Boro Color Brands Explained: Northstar, Glass Alchemy, TAG, Molten Aura, and More

Short answer: Colored borosilicate comes from a handful of specialist makers, and the brand on the rod changes how you should work it. Northstar Glassworks (the Borocolour line) tells you to run most of its palette neutral-to-oxidizing and treats reduction as the exception; Glass Alchemy teaches a neutral flame as its default and explains striking through crystal growth; Trautman Art Glass (TAG) is the name most associated with striking and silver-saturated colors; Molten Aura Labs melts what it calls “sandcrafted” color in three tone families; and small-batch makers like Boro Batch run limited-batch specialty colors. All of it is COE 33 borosilicate — the differences are chemistry, flame guidance, and format, and the maker’s own color notes always beat any general rule.

If flame chemistry itself is new to you, read neutral, oxidizing, and reducing flames explained first — this article assumes you can set and recognize all three.

Why the color maker matters as much as the color

Clear boro is a commodity by comparison (see the clear boro quality guide); colored boro is closer to a craft chemical. Each manufacturer develops its own formulations, and the same nominal hue from two makers can want different flame chemistry, different heat histories, and different kiln treatment. That’s why every serious color house publishes per-color working notes — Northstar’s quick guide and Glass Alchemy’s blog series are the canonical examples — and why “how do I work this color?” is always answered per color, per maker, not per hue.

One definition before the brand tour: silver glass is colored boro whose look comes from silver in the melt — colors that shift, haze, mirror, or develop metallic luster depending on flame chemistry and heat history. Every major maker sells silver-bearing colors, but the terminology differs by brand (Northstar has silver-saturated Exotics-type colors, TAG built its reputation on silver strikes, Glass Alchemy sells silver colors of its own). The behavior is covered in striking and silver glass basics.

Northstar Glassworks: Borocolour, the oxidizing-first house

Northstar Glassworks makes the Borocolour line, one of the longest-established colored-boro palettes and often the first brand a new boro worker buys. Two things define the Northstar experience for a buyer:

• Documentation. Northstar’s quick guide gives per-color working notes across the line, and its flame settings page is one of the clearest manufacturer statements on flame chemistry anywhere.
• The oxidizing-first default. Northstar’s guidance is that most of its colors should be worked in a neutral-to-oxidizing flame, because unwanted reduction damages much of the palette — muddying transparents and hazing surfaces. Reduction is treated as a deliberate, separate technique for the colors designed for it, which get their own reduction page.

Northstar also sells silver-saturated striking colors alongside its stable opaques and transparents, so a single Northstar order can span the easiest and hardest-to-work glass you own.

Glass Alchemy: numbered chemistry, neutral flames, and Crayons

Portland’s Glass Alchemy approaches color like a chemistry company. Its catalog runs on a numbering system — explained in its own blog post — that encodes color family and formulation, so related colors group together by number rather than by fanciful name alone.

Its flame guidance starts from a different default than Northstar’s: Glass Alchemy’s tutorial on setting a neutral flame teaches the neutral flame as the baseline for working its color, and the company explains striking behavior in terms of crystal growth — the size of the colorant crystals that form as the glass cycles through heat determines the color you end up with, which is why timing and temperature matter as much as flame chemistry.

Glass Alchemy is also known for its Crayon line: dense, opaque, cadmium-based brights. Two buyer’s notes there. First, the Crayons were discontinued at one point and later brought back, so check current availability rather than assuming any specific color is in stock. Second, cadmium colors (like silver colors) reward good ventilation and punish overheating — keep fumes out of your breathing zone, and see boro color troubleshooting for what boiling and burning a color looks like.

Trautman Art Glass (TAG): the silver-strike specialist

Trautman Art Glass is the brand most identified with striking and silver-saturated boro — colors that develop through heat cycles and flame chemistry rather than coming out of the flame finished. TAG presents itself as a pioneer of the colored-boro industry (that’s the company’s own framing, from taglass.com — we’ll leave the history debates to the manufacturers), and its catalog leans hard into the strike-and-reduce families that made its name.

Practical buyer facts from TAG’s site: the online store carries a $60 order minimum and offers free shipping on orders over $300 (US; verify current terms before ordering), and TAG lists glass in quality tiers — first-quality rod alongside other grades — so read the listing tier before you compare prices across brands. If striking colors are what draws you to TAG, read striking and silver glass basics before your first rod, because these are the least beginner-proof colors in boro.

Molten Aura Labs: sandcrafted color in three tone families

Molten Aura Labs is a newer maker whose pitch is what it calls “sandcrafted” glass — its term for melting color from raw materials rather than remelting other makers’ glass, which is Molten Aura’s own characterization of its process and its competitors’ (source). The company organizes its palette into three tone families, giving the line a designed, coordinated feel rather than a grab-bag of one-off colors. One terminology note: Molten Aura writes its expansion spec as 33CTE — the same COE 33 borosilicate family as everyone else here, just written in the coefficient-of-thermal-expansion style.

Boro Batch and other small-batch makers

Beyond the big houses, small independent makers like Boro Batch (borobatch.com) melt limited-run specialty colors. The appeal is distinctive colors you can’t get elsewhere; the trade-offs are availability — runs sell out and may not repeat — and thinner documentation than Northstar’s or Glass Alchemy’s. Treat small-batch colors as “buy it when you see it,” test a rod before committing it to an important piece, and don’t assume a favorite will be remelted.

