Candle Wax Formulas

Candle

What is Paraffin?

Paraffin is a common wax petroleum by-product. suitable for general candlemaking. It comes in various grades and melting points. Predominantly fully-saturated long-chain hydrocarbons.

Why does a well or cavity form around the wick?
Why does wax shrink?

Since paraffin is predominantly fully-saturated long-chain hydrocarbons, which do not chemically interatct with one another, they expand on heating as the molecules vibrate and 'writhe' with thermal energy. Conversely, as they cool and harden, this energy is lost to the surroundings and they shrink. This leads to the well or cavity that forms around the wick that must be filled to complete the candle, unless the wax is carefully formulated for reduced shrinkage.

A few words about wax additives for container candles:

Vegetable oils are high molecular weight (fatty) acids, some of which are chemically bonded to glycerol as glycerides. The fact that these oils have chemically active carbon-carbon double bonds and oxygen atoms causes them to interact with one another thru 'hydrogen bonding' and thus they are more 'bound' and tied down, unable to expand and shrink with heating and cooling. Hydrogenated vegetable oils, such as 'Crisco' shortening, have some of the double bonds saturated with hydrogen, giving rise to tristearines which are hard and waxlike. The amount of hydrogenation determines the range of hardness, soybean oil has none and is a liquid, while Crisco is partially hydrogenated and is a firmer semi-solid. Liquid vegetable oils and molten Crisco are much more viscous and syrupy than molten wax, since hydrogen bonding 'entangles' the molecules and inhibits movement and flow.

Viscous waxes (or oils) burn longer in candles than free flowing materials, like pure molten paraffin, perhaps due to slower capillary action in the wick. Beeswax requires a larger wick than paraffin since beeswax is a mixture of large fatty acids, esters, and hyrdocarbons with a fairly high relative viscosity. Vybar extends burn time by apparently artificially 'entangling' paraffin molecules as they flow toward the wick. Stearic acid seems to operate much the same way, except that whereas vyabar acts as a 'thicket' of inert tangles, stearic acid forms a tangle of molecules interacting thru hydrogen bonding and double bond chemical interactions. Vybar is a "barbed wire tangle" while stearic acid is a "thick soup."

Hot melt glues based on ethylene-vinyl-acetate seem to fall between vybar and stearic acid in their ability to harden paraffin, increase burn time, and bind oils. Hm glue is a long chain molecule like stearic acid, but with many branches or side chains like vybar. In addition, these side chains are composed of acetate groups with active oxygen atoms, available for hydrogen bonding. Thus hm glue can entangle wax and oil like both vybar and stearic acid. Where vybar fails to bind some oils like pure soybean oil at 'reasonable' concentrations, hm glue will bind and gel these oils. Hydrogenated oils like solid Crisco are bound better by vybar, leading to the observation that the 'binder' and the 'bound' make a better pair when their chemistries are similar. Crisco being more chemically inert 'likes' vybar, while soybean oils with more chemically active double bonds 'prefers hm glue.

Container Waxes

With this chemical rationale, it seems to follow that a standard paraffin wax, highly diluted by a vegetable oil, might make a suitable container wax. If the oil of choice is not fully soluble in wax, leading to 'weeping' and 'bleeding', a suitable gel agent like vybar or hm glue maybe added to bind the oil in the wax matrix.

These formulas are similar to paraffin/vaseline/vybar mixes, except that whereas vaseline is a semi-solid tangle of complex paraffin-like molecules and subject to shrinkage, vegetable oils are hydrogen bonded materials with little or no shrinkage. The oil content of the wax mix may be adjusted by changing the paraffin/oil ratio and then adjusting the overall firmness and solidity by adjusting the gel agent.

Formulas

All have very low shrinkage on cooling when poured just above the cloud point (just before the mix turns cloudy near the edges, indicating imminent gelling and hardening.

Low shrinkage wax formulas

All parts by weight, these are not percentages. All mixtures were poured unscented into 2oz glass votive holders, and burned for an hour to test for odor, soot, smoke, melt diameter, and discoloration of the melt pool, using a votive sized wick. Dye and scent tests were not performed.

  • paraffin: Chevron's Gulfwax, mp 130-135F
    the grocery store brand
  • 100% soybean oil
    store brand cooking oil
  • Crisco shortening
    name brand, not butter flavor or stick variety
  • Hot melt glue
    translucent clear sticks available from craft stores
terms:
  • firm
    softer than paraffin but harder than 'Chapstick' lip balm.
  • medium soft
    like Chapstick
  • soft
    softer than Chapstick
formulas (parts by weight):
  • Mix 1

paraffin -50

soybean oil -50

hot melt glue -10

This mix shrinks about 1/5 as much as pure paraffin, has a vanilla candle color, is translucent (not opaque) is medium soft, and has a slightly oily feel. Very slight odor when burned, less noticeable than 'liquid wax' candles.

  • Mix 2

paraffin -50

Crisco -50

vybar#103 -4

Shrinks essentially zero, is opaque white, soft, with a slight oily feel.

  • Mix 3

paraffin -50

Crisco -50

HotMelt Glue 5

Shrinks essentially zero, is opaque white, soft, with a slightly more oily feel than Mix 2.

  • Mix 4

yellow beeswax 50

Crisco 50

Shrinks zero, opaque, light beeswax color, very firm, slightly oily feel.  Might be good as an "all natural" container wax.

  • Mix 5

paraffin -50

Vaseline-50

Vybar 4

Shrinks about half that of paraffin, opaque, very firm, waxy feel (not oily).

Summary:

All these mixes seem to burn clean, without soot or objectionable odor.  The melt pool was such that a complete melt across most containers should be achievable with slight adjustment of the components and wick size.

All except Mix 5 burned without 'carbon mushrooms' forming on the wick, probably because vaseline contains polycyclic hydrocarbons known to produce carbon unless burned in an oxygen rich environment.  Mixtures 1-4 shrink less than the classic 1 part beeswax/3parts paraffin container wax.

Remember!

Variations in pouring temperature, additives, scent, color, and type of wax used will produce different results every time. Experiment to discover what you like. When trying these formulas, try small votive sizes at first and work up to large quantities.