Bonstone Clarion SF Styrene-Free Vinyl Ester Seam Adhesive

Bonstone Clarion SF is a styrene-free seam adhesive built on two-part vinyl ester chemistry, made in the USA and used by countertop shops for seaming, mitering, laminating, and repair work on natural stone, quartz, and solid surface. It comes in three viscosities and it is tintable in the shop with Bonstone Liquid Tints, so you color the resin to the slab before you catalyze it and pull a seam that reads as part of the material instead of a line through it. The working window is short by design: 4 to 5 minutes of working time, tack-free in about 20 minutes, and you are back on the stone. Full walkthrough of the tint-then-catalyze sequence is further down this page.

Key Product Details

Tested Bond Strength, Clarion SF #5

Bond strength was tested by an independent laboratory using ASTM D905, the standard test method for strength properties of adhesive bonds in shear by compression loading. Pieces measuring 2″ x 1.5″ were bonded to create a 3.0 sq in. bonding area, five replicate specimens were run per substrate, and the reported values are averages of the five. These figures are for the #5 Knife Grade only and do not carry over to #1 or #9.

On granite and marble the stone split from itself before the bond let go, which is the outcome you want on a seam. On Dekton some specimens failed at the bond line, so treat sintered surfaces as a test-first substrate rather than an assumption.

Performance in Production

• The 98:2 ratio is a volume call, not a scale call. A golf ball of Part A to a pea of Part B means a two-man crew can batch it on a board without weighing anything, and the 5 minute pot life means you only mix what you can spread.
• Going over 2% BPO cream hardener to force a faster set shortens the pot life and the cure time and causes significant discoloration of the adhesive. On a tinted seam that discoloration is the whole job, so hold the ratio even when you are chasing an install.
• Gel in 2.5 to 5 minutes and tack-free in roughly 20 minutes at 70°F means the stone is workable again inside half an hour. Allow the 20 minutes before you go back to it.
• Shore D lands at 85 to 90 across all three viscosities, so grinding and polishing behavior at the seam does not change when you switch from #5 to #9 for a vertical joint.
• Temperature and humidity both move the window. Above 70°F the working time gets shorter. Lower temperatures and higher humidity extend the cure. Bring the kit and the slab to 75°F before you mix so the material behaves the way the numbers say.
• The base is very light and translucent, which is what lets a few drops of tint drive the color instead of fighting an amber baseline. Pull a sample across an offcut before you commit, because a pile on the board does not read the same as the same material compressed into a hairline joint.
• Two year shelf life in unopened containers, stored indoors at room temperature. Replace lids after every use and keep the material away from high heat and cold.
• Application conditions are interior, vertical and horizontal for #5 and #9, horizontal only for #1.

Common Applications

• Countertop seaming on natural stone and quartz
• Miter folds, waterfall edges, and mitered buildups
• Edge lamination and bullnose work
• Re-attaching broken stone
• Chip, crack, and scratch repair
• Filling and repairing on solid surface and other hard surfaces
• Structural adhesion on hard surfaces in interior work

Choosing a Viscosity

Available Sizes and Part Numbers

Every kit ships with the matching BPO cream hardener. The Pail Kit and the Super Saver Kit both contain 5 gallons of Part A. The difference is packaging: one pail, or four 1.25 gallon cans so you only open what a job needs.

Switching From Another Knife Grade Seam Adhesive

Clarion SF is an alternative to the knife grade seam adhesives most shops already run, including products from K-Bond and Superior. It is not a drop-in equivalent to any of them. Working time, hardener dosing, and tint behavior all differ product to product, so pull a test seam on an offcut of the material you are running before you put it on a job.

Two things make it worth a look. The first is that the bond data is real and it is on stone. Clarion SF #5 was tested by an independent laboratory under ASTM D905 at 1,085 psi shear on granite and 869 psi on marble, with the stone failing before the bond in both cases. Plenty of knife grade adhesives publish tensile and compressive figures measured on the hardened resin, which tells you about the plastic and not about whether it holds to your slab.