The flame-setting conflict: oxidizing-first vs neutral-first

Here’s the genuinely confusing part for buyers, and it isn’t an error on anyone’s part: the two biggest documentation-forward makers give different default flame advice.

• Northstar says most of its colors want a neutral-to-oxidizing flame, and warns that accidental reduction damages much of its palette (flame settings).
• Glass Alchemy teaches the neutral flame as its working default and frames striking around crystal size and heat history (neutral flame tutorial).

These are brand-specific defaults for each maker’s own chemistry, not competing claims about physics — and both makers override their own default with per-color notes. The working rule: follow the manufacturer of the rod in your hand, then follow that maker’s color-specific note over their general default. For the full explanation of what each flame actually does to colorants, see flame chemistry: neutral, oxidizing, and reducing.

The same per-color rule applies to kilns: kiln-strike schedules are color-specific, not brand-wide. A published schedule like 1100 °F for 15–20 minutes belongs to the one color it was written for — never generalize it across a maker’s line.

Formats and pricing basics

Colored boro is sold by weight, not by rod count, in a few standard formats:

On price: expect steep variation by colorant, not by brand alone. Silver- and cadmium-saturated colors cost multiples of basic transparents because the raw materials do. The only numbers worth anchoring on are the format examples above and TAG’s ordering terms ($60 minimum, free shipping over $300) — everything else moves, so verify current pricing at the manufacturer before budgeting a palette.

Editor’s note: formats, minimums, and the price examples above are drawn from manufacturer sites as of mid-2026 and change frequently — treat them as illustrations, not quotes, and confirm with the maker before ordering.

Building a starter palette without wasting money

A sensible first color order ignores the spectacular stuff and buys forgiveness:

1. Start with stable colors — basic transparents and reliable opaques from a documentation-strong maker (Northstar’s quick guide or Glass Alchemy’s numbered families make it easy to know what you’re getting). These tolerate sloppy flame chemistry while your hands learn.
2. Buy small. Half-pound increments and sample packs exist so you can test before you commit. A starter palette of four to six colors teaches you more than one of everything.
3. Add one striking color deliberately — a well-documented silver or striking color from TAG or Northstar — as a learning project, not a production color. Read striking and silver glass basics first.
4. Save the exotic and small-batch colors for when you can diagnose your own failures — the boro color troubleshooting guide covers what goes wrong and why.
5. Match the brand’s flame default to your habits. If your torch tends to run rich, Northstar’s oxidation-sensitive palette will punish you faster than a stable-color order would.

Torches that give you real flame-chemistry control

Every brand’s guidance assumes you can actually set the flame it asks for. Any decent surface-mix or premix bench burner can run neutral, oxidizing, and reducing flames, but torches with finer mixing control make it easier to hold a precise chemistry while you work — GTT’s triple-mix burners like the GTT Lynx and GTT Cheetah are the usual examples (see GTT triple-mix technology). If you’re still choosing a boro burner, start with the best torch for borosilicate roundup — color work is exactly where flame control pays for itself.

Key takeaways

• The brand on the rod changes how you work it. Northstar defaults neutral-to-oxidizing; Glass Alchemy defaults neutral and explains striking via crystal growth; both are overridden by their own per-color notes.
• TAG is the silver-strike specialist ($60 online minimum, free shipping over $300 — verify); Molten Aura melts “sandcrafted” color in three tone families (33CTE = COE 33); Boro Batch and other small makers run limited batches that sell out.
• Formats: rod (commonly 1/2-lb increments), frit, powder, and sample packs; prices vary steeply by colorant — silver and cadmium colors cost multiples of basic transparents.
• Kiln-strike schedules are per-color, never brand-wide, and availability churns (Crayons were discontinued and revived) — check the maker’s current listing and notes every time.
• Starter palette: stable transparents and opaques first, small quantities, one striking color as a learning project, exotics later.

Related guides

• Flame chemistry: neutral, oxidizing, and reducing flames
• Striking and silver glass basics
• Boro color troubleshooting
• Clear boro quality guide

Sources

• Northstar Glassworks, “Quick Guide” — https://northstarglass.com/quick-guide/
• Northstar Glassworks, “Flame Settings” — https://northstarglass.com/flame-settings/
• Northstar Glassworks, “Reduction” — https://northstarglass.com/reduction/
• Glass Alchemy, “Setting a Neutral Flame” — https://glassalchemy.com/blogs/the-formula/glass-blowing-tutorial-setting-a-neutral-flame
• Glass Alchemy, “The Glass Alchemy Numbering System” — https://glassalchemy.com/blogs/the-formula/the-glass-alchemy-numbering-system
• Trautman Art Glass — https://www.taglass.com/
• Molten Aura Labs, “Glass” — https://moltenaura.glass/glass/
• Boro Batch, “About” — https://borobatch.com/about/

Editor’s note: brand characterizations (“pioneer,” “sandcrafted,” process claims about competitors) are the manufacturers’ own marketing statements, attributed as such. Color availability, formats, and prices change frequently — verify everything at the manufacturer before buying, and always follow the maker’s per-color working notes over any general guidance here.