If I Modify My Wax Blend to Improve Adhesion, Do I Need to Repeat Wick and Fragrance Testing?

Yes for the wick, partly for the fragrance — scaled to the size of the change

The candle that now spots less is, strictly, a new candle. The melt pool, the way fragrance is released from it, the cure, the surface and the way the wax holds oil are all commonly described as properties of the wax mixture. Change the mixture and those results belong to the old candle, not the new one. What does not change is everything that belongs to the oil alone: its smell character, its documents, its price and the fact that you chose it. So the honest answer is not "retest everything" and not "nothing changed but the adhesion"; it is a sorted list, and the sorting depends on how big the change was.

The worked example is a maker whose container candle is a blend of Luxury Soy Wax CSI 464 and Premium Coconut Soy Wax CSI 468, previously 90:10 by weight of the wax portion. To improve adhesion in CSI's Clear Glass Jar with Golden Lid (150 gram) they moved to 70:30. At 8% in a 150 g candle, the wax portion is 138 g: the old blend was 124.2 g of CSI 464 and 13.8 g of CSI 468; the new one is 96.6 g and 41.4 g. They sell four fragrances — Lavender, Jasmine, Cinnamon Vanilla, Blue Ocean — all at 8%. That is a 20-point move of the partner wax, and it sits in tier 2 of the example house rule below.

The single cheapest step is the one most makers skip: write down, before pouring anything, exactly what changed and by how much. A ratio, a lot, a supplier, a pour temperature. The change record decides the size of the retest, and without it you will either repeat more than you need or, worse, less. The blend-ladder post covers choosing the blend; this page starts once you have chosen it.

Size the change first: three example tiers

There is no industry rule for how big a blend change has to be before a test repeats; the tiers below are an example house rule, labelled as such, that you can adopt or move. The logic is that a small shift between the same two waxes is likely to move results a little, so a short side-by-side check against the old blend (CONFIRM) is enough for most lines; a large shift may move them a lot, so the lines most sensitive to the wax repeat in full; and a new wax in the mix is a new wax.

Two things push a change up a tier whatever its size: an oil that has been difficult before — one that needed a different wick, sweated at your load or gave weak throw — and a jar family you have not tested the blend in. Whether shape belongs in qualification covers the second. The tiers are about the wax; the hardest oil and the hardest jar are where any tier's checks should start.

The retest matrix

KEEP means the result stays valid; CONFIRM means a short side-by-side check against the old blend — three candles each, one oil, a few burn cycles — and the result stands if the new blend is no worse; REPEAT means the full original test, run again; NEW means a test you never needed before. The vocabulary is the same one used across CSI's change-control guidance, so your records stay comparable.

Read the fragrance rows carefully, because "fragrance testing" means two different things. Choosing the fragrance — does it smell right, does it suit the brand, are its documents in order — depends only on the oil and stays KEEP in every tier. Testing the fragrance in the wax — does it release well at 8%, does the candle sweat, does the throw hold at your cure checkpoint — depends on the wax and re-opens. You do not have to re-choose your four fragrances. You do have to show that each still performs in the new blend.

The minimum tier-2 plan, candle by candle

For each oil, pour 3 candles in the new blend and 3 in the old blend on the same day, from the same oil bottle, with the same wick, cleaning, pour method and rack. Photograph all of them for adhesion first, then burn them in your standard protocol. For the hardest oil — here Cinnamon Vanilla, flagged by the maker's own records as the one that needed the most wick work before — add a wick ladder in the new blend: your current wick and two neighbouring wicks from your range, 3 candles each. CSI publishes no wick size for the 150 g jar, so the neighbours are yours to choose; the kit prices Eco Thick C2 and Cotton Braided 10-packs only as examples.

The plan is designed so that adhesion — the reason for the change — is proven on the same candles before they are burned, and every other line is a comparison with the old blend made the same day. That is the cheapest way to separate "the blend changed this" from "this week was different".

The release sheet

One line per oil. Every CONFIRM is judged as "new no worse than old" on your written rules; every REPEAT is judged against the original acceptance rule for that test. No industry figure exists for any of these lines — the rules are your house standard.

If one oil fails its throw CONFIRM in the new blend, you have three honest options: move that oil to a load or wick REPEAT inside the published ceilings — CSI 464 states 10%, so a blend that is mostly CSI 464 has little headroom above 8% if you treat each parent's ceiling as a cautious limit; keep that oil in the old blend as a separate formula; or accept that this blend does not suit it. Changing one fragrance's load rather than the whole collection's wax is the neighbouring decision.

The priced tier-2 retest kit

Priced from listed in-stock CSI packs with a 5% pour-loss allowance. Oils are bought in 15 g, 50 g and 100 g sizes; you will usually hold them already, so strike them off. Both waxes are listed for the old and new blends together; skip them if you hold production bags. The Clear 150 g jar comes in packs of 10 and 20 at the same per-jar price; the pack of 20 is in limited stock.

A tier-1 change — CONFIRMs on the lead oil (Lavender) and the hardest oil only, three new and three old candles each, no wick ladder — would need 12 candles and about ₹4,545.24 in CSI materials on the same basis. A tier-3 change costs more than either, because every line repeats for every oil. The size of the change is the biggest lever on what the retest costs, which is one more reason to blend in small steps.

What the new blend costs per candle

Material cost barely moves between blends of these two waxes. At the 5 kg rates — CSI 464 ₹507.40/kg and CSI 468 ₹637.00/kg — the old 90:10 candle with Lavender at the 1 kg rate, an example Eco Thin C1 wick and the jar at ₹94.40 costs ₹234.76 in CSI materials; the new 70:30 costs ₹238.34, ₹3.58 more. The real cost of a blend change is the retest, not the wax — which is why sizing the change matters more than shaving the blend's material price.

The decision rule

If the whole exercise feels heavy, that is useful information too: it is the cost of changing a formula after launch, and it is the reason a fair wax comparison and choosing a wax on every criterion together are worth doing before a range goes into production.

The CSI products in this retest

Frequently asked questions