Description
Product Overview
Bonstone Penetrating Epoxy is a two-component, very low viscosity, exterior grade, clear crack penetrating epoxy. At 250 centipoise mixed, it wicks into the structural fissures of stone instead of sitting on the surface, which is what makes it useful for consolidating slabs and strengthening weakened joints. The Bonstone data sheet covers granite and marble. In practice, fabricators use it heavily on quartzite and marble, where fissures and soft veining need to be stabilized before the slab gets cut and handled.
It is commonly used with Bonstone scrim reinforcing mesh as an alternative to rodding countertops. The 40 minute pot life at 75°F gives the resin time to travel into deep cracks before it begins to set. Per Bonstone product literature, the system provides a 40% increase in the strength of the stone.
This is the same product long sold as Touchstone Penetrating Epoxy. Bonstone is retiring the Touchstone name and moving the full line under Bonstone. There is no formulation change.
Meets ASTM C-881, Type I, II; Class C, Grade 1.
Key Product Details
| Property | Value |
|---|---|
| Chemistry | Two-component epoxy |
| Color | Clear |
| Mix Ratio | 2 parts A to 1 part B, by volume |
| Mixed Viscosity at 75°F | 250 centipoise |
| Pot Life at 75°F | 40 minutes |
| Initial Set at 75°F | 6 to 8 hours |
| Full Cure at 75°F | Within 24 hours |
| Minimum Substrate Temperature | 55°F |
| Shore D Hardness | 78 (ASTM D-2240) |
| Tensile Strength | 5,869 psi (ASTM D-638) |
| Tensile Modulus | 464,521 psi (ASTM D-638) |
| Tensile Elongation at Break | 1.5% (ASTM D-638) |
| Flexural Strength | 12,442 psi (ASTM D-790) |
| Flexural Modulus | 464,751 psi (ASTM D-790) |
| Compressive Strength | 9,204 psi (ASTM D-695) |
| Compressive Modulus | 186,455 psi (ASTM D-695) |
| Coverage | Approximately 30 sq ft per gallon at 50 mils (1/16 in). 231 cubic inches per gallon. |
| Standards | Meets ASTM C-881, Type I, II; Class C, Grade 1 |
| Shelf Life | Approximately one year in unopened cans stored dry at 75°F |
| Available Sizes | Quart Kit, Gallon Kit, Pail Kit |
Use on Quartzite and Marble
Quartzite is one of the most common uses we see for this product. Fissured quartzite and marble with soft veining often need to be stabilized before the slab can be cut, moved, and set, and a 250 centipoise resin gets into those fissures rather than bridging them at the surface. The same approach applies to marble slabs where veining runs through a cutout or a seam location.
The stone has to be completely dry, dust free, and free of oil, grease, and coatings. That last part matters on quartzite, since many slabs arrive resin treated from the quarry. Check the face before you commit to a repair, and call us if you are not sure what you are looking at.
Penetrating Epoxy vs Penetrating RS
Both products are clear, exterior grade, very low viscosity penetrating epoxies that mix 2:1 by volume. The difference is set speed and cured hardness. Standard Penetrating gives you a longer working window for deep fissures and larger slab work. Penetrating RS sets in 1 to 2 hours for faster turnaround on laminating and thin crack repair.
| Property | Penetrating Epoxy | Penetrating RS |
|---|---|---|
| Mixed Viscosity at 75°F | 250 cps | 700 cps |
| Pot Life at 75°F | 40 minutes | 12 minutes |
| Initial Set at 75°F | 6 to 8 hours | 1 to 2 hours |
| Shore D Hardness | 78 | 88 |
| Tensile Strength | 5,869 psi | 9,208 psi |
| Compressive Strength | 9,204 psi | 14,840 psi |
Performance in Production
- 250 centipoise mixed viscosity lets the epoxy wick into deep thin cracks and fissures rather than bridging them at the surface.
- 40 minute pot life at 75°F gives more working time than the rapid set version, which helps on larger slabs and deeper fissures.
- Bonstone directs mixing only the amount of epoxy that can be used within 10 minutes.
- Cure speed roughly doubles for every 10°F increase. At 85°F set time is cut in half. At 65°F it doubles. Do not apply to a substrate below 55°F, and bring all material to 55°F or above before mixing.
- Substrate must be completely dry and dust free, and free of oil, grease, and coatings.
- Do not stress the joint before the epoxy has fully cured.
- Uncured epoxy cleans from tools with toluene or xylene. Cured epoxy has to be removed mechanically.
- Can be tinted with Bonstone liquid tints when the repair needs to match the stone.
- If the material is stored below room temperature for an extended period it may crystallize into a stiff, grainy consistency. Reconstitute by heating to 150°F and stirring until it is a homogeneous liquid.
