Short answer: Modern dichroic art glass carries an extremely thin optical coating that reflects some colors and transmits others. The coating and the glass underneath are separate manufacturing decisions. For lampworking, identify both, choose a substrate compatible with your project, and plan where the coated surface will end up. Encasement can protect a design and change its appearance, but there is no universal coating, flame setting or burn-off temperature that applies to everything sold as dichro.
The Rainbow 1 sheet above shows why the material is compelling before it reaches a torch. The surface carries an organized range of colors. A cut strip selects part of that range; a clear cap changes how it is seen; reshaping changes the angles presented to the light. The finished pendant begins with decisions already made in a coating chamber.
What dichroic coating actually is
CBS describes its process as vacuum deposition: an electron beam vaporizes quartz and metal oxides inside a chamber, and that material condenses onto the glass. Successive layers build an optical coating. The maker reports as many as 30 layers, with a total thickness of approximately 35 millionths of an inch. These are CBS’s descriptions of its coatings, not specifications for every manufacturer’s dichroic material. CBS: what is dichroic glass.
The layers act together as an interference filter. Their thickness controls the colors that return toward a viewer and those that pass through. A painter changes a mixture of pigments; the coating manufacturer controls the layer structure. CBS says its different colors use the same coating materials, with the optical result controlled through thickness.
That distinction explains why a surface can look metallic without being a sheet of metal trapped in the glass. It also separates modern coated dichro from a colored rod whose composition extends through its entire cross-section.
Why the sheets are round, and how patterns get there
The outline of the lead photograph is a manufacturing clue. CBS says its sheets rotate during coating to maintain uniform color, and that rounds make efficient use of the chamber. Squares are possible, but require different tooling and use less of that available area. The round sheet is a consequence of production, not a requirement of lampworking. CBS: sheet shape.
Pattern is another separate choice. CBS describes creating some patterns during deposition rather than etching them afterward. A strip cut across a patterned sheet can therefore contain both a repeating shape and changing colors around its boundaries. Cutting direction becomes a design decision: inspect the complete sheet before deciding which small section belongs in a bead. CBS: patterns.
Reflected color versus transmitted color
CBS generally lists a paired color name with transmission first and reflection second. Its example is Blue/Gold: blue seen through clear glass, gold reflected from the coated surface. On an opaque black substrate, only the reflected gold is visible, but the coating retains the same name. CBS: transmission and reflection.
| What you are examining | What it tells you |
|---|---|
| Light passing through a clear coated sheet | The transmitted appearance. |
| Light returning from the coated surface | The reflected appearance. |
| The same coating on opaque glass | The reflected appearance, with transmission blocked by the substrate. |
| A photograph from one angle | One lighting arrangement, not the complete color range. |
For design trials, compare a sample against both light and dark backgrounds, then rotate it. Keep those conditions consistent when comparing coatings. This is a useful visual check, not a measurement of the coating’s spectrum. Our glass photography guide covers the broader problem of documenting a reflective, transparent object.
From optical coatings to Coatings by Sandberg
The familiar aerospace origin needs one qualification: the word dichroic predates modern coating machinery. NASA’s account discusses the Roman Lycurgus Cup, whose unusual appearance comes from metal present in the glass, alongside the later development of deposited films. Those are different material structures. A historical two-color object is not evidence of a Roman vacuum-coating process. NASA Spinoff.
NASA describes the transfer of thin-film technology into decorative work, including crystal sculpture by Jan Lewczenko. That is a documented route from technical optics to art. It does not mean that every decorative sheet uses a spacecraft specification, or that the particular sheet on a bench provides protective optical filtering suitable for eyewear.
.jpg){kind=link}
Jerry, Nona and the artist market
CBS dates its business to 1996 and identifies founder Gerald “Jerry” Sandberg, Nona Sandberg and Howard Sandberg in its family company account. It says artists encouraged Jerry to establish a consistent supply of art-grade dichroic glass. CBS company history.
The company’s first-person history, published by the Pacific Northwest Glass Guild, places Jerry in a Newport Beach vacuum-coating laboratory in the early 1970s. It recounts a conversation with an artist collecting rejected optical mirrors and subsequent work on three colors for artists: Cyan/Red, Magenta/Green and Yellow/Blue. The same account credits Nona and Jerry with establishing CBS and dates its first production to November 1996. These details come from the company’s retrospective account. CBS history in the Guild newsletter.
