Novolac Epoxy Resin

What Is Novolac Epoxy Resin?

Types of Novolac Epoxy Systems

• Standard novolac epoxy: the workhorse for hot acid and solvent duty, used as the binder in coatings, mortars and selective laminates.
• Cresol novolac epoxy: uprated again on temperature and chemical resistance, with a higher Tg and better hot-aqueous performance.
• Bisphenol-novolac hybrid: blends novolac functionality with bisphenol backbone, offering some of the chemical resistance with slightly improved toughness.
• Anhydride-cured novolac: used for the most demanding high-temperature service, with continuous duty above 150°C and excellent chemical resistance.
• Filled novolac mortars: heavily filled trowel-grade systems for acid-resistant flooring, hot oil bunds and chemically aggressive process areas.
• Hand lay-up novolac: used selectively as the binder in FRP/GRP work where vinyl ester’s chemistry is not enough, including some hot acid and hot solvent laminates.

Novolac Epoxy Key Features

Novolac Epoxy Applications

• Chemical Processing: hot acid bunds, solvent storage compounds, reactor surrounds and process drainage carrying mixed and aggressive chemistry.
• Nuclear Facilities: active drainage trenches, mixed-waste sumps and hot acid duties in fuel cycle and effluent treatment plant.
• Oil, Gas and Petrochemical: refinery process bunds, hot oil compounds and aromatic-rich service where standard epoxy would soften.
• Power Generation and Transmission: hot lube oil systems on turbine skids, ester fluid containment under modern transformers and ion exchange regeneration plant.
• Sewage and Waste Water Treatment: anaerobic digester internals, hot ferric chloride dosing zones and concentrated reagent bunds.
• Food & Beverage: hot edible oil refining, vegetable oil tank bunds and high-temperature CIP areas where rigid epoxy would soften under repeated thermal load.
• Agriculture & Aquaculture: AD digester internals, hot wash-down areas and bunded chemical stores carrying concentrated agricultural inputs.

Novolac Epoxy Chemical Resistance Profile

Novolac epoxy resists well:

• Concentrated mineral acids at elevated temperatures, where standard epoxy would soften
• Polar and aprotic solvents — DCM, DMF, MEK, acetone — at concentrations that destroy standard epoxy
• Hydrocarbons including aromatic-rich streams
• Hot water, steam and pressurised aqueous media in continuous service
• Most oxidising chemistry, including hypochlorites and peroxides
• Salts, brines and aqueous chemistry across temperature

Novolac epoxy has limitations against:

• Strong alkalis at concentration — like standard epoxy and vinyl ester, novolac is acid-side chemistry
• Hydrofluoric acid, which requires carbon-filled vinyl ester or specialist alternatives
• Heavy mechanical movement, where the dense cross-link network's brittleness becomes a liability
• UV exposure, where novolac chalks in the same way as standard epoxy

Novolac Epoxy Build Up Methods

Novolac Epoxy Surface Preparation Requirements

• Air temperature: typically 15–30°C, with most novolac systems narrowing the working envelope compared to standard epoxy.
• Substrate temperature: at least 3°C above dew point, monitored continuously across the working day.
• Relative humidity: usually below 80% RH, with novolac sensitive to surface moisture during cure.
• Substrate moisture: under 4% by weight, verified by hygrometer or calcium chloride testing.
• Pot life: typically shorter than standard epoxy, often 20–40 minutes once mixed, with strict batch control essential.
• Recoat window: system-specific and often tighter than standard epoxy, with missed windows requiring mechanical keying.
• Cure time: chemical cure is slower than standard epoxy in lower temperatures, with full chemistry not achieved until 7–14 days at standard ambient.
• Application equipment: brush, roller, airless spray and trowel, depending on the build-up. Hand lay-up uses the same tools as vinyl ester laminate work.
• Mixing discipline: exact ratios, mechanical mixing, side-and-bottom scraping. Novolac is unforgiving of partial mixing.

Novolac Epoxy Advantages and Limitations

Advantages

• The broadest chemical resistance of any chemistry in our range, covering acids, solvents, oxidisers and elevated-temperature aqueous service in a single specification
• High service temperature ceiling — 100–150°C continuous, higher in dry duty
• Outstanding solvent resistance, including DCM, DMF, MEK and acetone at concentration
• Hard, dense, low-permeability network with measurably lower water absorption than standard epoxy
• Compatible with the wider epoxy specification range, simplifying primer, mortar and topcoat selection
• Long service life — typically 20+ years on aggressive chemical duty when properly applied
• Available across multi-coat coatings, trowel mortars and selected laminate work

Limitations

• More brittle than standard epoxy, with limited tolerance for substrate movement and mechanical impact
• Higher cost per litre than standard epoxy and most polyurethane systems, justified by chemical performance rather than headline rate
• Shorter pot life and tighter recoat windows, demanding stricter batch control
• Limited resistance to strong alkalis at concentration
• UV exposure causes chalking like other epoxies; aliphatic polyurethane topcoats specified for external duty
• Requires experienced applicators and disciplined mixing, with less margin for error than standard epoxy
• Not the right choice where chemistry and temperature sit comfortably within the standard epoxy envelope

How Novolac Epoxy Compares to Other Systems

• Epoxy Resins VS Novolac: novolac is the uprated cousin: same family, denser cross-link network, much higher temperature and chemical resistance. Use standard epoxy for general duty, novolac for hot, concentrated or solvent-heavy service.
• Polyurethane Resins VS Novolac: novolac is rigid and chemistry-led; PU is flexible and movement-led. They solve different problems and are rarely interchangeable, though they are sometimes paired (PU body coat with novolac topcoat) on demanding duty.
• Versus Polyurea Resins VS Novolac: novolac wins on chemistry, temperature and acid bund duty; polyurea wins on rapid cure, mechanical toughness and waterproofing. Where chemistry and speed conflict, the duty determines which side of the trade-off matters.
• Versus Vinyl Ester Resins VS Novolac: both are premium chemical-resistance chemistries. Vinyl ester is the acid specialist with strong glass-fibre bonding for FRP/GRP work; novolac is the hot-service and solvent specialist with a broader chemical envelope. We choose between them on the specific chemistry, temperature and whether reinforcement is needed.

Novolac Epoxy FAQs