Paraffin Slack Wax

Paraffin slack wax is the semi-refined, oil-bearing wax drawn off during petroleum dewaxing, used as a feedstock for candle blending, packaging wax, and industrial formulation. It differs from fully processed paraffin in one key way: it retains a higher oil content, which is exactly what makes it useful for blending rather than for high-clarity finished goods. This guide walks procurement and technical buyers through what slack wax is, how it is produced, and what to check before placing an order.

Who this guide is for

This article is written for three buyers who search for paraffin slack wax for different reasons. Candle manufacturers and blenders need it as a raw input for economy and utility candle lines, container candles, and grave, church, or mourning candles. Wax distributors and traders need to understand grade terminology so they can specify correctly to their own customers. Formulators in packaging and textile-yarn paraffin applications need oil-content and melting-range data before they commit to a supply contract. If you fall into any of these groups, the sections below are organized by the question you are most likely asking.

Quick facts

• Paraffin slack wax is a semi-refined petroleum wax with a comparatively high oil content, produced during the dewaxing stage of lube-oil refining.
• HTS heading 2712 groups slack wax together with petroleum jelly, paraffin wax, microcrystalline wax, and other mineral waxes under the same customs classification (U.S. International Trade Commission, 1998).
• UN Comtrade's HS code 271220 defines "paraffin wax" for trade-statistics purposes as containing less than 0.75% oil by weight (UNdata, undated) — slack wax, by contrast, is the higher-oil fraction taken before that further processing step.
• Oil content in petroleum waxes is measured by ASTM D721, and congealing point by ASTM D938 (ASTM International, 2017).
• Paraffin waxes are generally stable in storage: they are not affected by aqueous acids, alkalis, or most oxidizing and reducing agents, though they may be incompatible with strong oxidizing agents (NOAA CAMEO Chemicals, undated).

What is slack wax and how does it differ from paraffin wax?

Slack wax is the crude wax fraction separated from lubricating base oil during the dewaxing process. It carries a meaningfully higher oil content than fully processed paraffin wax, which is why it is not sold as a finished, high-clarity product on its own. Instead, it is valued precisely for that oil content: blenders use it to formulate softer, more workable wax systems for economy candles, slack-wax blending programs, and packaging wax, where a fully processed low-oil paraffin would behave differently. UN Comtrade's trade classification for paraffin wax (HS 271220) sets the boundary at less than 0.75% oil by weight (UNdata, undated) — slack wax sits above that oil-content threshold, which is the practical line buyers use to tell the two apart.

How is slack wax produced and how does the refining process work?

Slack wax is generated as an intermediate stream when lubricating base oils are dewaxed to meet cold-flow specifications. The wax crystals that would otherwise cloud or solidify the base oil are filtered or solvent-separated out, and that separated fraction — still carrying entrained oil — is slack wax. From there it can be sold as-is for blending applications, or sent through further deoiling and hydrofinishing to reduce oil content for other end uses. Because the degree of further processing varies by refinery, buyers should always confirm the specific oil-content and melting-point figures for the batch they are quoting, rather than assuming a single industry-standard value.

Why the refining step matters to a buyer

A buyer sourcing slack wax for blending wants to know how much oil is present and how consistent it is batch to batch, because oil content changes how the wax behaves in a candle pour, a coating line, or a masterbatch mix. This is a formulation input, not a cosmetic-finish product, so the relevant question is always: does the oil content and melting range suit my process, not how clear or white the wax looks.

What is the oil content and melting point range of paraffin slack wax?

BHD Group does not publish numeric oil-content or melting-point specifications for its slack wax in this article, because those figures vary by grade and batch and should be confirmed against the certificate of analysis for the specific lot being quoted. What buyers should know is which standards govern how those numbers are measured, so any figure a supplier quotes can be checked. Oil content in petroleum waxes is determined using ASTM D721, which applies to waxes with a congealing point of 30°C or higher and containing no more than 15% oil, with the congealing point itself measured by ASTM D938 (ASTM International, 2017). For slack wax used in specialty surface applications, ASTM F3418-20 sets out a differential scanning calorimetry method for measuring transition temperatures (ASTM International, 2020). Melting point can also be assessed by cooling-curve methods; the ISO cooling-curve standard for petrolatums and high-viscosity petroleum waxes notes that results can differ depending on which method is used, with related methods given in ISO 3841 and ISO 2207 (ISO, undated) — worth noting since ISO 3841:1977 itself has since been withdrawn (ISO, 1977).

