Every shop that works white marble eventually hits the same wall. A slab of Carrara or Statuario arrives with hairline fissures running through the field, or a vein opens up under the saw, and the fill you reach for decides whether that piece ships as an A-grade top or gets argued over during a punch walk six months later. The problem is rarely the fissure. It is that most fills eventually announce themselves — a faint amber cast, a halo bleeding into the stone, or a sheen that catches morning light. On dark granite none of that shows. On white stone, all of it does.
Akemi Everclear 505 exists for exactly that problem. It is a liquid, low-viscosity, solvent-free two-component polyurethane reaction-resin system from AKEMI GmbH in Nuremberg, Germany, and the flowing grade is built to penetrate and fill fissures and pores while strengthening and finishing white and light-colored natural stone, indoors and outdoors. What follows is what the published data actually says, what each number means on a Tuesday afternoon in a working shop, and where the material rewards discipline. Every figure below comes from the manufacturer data sheet or the product listing.
What Everclear 505 Is, Chemically and Practically
Everclear 505 is a two-component polyurethane — a 2C-PUR system in the manufacturer's language — supplied as a Part A and a Part B mixed immediately before use. Cured, it is transparent. It is solvent-free and classified as no dangerous goods, which affects how it ships and how it is stored.
The flowing grade is deliberately low in viscosity, and that is the whole point. A thick knife-grade filler sits on top of a fissure and bridges it. A flowing resin runs into the void and fills it from the inside out. Those are two different repairs with two different failure modes, and confusing them is the most common selection error in this category.
The published application area is narrow and specific: filling fissures and pores, plus surface finishing and strengthening of white and light natural stone, indoors and outdoors. That last phrase carries weight. Plenty of fill resins are honest indoor products that quietly degrade in real sun, which rules them out for exterior cladding, pool surrounds, and outdoor kitchens. Everclear 505 is published as suitable for both.
The target stones are the ones where a bad fill is unforgivable: onyx, Thassos, Sivec, Carrara marble, and Statuario. These are translucent-to-crystalline light materials where a repair is visible through several millimeters of stone. The manufacturer's stated properties address that directly — excellent stability to yellowing, no bleeding in the marginal zone, and in most cases no color intensification on the treated surface.
One more property decides whether the repair reads as a repair at all. The cured product is listed as very good grindable and polishable. A resin that cures harder or softer than the surrounding stone will stand proud after honing or dish below the polished plane, and either defect catches light at a grazing angle. A fill that takes abrasives at roughly the same rate as the stone around it simply disappears.
The Published Numbers and What Each One Costs You
Mix ratio: 4:3 by weight, never by eye
The mixing ratio is 4:3, Part A to Part B, by weight. The manufacturer warns that the ratio should be maintained as closely as possible, because otherwise yellowing or color intensification may occur. The property you bought this resin for — invisibility on white stone — is the first one you lose when the mix drifts. The fix is a gram scale on the bench, a tared cup, and a ratio card taped above the station.
Weighing rather than eyeballing volume also has a technical basis. Part A has a density of about 1.07 grams per cubic centimeter; Part B is about 1.16. Close enough that guessing feels harmless, different enough that volume-based mixing walks the ratio off target across a production run. Weighing removes the variable and makes small batches repeatable.
Working time and the six-hour finishing window
The mixture can be worked for approximately 12 to 15 minutes at 68 degrees Fahrenheit. That is a short window and it should shape how the job is staged. The slab needs to be clean, dust-free, dry, positioned, masked, and lit before Part A ever meets Part B. Continuous fissures must be sealed on the reverse side first, because a through-crack drains a flowing resin straight onto the table.
After approximately six hours the material can be ground and polished. Six hours is an awkward interval in a one-shift shop — too long to wait out, short enough that an end-of-day fill is ready at first light. Shops running this material regularly build the schedule around it. Pushing abrasives onto resin that has not finished hardening smears the repair and ruins the pads.
