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Hxtal epoxy adhesive is the only epoxy resin we know of that resists yellowing when exposed to light. Its exceptional stability comes from its ultra-high purity, during manufacturing, all trace metal ions are removed. In ordinary epoxy adhesives, these residual metal ions are what trigger discoloration over time. Because of this extraordinary level of purity, Hxtal must not be treated like a typical hardware store epoxy adhesive.
Mixing Hxtal Epoxy
Hxtal comes in two liquid parts, both of low viscosity. Hxtal epoxy should be weighed out accurately: one part by weight of Part B, plus three parts by weight of Part A. Transfer both parts from the original containers using glass medicine droppers into a small, clean, glass mixing jar, then mix thoroughly with a glass rod. Do not rush, there is PLENTY of time.
Using Freshly Mixed Hxtal
At this point, the Hxtal is ready to use, at least for some applications. Freshly mixed Hxtal is very thin. For many tasks, such as cementing porcelain, it may be too thin. Let it stand, lightly covered, for several hours to thicken. You will not lose bond strength by using thickened Hxtal, and it stays in the joint line far better than freshly mixed, very thin Hxtal.
However, freshly mixed Hxtal has one outstanding property: it penetrates cracks quickly, making them disappear from view. For best results, warm the crack and its surroundings to about 120°F (using a hair dryer on low or a heat lamp at two feet). Then apply one drop of freshly mixed Hxtal to the crack. If all goes well, the crack will vanish. Wipe off any excess adhesive and set the piece aside for a week.
Freshly mixed Hxtal is also ideal as a coating for ground glass surfaces. For example, an abrasive cut pattern in glass coated with Hxtal will appear etched rather than abraded.
Setting and Curing Hxtal
Hxtal sets slowly. At 75°F, it requires about seven days to achieve 90% of its ultimate bond strength. However, after 24–30 hours, Hxtal is usually set enough to hold two parts together if no stress is applied. This is the ideal time for clean-up.
Use a single-edge razor blade or razor knife to scrape off excess resin—solvents are NOT recommended, as they can migrate into the joint line and weaken the bond, sometimes much later, showing as microbubbles at the joint edge. If you wait past 24 hours, removal becomes extremely difficult.
Always check that parts are aligned correctly before leaving them. Hxtal joints are very unforgiving and extremely difficult to separate after a few days of curing.
Use Hxtal in Glass Art
Many glass artists use Hxtal epoxy to glue pieces of glass into assemblies, which are later cut, sliced, and re-glued. In these cases, we recommend pre-treating all surfaces with an A-1100 solution in reagent-grade isopropyl alcohol. This eliminates microbubbles that often form later along sawn edges.
To apply, clean the surfaces thoroughly, then wipe with A-1100 solution using a lint-free rag or brush. Let the solvent evaporate, leaving a thin film. Immediately bond with Hxtal as usual.
Thin vs. Thick Joints
Bond strength is not necessarily better with freshly mixed thin Hxtal compared to thicker Hxtal. In fact, more viscous Hxtal has advantages, especially for gluing large, heavy pieces of glass. If the adhesive is too thin, the weight of the pieces may squeeze out too much, leaving a weak joint.
Thicker Hxtal helps avoid this problem, and in extreme cases, tiny glass shims can be used. Microscope cover glass fragments make excellent shims.
Thicker joints (up to 1 mm) are often more durable. Fully cured Hxtal is tough rather than brittle, and this toughness allows thicker joints to accommodate slight expansion and contraction over time.
Caution When Speeding Hxtal Cure
Attempts to accelerate curing must be handled with extreme care. Never heat freshly mixed Hxtal with an open flame, hot plate, heat lamp, or hair dryer—this risks uneven curing, overheating, or even fire.
If you must speed up thickening, use only a water bath at 120°F. Heat for 15 minutes, then remove and stir at room temperature. Repeat in small increments if needed, but be cautious with larger batches (over 100 grams), which may exotherm dangerously. Keep cold water nearby for safety.
Curing time can also be shortened by placing the artifact in a warm 80–100°F area for a day or two. However, do not do this within the first 36 hours, as freshly mixed Hxtal may run out of the joint. After 36 hours, it is thick enough to remain stable at that temperature.
Important Note
All directions and suggestions above are for educational purposes only. Proper testing should always be conducted before applying Hxtal to valuable work.
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