The second is the styrene. Styrene is a volatile organic compound. The International Agency for Research on Cancer classifies it as a Group 2A probable human carcinogen, and the US National Toxicology Program lists it as reasonably anticipated to be a human carcinogen. In an enclosed shop, which is where most seaming and lamination happens, it is also an indoor air quality question with workplace exposure thresholds attached to it. Bonstone cites ERA Environmental’s white paper on styrene in adhesive products as the background for the styrene-free formulation.

We are not characterizing what is in anyone else’s formula. If you want to know whether the adhesive on your shelf today contains styrene, its Safety Data Sheet will tell you.

Related Products

• Bonstone Liquid Tints, for in-shop color matching. During Bonstone’s brand transition some tint bottles still carry the Touchstone label. Same product.
• Bonstone Glacier, a UV stable urethane for exterior work, which Clarion SF is not rated for.
• Knife-grade adhesives for stone fabrication, to compare Clarion SF against the other seaming chemistries we stock.

How Tinting and Seaming a Vinyl Ester Adhesive Works

The order of operations matters more than anything else on a tinted seam. You tint the resin before you add the hardener, because once the BPO goes in you have 4 to 5 minutes total and no time to correct a color.

• 1. Prep the joint. Surfaces have to be clean and sound. Remove dirt, laitance, loose chips, and any other foreign matter, then clean and dry both faces.
• 2. Bring everything to temperature. Both components and the substrate should come to room temperature, 75°F, before you mix. Cold stone and cold resin will not behave like the data sheet.
• 3. Pull your Part A. A golf ball-size portion of resin onto the mixing board. Mix only what you can spread and bond inside the working time.
• 4. Tint before you catalyze. Add Bonstone Liquid Tints one drop at a time into the Part A portion and mix until you hit the color. Nothing else goes in yet.
• 5. Check it in a thin film. Drag a little of the tinted resin across a scrap of the material with a blade. A pile on the board looks nothing like the same material squeezed into a hairline joint, and this is where most color misses get caught.
• 6. Add the hardener. A pea-size portion of Part B into the golf ball of tinted A, then mix thoroughly for one minute. Do not exceed 2%. More hardener does not buy you a better cure, it costs you pot life and it discolors the seam.
• 7. Apply immediately. Trowel it into the joint and close the seam. Total working time is 4 to 5 minutes and it gets shorter above 70°F.
• 8. Wait, then go back to work. Tack-free in about 20 minutes at 70°F, at which point you can keep working the stone.

The process runs on natural stone, quartz, solid surface, and other hard surfaces, in interior applications. #1 Flowing is horizontal only. #5 and #9 handle both horizontal and vertical joints.

Bonstone’s Clarion SF walkthrough

Frequently Asked Questions

What is Bonstone Clarion SF used for?

Clarion SF is used for seaming, mitering, laminating, filling, and repairing natural stone, quartz, solid surface, and other hard surfaces in interior work. Shops also use it for re-attaching broken stone and for chip, crack, and scratch repair. It is troweled into the joint and tinted in the shop to match the material.

What is a styrene-free alternative to K-Bond Poly-Epoxy or VIVID?

Bonstone Clarion SF is a styrene-free two-part vinyl ester seam adhesive that fills the same role: knife grade paste for seams and miters, tintable, polishable, three viscosities. It is an alternative, not an equivalent. What sets it apart in this category is published bond testing on stone rather than on the cured resin alone. Clarion SF #5 was tested by an independent laboratory under ASTM D905 at 1,085 psi shear on granite and 869 psi on marble, with the stone failing before the bond. Many knife grade seam adhesives publish tensile and compressive figures for the hardened plastic, which tells you about the resin and not about whether it holds to your slab. If you want to know whether the product on your shelf contains styrene, its Safety Data Sheet will tell you.

What is the Clarion SF equivalent to Superior Gold GV-5?

Clarion SF #5 Knife Grade is the grade that matches GV-5 by position in the line. Both families use the same three-step numbering, so a shop switching over reads straight across: flowing is #1, knife grade is #5, and the thicker knife grade is #9. That covers format and consistency only. Clarion SF is offered as an alternative rather than a match, it is styrene-free, and it is rated for interior applications only, so if any of your work goes outdoors that job moves to a different product. Read the switching answer below before you change over.