Its account also describes bringing artists into the factory to learn how they fused, slumped and manipulated the material. That feedback matters: a coating useful in an optical instrument and one intended for an artist’s repeated hotworking face different practical demands.
| Part of the story | What to keep separate |
|---|---|
| Ancient two-color glass | An optical effect within a different material structure. |
| Technical thin-film coatings | The process and optical principles behind deposited layers. |
| Jerry Sandberg’s early work with artists | Activity preceding the CBS company. |
| CBS from 1996 | A named manufacturer developing products for the art market. |
This is also a two-manufacturer story in many finished pieces. One company can make the glass substrate and another apply the coating. “CBS dichroic” identifies the coating maker; it does not, by itself, identify the clear glass beneath it.
Protecting the coated side
The old instruction “cap it or burn it” is too absolute to use as a universal material rule. CBS specifically reports that artists retained its coating under severe hotworking tests, with slight residue at the edges. That is a manufacturer claim about its product, not a published universal temperature limit. CBS: hotworking claim.
A more useful question is: where should this coating sit in the finished object? An exposed surface, a layer trapped between glasses and a textured coating deliberately allowed to develop are different designs. Identify the product before applying a procedure learned with another coating.
One possible encased layout places the coating toward the base glass, leaving its original backing outward. Establish the layer order from the coating maker’s instructions for the intended construction before heating. Keep the orientation recorded with the material rather than trying to rediscover it while handling hot glass.
Finding the coated side
Keep the maker’s label and original orientation with the sheet and its offcuts. A two-color name does not identify which face you are touching: the apparent color also depends on viewing angle, background and whether light passes through the glass. Inspect both faces under reflected light before cutting; if the orientation remains uncertain, obtain the coating maker’s identification guidance rather than scratching the surface to find out.
CBS recommends scoring on the uncoated side for a cleaner break. Its separate handling guidance warns against abrasive cleaning and notes that edge grinding can chip the coating together with the glass. A coating intended for hotworking still deserves careful handling on the cold bench. CBS: cutting and scratching.
Dichro formats at the torch: rod, sheet strips, and stringer
Format describes how the material arrives, not its compatibility. CBS documents coating rods, tubing, stringers, beads and finished objects as well as sheet. A coated rod and an already encased stringer are different starting materials, even when both are sold for lampworking. CBS: custom coatings.
| Format | What to establish before use |
|---|---|
| Sheet or strip | Substrate identity, coated face and intended layer order. |
| Coated rod or tubing | Where the exposed coating sits and how the planned construction encloses or displays it. |
| Encased stringer | Identity of both glasses and confirmation that the coating is already enclosed. |
| Coated frit | Glass family and whether particles were coated individually or made by crushing sheet. |
That last distinction is real. CBS says its coated frit begins as frit rather than broken coated sheets and describes a process covering much of each particle’s surface. Crushing a sheet and coating separate particles produce different distributions of glass and coating. The name “dichro frit” should not erase that difference. CBS: coated frit.
For a pendant, the format should serve the design. A flat strip can place a defined band across a clear gather. An encased stringer can place a narrow line. An implosion construction moves decoration through the clear body. Plan the finished position of the coating first, then choose material that makes that construction manageable.
Encasing dichro so the sparkle survives
Encasement places another transparent glass layer between the coating and the outside surface. It protects an internal design from direct tool contact and creates a different optical setting from exposed dichro. The thickness, curve and clarity of the covering glass become part of the appearance.
Treat a first trial as a small construction study. Keep the coating, substrate and clear identified. Record which face went inward, how the strip was arranged, and the reheating sequence. A successful sample should tell you what to repeat, rather than merely show that something attractive happened.
Air management remains the same physical problem described in encasement without bubbles: an enclosed gap becomes an inclusion. Fit the layers deliberately and keep a path for air to leave as they meet. Examine a finished trial for gaps at the edges as well as through its center. More clear on the outside cannot retroactively remove an already trapped pocket.
There is no benefit in assigning an unverified temperature or oxygen ratio to this entire category. Follow the coating maker’s process guidance and the base-glass maker’s annealing instructions. The pendant guide provides construction context; the flame chemistry guide explains the vocabulary without making one setting a universal dichro recipe.
