Choose a UV-cure adhesive when at least one substrate transmits light to the bond line, the lamp can reach the joint, and a water-clear bond matters. The cure happens on demand in seconds under suitable light. For glass and clear plastics the Krystal range suits these jobs. Plan a secondary cure for any shadowed area, and confirm each grade on its TDS.
Cure time and refractive index from the Krystal 1000 / 2000 / 3000 TDS. Shadowed areas need a planned secondary cure; confirm support per grade.
When is a UV-cure adhesive the right choice?
UV-cure adhesives are single part and stay liquid until you expose them to suitable light, then they cure on demand. Under a suitable lamp the cure happens in roughly 10 to 15 seconds (per TDS), so you control exactly when the bond sets. That makes them well suited to glass bonding, display and craft assembly, and any clear joint where appearance matters.
The defining requirement is light at the bond line. Because the adhesive only cures where light reaches it, at least one of the two substrates usually has to transmit light, such as glass or a clear plastic. The cured bond is water-clear, which is why these adhesives are common where the joint is visible. The MightyLoc UV-cure range is Krystal 1000, Krystal 2000 and Krystal 3000; treat per-grade differences as see each grade’s TDS in the TDS library.
| Property | UV-cure (Krystal range) | Cyanoacrylate | Two-part reactive (structural acrylic / epoxy) |
|---|---|---|---|
| Cure trigger | Suitable light at the bond line | Trace surface moisture | Mixing the two parts |
| Cure speed | On demand, seconds under the lamp | Fast, seconds | Minutes to overnight, varies by grade |
| Optical clarity | Water-clear, made for visible joints | Clear, though whitening can show near a visible joint as a class | Varies; many are not optically clear |
| Cures shadowed areas | No, needs a secondary cure path | Yes, no light needed | Yes, cures throughout the joint |
| Substrate light transmission | At least one part must transmit light | Not required | Not required |
| Best use | Glass and clear plastic, visible joints, display assembly | Fast fixturing of small parts and repairs | Load-bearing or opaque joints, gap filling |
What are the decisive selection factors?
Most UV-cure selection decisions come down to whether light can do its job, and what happens in the parts of the joint the light cannot reach. Work through these factors before you pick a grade.
- Light transmission: at least one substrate must let light pass to the bond line. Glass and many clear plastics qualify; two opaque parts do not.
- Bond-line access for the lamp: the lamp has to see the joint. A deeply recessed or fully enclosed bond line is hard to cure directly.
- Optical clarity: UV-cure bonds are water-clear, so they suit visible joints. Refractive index can matter when bonding glass for appearance; Krystal 2000 has a refractive index of about 1.48 (per TDS).
- Shadowed areas: any region the light cannot reach needs a secondary cure path, so confirm the grade’s secondary cure behaviour on its TDS before you design the joint.
- On-demand cure: the adhesive stays liquid until exposed, giving open working time, then sets in seconds. This is an advantage for precise placement and high throughput.
How does UV-cure compare with other clear and glass options?
For clear and glass bonding the usual alternatives are cyanoacrylate and two-part reactive adhesives such as structural acrylic or epoxy. Each cures differently and behaves differently at a visible joint. The table below positions the classes qualitatively. It does not give numbers, because the right values depend on the exact grade and should be read from its TDS.
Cyanoacrylate sets in seconds by reacting with trace surface moisture and needs no light, but as a class it can show whitening near a visible joint and is rigid and brittle. Two-part reactive adhesives give high strength, as a class, and cure throughout the joint without light, which suits opaque or shadowed assemblies, but they need mixing and a longer working window. UV-cure trades the light requirement for clean, on-demand, water-clear bonding.
How do you handle shadowed areas and clarity over time?
Direct line of sight from the lamp to the bond line is the simplest case. Where part of the joint sits in shadow, behind an opaque rim or a thick section, that area will not cure from the lamp alone, so plan a secondary cure path and confirm what each grade supports on its TDS.
Optical performance is a design factor as well as a cosmetic one. The bond is water-clear, and refractive index can affect how a glass joint looks; Krystal 2000 is listed at about 1.48 (per TDS). Long-term clarity behaviour varies by grade, so do not assume a single answer across the range. Read the specific grade’s TDS in the TDS library, and store product within its shelf life of about one year (per TDS).
How to choose
- If at least one substrate is glass or clear plastic and the joint is visible, a UV-cure adhesive from the Krystal range is a strong starting point because the bond is water-clear and cures on demand.
- If both parts are opaque, or the bond line is fully enclosed so no lamp can reach it, choose a chemistry that does not need light, such as a two-part reactive adhesive.
- If you need a fast tack on small parts and clarity is not critical, cyanoacrylate sets in seconds without a lamp, though as a class it can show whitening near a visible joint.
- If part of the joint sits in shadow, plan a secondary cure path and confirm the grade supports it on its TDS before committing the design.
- Match the grade to the look you need, including refractive index for glass, then verify cure light, clarity over time and shelf life against the specific grade’s TDS in the TDS library.
Frequently asked questions
Generally no. UV-cure adhesives only cure where suitable light reaches the bond line, so at least one substrate usually has to transmit light, such as glass or clear plastic. If both parts are opaque, choose a chemistry that does not need light, such as a two-part reactive adhesive. Confirm the requirement on the grade's TDS.
Under a suitable lamp the cure happens on demand in roughly 10 to 15 seconds (per TDS). The adhesive stays liquid until you expose it, so you get open working time for precise placement and then a fast set. Actual cure time depends on the lamp, the grade and the joint, so confirm against the current TDS.
Any shadowed area, behind an opaque rim or in a deep section, will not cure from the lamp alone. Plan a secondary cure path for those regions and confirm what each grade supports on its TDS. Designing the joint so the lamp can see most of the bond line keeps this simpler.
Yes, UV-cure bonds are water-clear, which is why they suit visible glass and clear plastic joints. For glass, refractive index can affect appearance; [Krystal 2000](/products/krystal-2000/) is listed at about 1.48 (per TDS). Long-term clarity varies by grade, so read the specific grade's TDS rather than assuming one answer across the range.
Shelf life is about one year (per TDS), and it holds best stored within the conditions the TDS specifies. Because the product is light-cured, keep it shielded from stray light during storage and handling. Always confirm the shelf life and storage conditions on the current TDS for the grade you hold.