What changes if I switch to Clarion SF from another knife grade seam adhesive?

Four things, all from Clarion SF’s own published data. The ratio is stated by volume, not by weight. Most knife grades give you a weight percentage of BPO. Clarion gives you 98 parts A to 2 parts B measured as a golf ball of resin to a pea of hardener, which is faster on a board and needs no scale, but it is a different habit if you have been weighing. The window is short. Gel is 2.5 to 5 minutes and total working time is 4 to 5 minutes, so mix smaller batches than you are used to for the first few seams. The base is very light and translucent, so it takes noticeably less pigment than a product with an amber or pearlescent base and a tint is easy to overshoot. Add color a drop at a time and check it in a thin film on an offcut. It is interior only, with no published UV stability rating, so outdoor kitchens and exterior work move to Bonstone Glacier. Pull a test seam on the material you actually run before you put it on a job.

Which Clarion SF viscosity should I use, #1, #5, or #9?

Use #5 Knife Grade for general seaming, mitering, and laminating, #9 High Viscosity when the joint is vertical or unsupported, and #1 Flowing for horizontal work where you want the adhesive to run into the joint on its own. #1 is rated horizontal only. All three cure to the same 85 to 90 Shore D and gel in the same 2.5 to 5 minutes, so switching grades does not change how the seam polishes. Most shops that stock one grade stock #5.

Is Clarion SF an epoxy or a vinyl ester?

Clarion SF is a two-part vinyl ester adhesive, not an epoxy, though the trade often files it under knife grade epoxy or poly-epoxy. Knife grade epoxy, poly epoxy, vinyl ester seam adhesive, and stone seam glue all get used for products in this role, so if you searched any of those terms you are in the right place. What matters on the floor is that it is a two-part, trowel-applied, tintable, polishable seam adhesive with a 98:2 hardener ratio.

Can I use Clarion SF on an outdoor kitchen?

No. Bonstone rates Clarion SF for interior applications only and publishes no UV stability, freeze-thaw, or high humidity rating for it. For outdoor kitchens, exterior cladding, or anything seeing sustained sun and temperature cycling, use Bonstone Glacier, a 1:1 urethane rated for interior and exterior use in both vertical and horizontal applications. Glacier’s published QUV testing ran 500 hours of alternating condensation and UV-A exposure with no change in yellow index at a delta E of 0.78, and it can be applied in below-freezing temperatures. Call us at (800) 220-1966 to talk through the install. Using an interior adhesive outdoors is one of the more common causes of a seam callback, and it is not a repair you can make without cutting the seam back out.

Does Clarion SF work on porcelain or sintered stone like Dekton?

Clarion SF #5 was tested on Dekton at 698 psi shear under ASTM D905, with some specimens failing at the bond line rather than in the stone, so treat sintered surfaces as a test-first substrate. Porcelain is not covered in the published test data. If you are bonding porcelain slab, call us at (800) 220-1966 before you commit a job to it and we will tell you what we have seen work.

What is the Clarion SF mix ratio, and what happens if I use too much hardener?

The ratio is 98 parts Part A to 2 parts BPO cream hardener, measured by volume as a golf ball-size portion of resin to a pea-size portion of hardener. Exceeding 2% shortens the pot life and the cure time and causes significant discoloration of the adhesive. On a tinted seam that discoloration undoes the color match, so resist the temptation to over-catalyze for speed.

Is Clarion SF made in the USA, and what is the shelf life?

Yes, Clarion SF is made in the USA. Shelf life is two years in unopened containers stored indoors at room temperature. Replace lids after every use and keep the material away from high heat and cold, both of which shorten it.

Questions on Fit for Your Seam?

Call (800) 220-1966 or email [email protected]. Chemical Concepts, 410 Pike Road, Huntingdon Valley, PA. Safety Data Sheets for Bonstone products are available directly from Bonstone Materials at (800) 425-2214.

K-Bond, VIVID, Poly-Epoxy, Superior, and Superior Gold are trademarks of their respective owners. Chemical Concepts is not affiliated with, endorsed by, or sponsored by those companies. Product references are for identification and comparison purposes only, and Clarion SF is not represented as equivalent to, or a replacement for, any of them.