Short answer: When silver glass “burns,” one of three different things has happened: the color was overstruck (the silver crystals grew past the color you wanted and went muddy or dull), a reduced surface luster was burned off by too much heat, or the glass was simply overheated in the wrong part of the flame. The strike that avoids all three is the one the color makers publish: work the glass hot until it clears, let it cool until the glow is gone, then reheat gently in a soft, bushy flame in short passes and stop the moment the color arrives. Use the flame chemistry the maker of your specific color asks for, since boro makers disagree, and watch the annealer, which can keep striking after you think you are done.
This builds on two guides you may want first. Striking and silver glass basics explains why silver colors change (crystal size) and the cool-then-reheat cycle. Why did my silver glass turn grey covers the reduction side. This page is about control: where to hold the piece, which flame, and how not to overshoot.
Three ways to “burn” silver glass
| What you see | What happened | Where it comes from |
|---|---|---|
| Muddy khaki, dull brown, or a flat color past the one you wanted | Overstruck: crystals grew too large, or to many different sizes | Too long or too hot a reheat, or bobbing in and out of the flame |
| A bright metallic sheen that went flat, grey, or disappeared | Reduced surface layer burned off or over-reduced | Heat applied after reducing, or reduction held too long |
| Bubbles, scars, or a dead surface on a heat-sensitive color | Plain overheating | Working in the hottest part of the flame, too early |
The first is a striking problem, the second is a reduction problem, and the third is a heat-control problem. They look alike from across the bench, which is why people fix the wrong one.
Where in the flame to strike
Striking wants gentle, even heat, and that is mostly a question of where the glass sits in the flame rather than how the valves are set.
Glass Alchemy, a boro color maker, points out that no flame is neutral from base to tip: the region closest to the torch face tends to be reducing, and the properly set middle of the flame is neutral (Glass Alchemy, setting a neutral flame). So a strike done close to the face can pick up reduction you never dialed in. Northstar Glassworks describes the strike itself as bathing the glass in a gentle, bushy flame; for its NS-124 Silver Amethyst it says to kiln strike or bathe the glass in a gentle bushy neutral flame to bring out the soft blue strike (Northstar, Silver Amethyst), and for amber/purple it describes a soft flame in which the surface barely glows, striking in short increments (Northstar, Amber/Purple family).
Put together: strike out in the softer, cooler region of a bushy flame, not down in the hot core near the face; keep the surface at a barely visible glow; and work in short passes so you can see the color arrive. Double Helix, which makes silver glass for soft glass workers, adds the one rule that prevents most muddy results: work hot, cool, reheat gently, and do not repeatedly “bob” the piece in and out of the flame (Double Helix, how does striking work). Bobbing gives you crystals of many sizes at once, and many sizes reads as mud.
Oxidizing, neutral, or reducing: follow the maker, not a rule
Makers genuinely disagree here, and the disagreement is the lesson.
- Northstar amber/purple must be worked in a sharp oxidizing flame and never a reducing one, or the color opacifies to a milky yellow, and the metallic haze of reduced silver that appears on first heating has to be scrubbed off with strong heat before you strike.
- Northstar Silver Amethyst is to be worked in a cool oxidizing flame specifically to prevent overheating and striking it early, and Northstar notes that prolonged reduction gives it a greyish blue opaque surface.
- Glass Alchemy’s Amazon Bronze is to be flame or kiln struck at 1075 F, worked neutral, and reduced only at the end for metallic effects (Glass Alchemy, Amazon Bronze).
- Double Helix silver colors for soft glass are shaped in a neutral or slightly oxidizing flame so the silver stays in oxide form, with any reduction left for the end (Double Helix, working with reduction colors, PDF).
The common thread is that reduction comes last, if at all, and that heat after reduction is what burns a luster off. Beyond that, the flame setting belongs to the specific color. TAG (Trautman Art Glass) colors are now produced and sold under Northstar Glassworks, so the current working notes for those rods live on Northstar’s site (boro color brands explained covers who makes what). Our flame chemistry guide covers how to read and set each flame.
