and batch rescue

TL;DR: Acceleration trace = mass thickens within 1-3 minutes (still controllable). Seizing = immediate jamming into a stiff dough (unusable). Both situations are solved by lower temperature, light trace or hot process rescue.

Seizing and trace acceleration are two related but distinct complications in CP soapmaking. Trace acceleration is the rapid thickening of the soap mass - still manageable. Seizing is the immediate thickening of the mass to an unusable consistency similar to a hard paste or crumbly mass.

Both situations are catch-alls - either the batch can be adapted or saved by the hot process method.

What is trace acceleration and how to recognize it

Trace acceleration: thickening occurs within 1-3 minutes after the addition of the problematic ingredient. The mass is still usable, but the window for processing (especially swirly, layers, dragging) is drastically shortened.

Acceleration levels:

• Mild: Trace will speed up, but you have 2-5 minutes to pour into the molds. Suitable for single color soap.
• Medium: The mass thickens quickly, within 60-90 seconds. Spoon into moulds, do not use for design.
• Strong: The mass becomes a mass in the bowl - pouring it out is difficult. Press into the mold with your hands (with gloves).

What causes trace acceleration

Essential oils and fragrance oils:

• Eugenol - cloves (Syzygium aromaticum), cinnamon (Cinnamomum cassia, C. zeylanicum)
• Cinnamaldehyde (cinnamaldehyde)
• Vanillin - in vanilla fragrance oils
• Aldehydes (C-11, C-12)
• Styrax
• Some floral FOs (frangipani, tuberose)

Additives:

• Honey - sugars accelerate saponification
• Milk - lactose reacts with lye, increasing the temperature accelerates the trace
• Sugar (added for foaming)
• Clays - especially bentonite in higher doses
• Resin (benzoe, myrrh)

Conditions of production:

• High temperature oils or lye (above 50 °C)
• Overheated production room
• Too strong trace before adding EO/FO
• Vysoký obsah kokosového oleje nebo palmjádrového oleje (>50 %)

How to prevent trace acceleration

Lower production temperatures

Work at a temperature of 35-40 °C for both oils and leaching solution. If it is 30 °C outside, cool the room. Every extra 5 °C doubles the rate of chemical reaction (van’t Hoff's rule).

Light trace as a starting point

Do not continue blending with a blender on medium or strong trace before adding the EO/FO. Add fragrances on light trace (emulsion without visible thickening) and then pour.

Separate addition of accelerating components

If a recipe contains both honey and accelerant EOs, add them separately or consider omitting one.

Test ahead

Always test a new FO or EO in a small batch of 200-300 g of oils before using in a full batch. Record the behaviour.

What is seizing and how to recognize it

Seizing is an extreme form of acceleration - the mass goes from a thin emulsion to a solid, waxy or crumbly consistency within seconds. Mixing is impossible, pouring into moulds unfeasible.

Result: The mass looks like cottage cheese, raw dough or coarse paste. The colors are erratic, the design nonexistent.

Common causes of sepsis:

• Extreme amount of accelerating EO/FO (you add too much or too strong extract)
• Combination of multiple accelerating components at the same time
• Temperatures too high
• Rescue attempt to add FO when trace is too strong

Rescue of a jammed batch: the Hot Process (HP)

If the trace has accelerated to a state where it cannot work normally, you have one reliable rescue option: cooking with the hot process method.

HP rescue procedure:

1. Transfer the whole mass to a slow cooker / crockpot or ovenproof pot.
2. Set to a low temperature - 60-70 °C. 80 °C in the oven.
3. Stir every 15-20 minutes - the mass will first thicken further, then melt and become the consistency of mashed potatoes (applesauce stage).
4. After 45-90 minutes, perform the ZAP test: take a small piece of soap (wear gloves), gently touch with your tongue. If it burns or tingles - saponification is still in progress. Neutral = done.
5. Add EO/FO and additives (colorants) after the HP phase is complete - before pouring into the molds.
6. Fill the molds - HP soap is waxy and less liquid, does not require design.

Result of HP rescue batch: Functional soap with a rustic look. No swirls or layers. But fully functional and safe.

Moderate Acceleration Rescue (no HP)

If the mass thickened quickly, but is still pourable:

Chaotic pour: Pour the mixture into the mould as quickly as possible. The mass will not be even - it will be full of air bubbles or uneven texture. But the soap will be functional.

Spoon pack: Use a spoon or spatula to fill the mould. The texture will be rustic. Tap the mould on the table to remove air bubbles.

Rescue one color: If you were planning a multi-colored soap - forget about the design and pour one color. At least the function will be saved.

How to work safely with accelerating EOs

The smell of cinnamon: Cinnamon (bark or leaf) has an IFRA limit of 0.05-0.6% and is strongly accelerated. Two solutions:

1. Use fragrance oil with cinnamon scent - FOs are formulated for controlled acceleration.
2. Add cinnamon as a dry powder (not EO) for aroma and color without acceleration.

The smell of cloves: Similar to cinnamon - eugenol accelerates strongly. Limit to a maximum of 0.5% or combine with orange FO for a clove-orange scent with less accelerating FO.

Vanilla FO: Always test acceleration and allow for browning (see Fragrance oils). Work on light trace and pour quickly.

Diagnostic table

Frequently asked questions

What is the difference between acceleration and seizing? Acceleration = the mass thickens within 1-3 minutes but is still usable. Seizing = instant jamming, soap is unusable.

Can accelerating EO be used safely at all? Yes, if you keep the temperatures lower, test ahead and add on a light trace.

How long does HP rescue take? Approx 45-90 minutes in slow cooker or oven plus cooling. 2-3 hours total.

Will HP soap look bad? HP soap has a rustic look - without swirls and design. But it is fully functional and safe.

Can I add EO/FO after HP rescue? Yes, add after the HP phase is complete (ZAP test neutral) and just before pouring into the molds.

What temperatures are safe for work? 35-40 °C is ideal. Above 50 °C, the risk of acceleration increases significantly.

What if the HP rescue fails? In extreme cases (complete separation of the oils from the lye) the soap can be discarded. It is rare.

See also:

• Troubleshooting encyclopedia - overview of all problems
• Fragrance oils in soap - soap safe test, FO selection
• Essential Oils in Soap - overview of accelerating EOs
• What is cold process - basics of trace and saponification