For larger fissures or more absorbent areas, the published instruction is to apply several times rather than flooding the void in one heavy pass. That is a meaningful detail on porous or heavily fissured material, where a single pass will sink and leave a depression that only becomes obvious after the first honing step.
Viscosity, UV performance, and temperature limits
Part A runs roughly 1,600 mPa·s and Part B roughly 900 mPa·s. Those figures are what let the product flow into fissures instead of sitting on them, and they are also why preparation matters: a low-viscosity resin finds every available path, including ones you did not intend. The UV figure is the headline — 1000 hours of Q-UV with no change, tested to ISO 4892-3:2013, cycle 1. That is a defined laboratory protocol, not a marketing adjective.
On the cold end, the product must not be used below 32 degrees Fahrenheit because it will not sufficiently harden. On the warm end, preheating the stone to a maximum of 140 degrees Fahrenheit slightly shortens working and curing time but increases penetration. Both are useful levers. An unheated shop in January is a genuine failure risk; controlled preheating is a legitimate way to drive resin deeper into a tight fissure.
| Published Specification | Value |
|---|---|
| Chemical basis | Two-component polyurethane (2C-PUR), solvent-free, transparent |
| Mixing ratio | 4 : 3 (Part A : Part B) by weight |
| Working time | Approx. 12–15 minutes at 68°F |
| Grindable and polishable | After approx. 6 hours |
| Viscosity | Part A approx. 1,600 mPa·s; Part B approx. 900 mPa·s |
| Density | Part A approx. 1.07; Part B approx. 1.16 g per cubic centimeter |
| UV resistance | 1000 h Q-UV: no change (ISO 4892-3:2013, cycle 1) |
| Minimum application temperature | 32°F — will not sufficiently harden below |
| Coloring | Up to 2% AKEMI polyester coloring pastes or concentrates |
| Storage | At least 12 months, dry and cool at 41–77°F, sealed original container |
Read together, those specifications describe a material with a narrow but well-defined operating envelope. It is not a forgiving general-purpose adhesive and was never meant to be. It is a precision fill resin for light stone, and the same specifications that make it excellent at that job make it a poor choice for a cold garage in February or a mix eyeballed out of two cups.
Spotlight:
The most common failure with Everclear 505 has nothing to do with the resin and everything to do with water. The manufacturer states the product is very sensitive to water and moisture during hardening: high residual moisture in the stone may cause foaming, and high atmospheric humidity or steam may cause bubbles to form in the product. A slab that came off a wet saw two hours ago is not dry. Give it real drying time and keep shop humidity down, and most foaming complaints disappear.
Moisture, Color Matching, and Fine-Crack Technique
Treat moisture as the primary variable
The instruction is unambiguous: surfaces must be clean, free of dust, and completely dry, and atmospheric humidity should be kept as low as possible. Polyurethane chemistry reacts with water, and in a fill resin that reaction shows up as gas — foam inside the fissure or fine bubbles at the surface. Neither polishes out, because the void is inside the repair rather than on top of it.
Practically, that means sequencing. Wet-cut and wet-profile first, then let the piece dry thoroughly before filling, rather than interleaving the two. In humid seasons, shops that fill early after a wet night often get worse results than shops filling mid-afternoon with doors closed and dehumidification running. A moisture meter is cheap insurance on a high-value slab.
Coloring and sample areas
Coloring is possible by adding up to 2 percent of AKEMI polyester coloring pastes, coloring concentrates, or Spectrum pastes. Two percent is the published ceiling and worth respecting — loading a resin past its intended pigment level changes how it cures and how it takes a polish. On most white-stone work the goal is a near-invisible clear fill, with a trace of tint only where a repair crosses a distinctly gray or gold vein.
Even though the manufacturer states that as a rule no color intensification occurs, the same data sheet still recommends making a sample area. That recommendation exists because natural stone varies bundle to bundle and slab to slab. A five-minute test on an offcut from the same slab settles the question, and it is the cheapest quality-control step available when the alternative is a visible repair on a finished top.