Why dichro burns off, crazes, or goes gray
A changed appearance is an observation. It is not yet a diagnosis. Start by comparing the heated sample with an untouched piece from the same material, under the same lighting.
| Observation | First useful distinction |
|---|---|
| Color seems absent from one view | Check transmission, reflection and angle before declaring the coating gone. |
| Residue appears at an edge | Identify the coating and process; CBS acknowledges slight edge residue in its own hotworking account. |
| A rough or broken-looking texture appears | Establish whether the product was formulated to develop texture. |
| A scratch or chipped margin is visible | Separate cold handling damage from a heating result. |
| The glass itself cracks after cooling | Investigate the glass combination and thermal history separately from the optical coating. |
Crinklized is a designed texture
CBS’s Crinklized coating is formulated to develop a pronounced rough surface during firing. Its instructions distinguish it from the smoother result of its original coating and explain that leaving it exposed accentuates the effect. It is not simply ordinary dichro sold after accidental overheating.
The product page includes a kiln-fusing temperature recommendation and explicitly excludes lampworkers and furnace workers from that particular instruction. Do not turn a kiln peak into a torch setting. This is a concrete example of why both the product name and the process matter. CBS: Crinklized.
Editor’s note: This revision replaces the earlier blanket burn-off rule with product-specific guidance. CBS’s durability statements are manufacturer claims; its published pages do not provide a universal lampworking temperature limit or gas ratio. Use the current instructions for the exact coating and base glass.
Buying COE-matched dichro (33 / 90 / 96 / 104)
For the fuller explanation and testing limits, read glass compatibility beyond COE.
A familiar expansion family is a starting filter when selecting material. It is not the entire compatibility test. Bullseye explains that viscosity and thermal expansion both affect compatibility, and that equal COE figures can accompany incompatible glasses. Appropriate testing considers how the materials behave together through the intended process. Bullseye TechNotes 3.
CBS’s Rainbow 1 order page makes the substrate choice visible: it lists glass options including Bullseye, Oceanside, Moretti, Pyrex and float glass under one coating name. Choosing the attractive color first and ignoring that second field is how the wrong material can reach the bench. CBS: Rainbow 1.
| Label encountered | What to verify |
|---|---|
| 33 or borosilicate | The actual substrate and suitability for the boro combination being made. |
| 90 or 96 | The named manufacturer’s compatibility system, not just a numerical match. |
| 104 or Moretti | The identified soft-glass substrate and guidance for the chosen base and clear. |
| Float glass | Its actual specification; do not assume it belongs to a lampworking family. |
CBS says its coating does not change the underlying glass’s COE and directs users to the glass manufacturer for firing schedules. That leaves the substrate question fully in place. It also explains why an attractive unidentified offcut is a poor starting point for a carefully planned encased piece. CBS: firing guidance.
For the history behind the Moretti label, see Moretti to Effetre. Retain the substrate identification with every remaining strip after cutting; a color name alone cannot recover it later.
Key takeaways
- Identify the coating and the glass beneath it separately.
- Compare reflected and transmitted appearances before diagnosing color loss.
- Preserve coated-side orientation through cutting and assembly.
- Use the exact product’s instructions, especially for intentionally textured coatings.
- Check compatibility as a material combination, not only as a shared COE label.
Related guides
- Encasement without bubbles
- Making glass pendants
- Implosion pendant technique
- Photographing glass art
- Moretti to Effetre: the family, factories and glass
- Glass compatibility beyond COE: testing a coated strip against its base and clear
- Frit application guide: applying coated frit and other particles on hot glass
Sources
Primary manufacturer and institutional material read October 8, 2026 UTC. The Guild article is a first-person CBS company history, attributed as such above. Product photographs remain credited to their manufacturer.
-
CBS company history and its history published by the Pacific Northwest Glass Guild.
-
CBS manufacturing: coating structure, sheet rotation and patterns.
-
CBS optics: transmission versus reflection.
-
CBS handling: cutting, scratching and hotworking claim.
-
CBS formats: custom coatings, coated frit and Natural Wavy Firestrips.
-
CBS product examples: Rainbow 1 and Crinklized.
-
NASA Spinoff, Ultra-Thin Coatings Beautify Art, 2012.
-
Daniel W. Schwoerer, Bullseye Glass, TechNotes 3: Compatibility of Glasses.
-
Chappsnet, Lycurgus Cup photograph, 2023, CC BY 4.0. Photo identity and license.
Further viewing: CBS maintains an official demonstration library. Select a demonstration for the material and process you intend to use; fusing guidance does not automatically transfer to the torch.