Kiln striking: even color, on the maker’s numbers
A flame strikes only what it touches, which is how gradients happen. For even color through a whole piece, the makers point to the kiln, and they publish their own temperatures:
| Maker and color | Published kiln strike |
|---|---|
| Northstar amber/purple family | Hold un-struck, haze-free glass at 1125 to 1150 F for about sixty minutes, or until the desired intensity |
| Northstar NS-124 Silver Amethyst | Kiln strike at 1050 F |
| Glass Alchemy Amazon Bronze | Kiln strike at 1075 F |
| Double Helix (soft glass, kiln-strike colors) | Annealer set at 1000 F and left for hours, per its annealing FAQ |
These are boro figures from Northstar and Glass Alchemy and a soft-glass figure from Double Helix; never carry one across to the other family. A kiln strike above your glass’s annealing temperature still has to be followed by a proper annealing cycle, which our annealing schedules guide covers.
Editor’s note: kiln-strike temperatures and times are the makers’ published figures for the named colors and vary by color, batch, thickness, and kiln. Test with a spacer bead or a scrap piece before committing a finished work, and follow the maker’s current instructions over this table.
The annealer that keeps striking
The most frustrating overstrike happens after the torch is off. A piece struck perfectly in the flame goes into the annealer and comes out further down the color sequence. Double Helix explains why: annealing is a time and temperature relationship, and higher annealing temperatures can cause surface luster to oxidize off (burn off) on reduction colors and color shift (over-striking) on striking colors. It describes its own annealing range as broad, roughly 900 to 1000 F for its soft glass, with most small objects relieved within about 30 minutes at around 950 F (Double Helix, annealing schedule). A common community approach when the annealer keeps restriking is to fire spacer beads and bring the annealing temperature down in small steps between sessions until the silver glass stops restriking; that is shop practice, not a published schedule (the other 104 makers’ published annealing figures are in COE 104 annealing schedule). Per Double Helix’s own time and temperature point, the lower you go, the longer the soak needs to be, so do not drop the temperature without lengthening the hold.
If it went too far
For silver striking colors, overstruck is usually recoverable. Double Helix’s guidance is to take the glass back up to full working heat until the crystals dissolve and it returns to clear, then cool and strike again. On the boro side, Northstar describes its striking colors as repeatable, noting that they do not burn out the way certain soda-lime colors can (Northstar, borosilicate glass). A burned-off reduction luster is also usually a do-over: clear it in a clean flame, cool, and reduce again gently, as our grey silver guide describes. What does not recover is a surface that boiled or scarred, which is why heat-sensitive colors get the slow, cool warm-up in our boro color troubleshooting guide.
A short routine that works
- Shape at working heat, in the flame the color’s maker specifies.
- Take the color hot enough to clear, if the maker’s notes call for it.
- Move out of the flame and let the glow disappear completely.
- Reheat out in the soft, bushy part of the flame, surface barely glowing, in short passes.
- Stop at the color you want; do not bob.
- Reduce last, briefly, and keep heat off the luster afterward.
- Garage and anneal at a temperature that does not restrike, confirmed with test pieces.
Related guides
- Striking and silver glass basics
- Why did my silver glass turn grey?
- Flame chemistry: neutral, oxidizing, and reducing
- Boro color troubleshooting
- Boro color brands explained
- Glass annealing schedules and COE 104 annealing schedule
- Silver and gold fuming guide
- Dot application and placement: why reactive dot stacks go muddy
Sources
- Double Helix Glassworks, “How does striking work?”
- Double Helix Glassworks, “What annealing schedule do you suggest?”
- Double Helix Glassworks, “Working with Reduction Colors” (PDF)
- Northstar Glassworks, Amber/Purple family
- Northstar Glassworks, NS-124 Silver Amethyst
- Northstar Glassworks, Borosilicate glass (striking colors)
- Glass Alchemy, “Setting a Neutral Flame”
- Glass Alchemy, Amazon Bronze 287 (working notes)