Filling very fine cracks
For hairline work the manufacturer publishes a specific technique. If very fine cracks need filling, Part A may be diluted with up to 20 percent by weight of AKEMI Thinner EC before mixing with Part B. That thinned mixture can then fill fine cracks or holes using a disposable syringe and an 18-gauge disposable needle — genuinely useful for restoration work and for salvaging slabs with tight surface checking.
Two cautions belong with that technique. The 20 percent dilution applies to Part A before mixing, not to the mixed resin. And thinning changes flow behavior substantially, so the syringe method deserves a test on scrap before it touches the visible face of a finished piece. Tools should be cleaned immediately with AKEMI Universal Thinner; cured polyurethane does not leave a spatula gracefully.
Handling, Training, and Dust Control
Everclear 505 is labeled for professional use only, and the data sheet says why: component B contains diisocyanates and may cause an allergic reaction. As from August 24, 2023, adequate training is required before industrial or commercial use. That requirement comes from the European Union restriction on diisocyanates, which mandates training for industrial and professional users of mixtures above 0.1 percent by weight, with renewal every five years and records kept by the employer.
Shops in the United States are not governed by that European restriction, but the hazard is identical regardless of jurisdiction. Isocyanate sensitization is cumulative and not reversible — once a worker is sensitized, even trace exposure can trigger a response. Chemical-resistant gloves, eye protection, real ventilation rather than an open roll-up door, and a read of the current safety data sheet before first use are the baseline.
Dust deserves the same attention. Once the fill cures, grinding and polishing it means grinding the surrounding stone too, and natural stone dust carries respirable crystalline silica. The OSHA permissible exposure limit is 50 micrograms per cubic meter of air as an 8-hour time-weighted average, with an action level of 25 micrograms per cubic meter. Wet methods and local exhaust are the practical controls.
Waste handling is a small item with a real compliance angle. The data sheet specifies that for proper disposal the container must be completely emptied. Partially full cans of a two-component isocyanate product are a genuine disposal problem, which is another argument for mixing small, planned batches instead of opening more material than the job needs.
Inventory, Shelf Life, and Buying the Right Quantity
Stored dry and cool between 41 and 77 degrees Fahrenheit in its closed original container, Everclear 505 carries a published shelf life of at least 12 months from production. That is a comfortable window, not an unlimited one, and the storage conditions do real work in that sentence. A kit that spends a Phoenix summer on a high rack in an uninsulated shop is not being stored dry and cool.
The configuration sold here is the 2-liter set at roughly 1,900 grams, mixed 4:3, manufacturer part number PURE.11487. For a shop doing occasional high-value marble repairs, one set is usually the right purchase: the shelf life absorbs sporadic use, and buying deeper inventory of a 12-month product against unpredictable demand ties up money in material that may time out.
For shops running white stone continuously, the calculation flips. Fissure filling becomes scheduled work rather than an exception, consumption becomes predictable, and running out mid-job on a slab that is already cut costs far more than carrying a spare kit. The honest test is whether the shop can forecast a month of fill work with confidence. If it can, carry stock. If not, buy per job.
For the full published specification set, current pricing, and the manufacturer documentation links side by side, the listing for Akemi Everclear 505 Flowing UV Resistant Urethane Adhesive carries the complete technical table, directions for use, and safety notes in one place. Shops building a broader chemical program — knife-grade fillers, color pastes, thinners, sealers, and cleaners alongside the flowing grades — can work through the full catalog at the Dynamic Stone Tools store and match products to the stone types actually moving through the shop.
A last note on selection. Everclear 505 is a flowing grade, which makes it the right tool for penetrating fissures and pores and the wrong tool for building a bonded seam or filling a large open void where a knife-grade product belongs. Matching resin consistency to the repair is at least as important as matching brand, and a shop that stocks one flowing grade and one knife-grade product covers most of what a natural stone line will throw at it.
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