How we predict a candle recipe.
Every recipe in the Builder, the Library, and the verdicts runs through the same engine. Twenty-six rules check the recipe against the wax, wick, vessel, fragrance, and additive data we hold. Each rule that fires deducts from a starting score of 100. The remainder is your Starting-point Score. A prediction from datasheet maths, not a guarantee. Your wax batch, room, and vessel will move the real result by 10 to 15 points either way, so always burn-test.
What the score cannot see
- Your specific wax batch (soy is agricultural and varies seasonally).
- Room temperature, humidity, and draughts during pour and cure.
- Cure time before your test burn (vanillin-heavy oils keep maturing).
- Wick centring, vessel geometry tolerances, and lid use.
- Subjective hot throw and aesthetic finish.
Treat the score as a starting point. Log your real burns in your Maker's Log and the engine learns your wax, wicks, and room.
The five bands
- Excellent90 to 100Clears every rule, or trips at most one Note. Safe to sell.
- Good70 to 89Trips Notes or one Warning. Worth addressing, not a blocker.
- CautionBelow 70Multiple Warnings. Likely to underperform on burn or scent.
- BlockedAny recipe with a DangerAt least one Danger rule fires. The numeric score is hidden because a single Danger collapses the band on its own. Resolve the Danger before pouring or selling.
- IncompleteNo valueRecipe is missing wax, wick, or vessel. Engine cannot score yet.
Penalty weights
Every rule has a severity. Severity determines how much the score drops when the rule fires. Any Danger collapses the band to Blocked regardless of the numeric score.
| Severity | Penalty | Example |
|---|---|---|
| Note | −5 | Cosmetic or advisory. Example: a sprayed external coating may craze over many burns. |
| Warning | −15 | Performance or compliance risk. Example: wick is not rated for this wax kind. |
| Danger | Forces Blocked | Unsafe to burn or unsafe to sell. Example: pour temperature above the fragrance flash point. The numeric weight is bookkeeping only. A single Danger collapses the band regardless of any other points. |
Every rule we test
Every rule has its own source page. Open one to see the primary references that back it.
- Wick must be rated for this wax kind
- Wick size must match vessel diameter
- Vessel not rated for candle use
- Wax weight exceeds vessel capacity
- Pour temperature below wax's published range
- Pour temperature above wax's published range
- Fragrance load exceeds wax maximum
- Individual fragrance exceeds its own maximum load
- Pour temperature exceeds fragrance flash point
- Fragrance not IFRA-12 approved for candles
- Additive not formulated for this wax
- Additive dose exceeds manufacturer range
- Fragrance contains CLP allergens, disclosure required (UK/EU)
- Essential oil toxic to household pets
- Non-combustible additive must not enter the burn pool
- Zinc-cored wicks discouraged in modern recipes
- Wax not formulated for this vessel type
- Canning glass not annealed for sustained flame
- Remove rubber seals, bands and clips before burning
- Metal vessel surface gets hot
- Combustible or conductive body needs a liner
- Concrete vessels need a low pour temp
- Concrete is porous and must be sealed
- Inspect ceramic for crazing
- Weck rubber ring and clips are not heat-rated
- Hex / faceted glass concentrates thermal stress at edges
- Sprayed coating may craze under repeated burns
- Pillar moulds are not container vessels
- Heavy oil plus an undersized wick is a common tunnelling cause
Frequently asked
The score is a compatibility and safety floor, not editorial endorsement, and not legal advice. Verify every regulatory claim against the current text of the law before commercial sale.