Paraffin slack wax is used in which industries and for what purposes?

The confirmed application for the waxes family, which includes paraffin slack wax, is candle making, serving the candles industry. Within that industry, slack wax's higher oil content makes it a natural fit for blending into economy and utility candle lines, container candles, and grave, church, and mourning candles, where softness and burn characteristics matter more than clarity.

Candle makers and blenders

For candle producers, slack wax is typically not poured neat; it is blended with harder paraffin grades — such as HP3, M3, or UL2 — to hit a target hardness, oil retention, and burn profile. Buyers running slack-wax blending programs should ask suppliers for consistent lot-to-lot oil content, since variability there is what drives inconsistent pours downstream.

Distributors and traders

Distributors reselling slack wax into candle, packaging, or textile-yarn paraffin markets need clear grade documentation to pass on to their own customers. Because slack wax sits in the same customs heading as paraffin wax, petroleum jelly, and other mineral waxes (U.S. International Trade Commission, 1998), correct labeling at the point of sale matters for both customs clearance and downstream formulation accuracy.

What technical criteria should be considered when selecting quality paraffin slack wax?

Buyers evaluating a slack wax supplier should look past a single spec sheet and confirm how the material was tested, not just what number it reports.

What to check before you order

• Confirm the oil content figure and the method it was measured by (ASTM D721 applies to waxes with a congealing point of 30°C or higher and ≤15% oil).
• Ask for the congealing point per ASTM D938, and how it was determined.
• If melting point matters to your process, confirm which cooling-curve or DSC method was used, since results vary by method.
• Request a current certificate of analysis for the specific lot, not a generic product datasheet.
• Clarify intended end use — candle blending, packaging wax, textile-yarn paraffin — so the grade matches your process.
• Check storage compatibility: paraffin waxes are generally stable but may be incompatible with strong oxidizing agents.
• Confirm HS/customs classification for your shipment, since slack wax shares a heading with several related mineral waxes.
• Ask about origin and consistency of supply across repeat orders.

Working with BHD Group

BHD Group supplies paraffin slack wax and related wax-family products, Turkish-origin and processed to origin, through BHD Sourcing. We work from documented specifications, not adjectives — buyers who need a specific oil-content or melting-point figure should request the certificate of analysis for the lot in question. If slack-wax blending, container candles, or packaging wax are part of your production line, get in touch to discuss specification and volume.

Sources

• ASTM International (2017): D721 Standard Test Method for Oil Content of Petroleum Waxes — https://store.astm.org/d0721-17.html
• ASTM International (2017): D938 Standard Test Method for Congealing Point of Petroleum Waxes, Including Petrolatum — https://store.astm.org/d0938-12r17.html
• ASTM International (2020): Standard Test Method for Measurement of Transition Temperatures of Slack Waxes used in Equine Sports Surfaces by Differential Scanning Calorimetry (DSC) — https://store.astm.org/f3418-20.html
• ISO (1977): ISO 3841:1977 Petroleum waxes — Determination of melting point (cooling curve) — https://www.iso.org/standard/9403.html
• ISO (undated): ISO petroleum wax melting-point standard — https://www.iso.org/standard/12524.html
• United Nations Statistics Division (UNdata) (undated): UNdata — Trade of goods, US$, HS, 27 Mineral fuels, mineral oils and mineral waxes — http://data.un.org/Data.aspx?d=ComTrade&f=_l1Code%3A28%3BcmdCode%3A271220&q=Paraffin+waxes
• U.S. International Trade Commission (1998): HTS Chapter 27 (archive) — heading 2712 — https://www.usitc.gov/tata/hts/archive/9810/981c27.pdf
• NOAA CAMEO Chemicals (undated): WAXES: PARAFFIN — https://cameochemicals.noaa.gov/chemical/18025