Polyester Mastics
Knife-grade and liquid polyester adhesives that set in minutes for filling, laminating and quick repairs.
- Filling and repairs
- Edge laminations
- Quick assembly
Best to buy: Feb–Apr, Sep–Oct
Read guideSee mastic vendors
Chemicals buying guideLast updated October 2026
Epoxy Resins
The structural glue of the stone industry.
- Price level
- Mid-range
- Best to buy
- Feb–Apr, Sep–Oct
- Top sources
Photo: Dzhang2680, CC BY-SA 3.0
Overview
What it is
Two-part epoxies are the structural glue of the stone industry. In factories, low-viscosity epoxy is spread or vacuum-infused into slabs to fill fissures and pores and to bond mesh backing. In workshops, knife-grade and liquid epoxies make seams, mitres, undermount sinks and structural repairs.
Epoxy is stronger, more water-resistant and lower-shrinkage than polyester, but slower to cure. Colour-matched grades exist, and UV-stabilised clear grades resist the yellowing that standard epoxies show in sunlight.
- Chemistry
- Two-part: resin and hardener at a fixed ratio
- Pot life
- About 10 to 60 minutes
- Full cure
- About 12 to 24 hours
- Strength
- High, low shrinkage, water-resistant
- Watch
- Non-stabilised grades yellow in UV
Applications
Best used for
- Slab reinforcementResin lines and vacuum impregnation.
- Seams and mitresColour-matched, strong joints.
- Undermount sinksStructural bonding and brackets.
- Outdoor and wet bondingWhere polyester would fail.
Origins
Which countries to source from
The producing countries that matter for epoxy resins, what each is known for, and a direct link to vendors there.
Italy Leading source
Stone-specialist resin makers
- Tenax
- Bellinzoni
Germany
Premium stone chemistry
- Akemi
China
Value resins for slab lines
- Fujian and Guangdong makers
India
Resins for granite processors
- Domestic makers
Timing
Best time of year to buy
Chemicals are made to order all year. Ship resins and water-based products in mild months: summer heat shortens shelf life in transit, and winter cold can freeze or crystallise them.
- Jan: slower or pricier
- Feb: best time to buy
- Mar: best time to buy
- Apr: best time to buy
- May: normal
- Jun: normal
- Jul: slower or pricier
- Aug: slower or pricier
- Sep: best time to buy
- Oct: best time to buy
- Nov: normal
- Dec: slower or pricier
Best time to buy Normal Slower or pricier
- Epoxy hardeners and water-based sealers can crystallise or freeze in unheated containers in winter.
- Summer container temperatures can exceed 50 °C, which shortens the shelf life of polyesters and catalysts.
- Most products have a 12 to 24 month shelf life: buy for your usage, not for a discount.
Import costs
Tariffs and import duties
Base duties for the main import markets, the extra US surcharge by origin, and the trade remedies to check before you quote a landed price.
HS codes
- 3907.30Epoxide resins in primary forms
- 3506.91Prepared adhesives based on polymers
Base import duty (MFN)
United States2.1% to 6.1%Prepared adhesives 2.1%; epoxy resins 6.1%.
European Union6.5%
United Kingdom6%
Importing into the US? Add the 2026 origin surcharge
Section 301 rates in force since 24 July 2026, stacked on the MFN rate above.
- Italy10% min.Section 301 (2026) tops the duty up to at least 10% in total; no surcharge if MFN is already higher.
- Germany10% min.Section 301 (2026) tops the duty up to at least 10% in total; no surcharge if MFN is already higher.
- China+12.5% & 30112.5% Section 301 (2026) plus the legacy China Section 301 duty (25% on most stone and machinery lines), on top of MFN.
- India+10%Section 301 (2026) adds 10% on top of the MFN rate.
- Many resins, solvents and sealers are dangerous goods: they need an SDS and correct IMDG packing and labels for sea freight.
- EU importers take on REACH registration duties for chemicals above 1 tonne a year; US importers must certify TSCA compliance.
- EU importers of epoxy resins from China, Taiwan, and Thailand may be subject to definitive anti-dumping duties under Regulation 2025/1505.
- India applies five-year anti-dumping duties on liquid epoxy resin imports from China, Korea, Saudi Arabia, Taiwan, and Thailand.
Rates checked October 2026. Indicative rates for planning, not a customs ruling. Duties depend on the exact tariff line, origin, trade agreements and the rules in force on the day of entry. Confirm with a licensed customs broker before you price an order.
Before you order
Buying checklist
- 1Get the technical (TDS) and safety (SDS) data sheets.
- 2Check that mix ratio and pot life suit your workflow and climate.
- 3Use UV-stable grades outdoors and on light stone.
- 4Colour-match on an offcut before the job.
- 5Store within the stated temperature range.
Price level: More expensive than polyester, and worth it wherever strength matters.
Vendor Network
Ready to source epoxy resins?
Compare verified suppliers, or post an RFQ and let them come to you with quotes.
Keep reading
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Cementitious and epoxy adhesives and grouts for fixing stone tiles and panels, chosen to the stone's sensitivity.
- Floor and wall tiles
- Large-format stone and sintered slabs
- Wet rooms and pools
Best to buy: Feb–Apr, Sep–Oct
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Impregnating Sealers
Penetrating sealers that line the pores with water- and oil-repellent molecules without forming a film.
- Kitchen worktops
- Porous floors and paving
- Façades
Best to buy: Feb–Apr, Sep–Oct
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