Common Applications
- Penetrating deep thin cracks in stone for high adhesive strength
- Filling fissures in granite, marble, and quartzite
- Stabilizing fissured quartzite and soft veining in marble before fabrication
- Bonding stone to stone
- Consolidating stone slabs
- Strengthening weakened joints in stone
- Reinforcing slabs and countertops when used with scrim or fiberglass mesh
- Added strength around sink and bowl cutouts
- Alternative to rodding countertops
Kit Sizes and How to Choose
| Kit | Part A | Part B | Total Mixed | Typical Fit |
|---|---|---|---|---|
| Quart Kit | 2 qt | 1 qt | 3 qt | Crack and fissure repair, occasional cutout reinforcement, shops trying the product |
| Gallon Kit | 2 gal | 1 gal | 3 gal | Regular slab reinforcement and scrim work in a production shop |
| Pail Kit | (2) 5 gal | (1) 5 gal | 15 gal | High volume shops backing full slabs on a routine basis |
All kits ship Part A and Part B in the correct 2:1 volume proportion, so you get a full ratio out of the kit without ordering components separately. Mix by volume in smaller batches as you work, only the amount that can be used within 10 minutes. Shelf life is approximately one year in unopened cans, so match the kit size to how fast the shop actually goes through it.
Special order item. Special order products cannot be canceled or returned. Call us for current lead time on your size.
Frequently Asked Questions
Can Bonstone Penetrating Epoxy be used on quartzite?
Yes, and it is one of the most common uses we see. Fissured quartzite frequently needs stabilizing before it can be cut and handled, and the low viscosity resin wicks into the fissure rather than sitting on top of it. The Bonstone data sheet specifies granite and marble, and the product is used the same way on quartzite. Confirm the slab is dry and free of any coating or quarry resin on the face before you start.
Is Bonstone Penetrating Epoxy the same as Touchstone Penetrating Epoxy?
Yes, same product. Touchstone was the brand name Bonstone Materials used on this line since 1962 and it is being retired. There is no formulation change.
Why does my Part A say Bonstone and my Part B say Touchstone?
During the brand transition, Bonstone is using up existing Touchstone label stock rather than scrapping it. You may receive a kit with one component labeled Bonstone and the other labeled Touchstone, or both cans labeled Touchstone inside a box labeled Bonstone. Either way it is the same material at the same 2:1 ratio, and nothing about the formulation changed. If a kit looks mismatched and you want it confirmed before you mix, call us at (800) 220-1966.
What is Bonstone Penetrating Epoxy used for?
It is used to penetrate and fill deep thin cracks and structural fissures in stone, bond stone to stone, and consolidate slabs. Fabricators use it on granite, marble, and quartzite, and also with scrim mesh to reinforce slabs and cutout areas as an alternative to rodding.
Which kit size should I order?
The Quart Kit (3 qt total) fits crack and fissure repair and occasional cutout reinforcement. The Gallon Kit (3 gal total) fits shops doing slab reinforcement and scrim work regularly. The Pail Kit (15 gal total) fits high volume shops backing full slabs. Shelf life is about one year unopened, so size the kit to your actual usage rate.
What is the mix ratio for Bonstone Penetrating Epoxy?
Two parts A to one part B by volume. Blend the two components thoroughly and homogeneously for a proper cure, and mix only what can be used within 10 minutes.
How long does Bonstone Penetrating Epoxy take to set?
Initial set is 6 to 8 hours at 75°F, with full cure within 24 hours. Set time is cut roughly in half at 85°F and roughly doubles at 65°F.
What is the difference between Penetrating Epoxy and Penetrating RS?
Penetrating RS is the rapid setting version. It sets in 1 to 2 hours at 75°F versus 6 to 8 hours, with a 12 minute pot life versus 40 minutes, and cures harder at Shore D 88 versus 78. Standard Penetrating is thinner at 250 cps versus 700 cps and gives more working time for deep penetration.
How much area does one gallon of Penetrating Epoxy cover?
Approximately 30 square feet per gallon when applied at 50 mils (1/16 in). One gallon is 231 cubic inches. Crack injection uses far less material than a 50 mil surface application, so coverage on repair work depends on crack depth and volume.
Why did my Penetrating Epoxy turn stiff and grainy?
Extended storage below room temperature can cause the epoxy to crystallize. Heat it to 150°F and stir until it returns to a homogeneous liquid before use.
Can Bonstone Penetrating Epoxy be tinted?
Yes. It can be tinted using Bonstone liquid tints.
Related Products
- Bonstone Penetrating Epoxy RS (Rapid Set) for faster set laminating and thin crack repair
- Bonstone Scrim Reinforcing Mesh, 3 ft x 150 ft Roll for slab and countertop reinforcement
- Bonstone liquid tints for color matching repairs
Questions on fit for a specific slab or repair, call (800) 220-1966 or email [email protected].
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