Student Material 001: Glass Engraving and Finishing Reference Guide

Material ID: U12M4-MAT-001

Engraving Methods Comparison

Method	Mechanism	Depth	Texture	Equipment Cost	Skill Level	Best For
Rotary	Abrasive burr grinds surface	0.1-1.0mm	Directional, visible tool marks	Low	Medium	Custom line work, lettering, one-off pieces
Sandblast	Abrasive particle impact	0.1-5.0mm+	Even frost, non-directional	Medium	Medium	Area frosting, deep carving, production masks
Acid etch	Chemical dissolution	0.01-0.05mm	Very fine, uniform frost	Low	Low	Even surface frost, simple designs
Laser	Thermal micro-fracture	0.1-0.3mm	Fine, precise, digital	High	Low (digital)	Production, photos, precision, repeatability

Rotary Engraving Reference

Burr Selection Guide

Burr Type	Tip Shape	Size Range	Best For
Fine point	Conical, sharp	0.5-2mm	Detailed lines, lettering, fine detail
Ball nose	Spherical	2-6mm	Broad strokes, textures, graduated depth
Cylinder	Flat-bottomed	1-4mm	Channels, flat-bottomed grooves
Flame	Tapered, rounded	2-5mm	Blending, edge softening, transitions
Inverted cone	Inverted tapered	2-4mm	Undercutting, V-grooves

Speed and Pressure Guidelines

Parameter	Recommended Range	Too Low	Too High
Speed (RPM)	15,000-25,000	Burr grabs, skips	Thermal cracking, rough cuts
Pressure	Light, consistent	No engraving	Chipping, cracking
Feed rate	Slow, deliberate	Overheating one spot	Loss of control, uneven lines

Lubrication

• Apply water to glass surface before starting
• Reapply every 30-60 seconds during engraving
• Purpose: dust suppression, cooling, cleaner cuts
• Alternative: light machine oil (less mess but harder to clean)

Sandblast Engraving Reference

Media Selection

Media	Aggressiveness	Particle Size	Finish	Use
Aluminum oxide	High	80-220 grit	Deep frost, matte	Deep carving, fast material removal
Silicon carbide	Very high	80-220 grit	Sharp frost	Hardest glass, finest detail lines
Glass bead	Low	100-200 mesh	Satin, soft	Light frosting, delicate surfaces
Garnet	Medium	80-150 grit	Medium frost	General purpose

Blast Parameters

Parameter	Light Etch	Medium Carve	Deep Carve
Pressure	40-50 PSI	50-70 PSI	70-90 PSI
Distance	8-10 inches	6-8 inches	4-6 inches
Duration	15-30 sec	1-3 min	3-10 min
Media	Glass bead or fine AlOx	Medium AlOx	Coarse AlOx

Resist Film Reference

Resist Thickness	Use	Durability
3 mil (0.003")	Light surface etch, single stage	Withstands 30-60 seconds blast
5 mil (0.005")	Medium carving, multi-stage	Withstands 2-3 minutes blast
8 mil (0.008")	Deep carving	Withstands 5+ minutes blast
10+ mil (0.010")	Multi-stage deep relief carving	Withstands extended blasting

Multi-Stage Carving Process

1. Apply full resist, cut complete design
2. Remove first stage areas (deepest carving) — blast
3. Remove second stage areas — blast
4. Remove third stage areas (shallowest) — blast
5. Remove remaining resist — finished piece has 3D relief

Acid Etching Reference

Etching Cream Application Checklist

1. Don PPE: chemical-resistant gloves (neoprene/butyl rubber) + safety glasses
2. Verify calcium gluconate gel is accessible
3. Clean glass with isopropyl alcohol, dry completely
4. Apply vinyl resist, burnish edges thoroughly
5. Remove design areas from resist
6. Apply thick, even coat of etching cream with foam brush
7. Set timer: 5-10 minutes (per manufacturer)
8. Rinse thoroughly under running water
9. Remove resist, clean with alcohol
10. Dispose of all materials in hazardous waste

Troubleshooting Acid Etch Quality

Problem	Cause	Fix
Uneven frosting	Thin or uneven cream application	Apply thicker, more even coat
Blurry design edges	Cream seeped under resist	Burnish resist more thoroughly, especially edges
Spots in protected areas	Resist had gaps or bubbles	Inspect resist more carefully, press out all bubbles
Weak/light etch	Insufficient time or old cream	Increase time or replace cream
Streaky etch	Brushed cream back and forth	Apply in one smooth coat, do not agitate

Laser Engraving Reference

CO₂ Laser Parameters for Glass

Parameter	Recommended Range	Notes
Power	15-40% (of 40-60W laser)	Lower is safer; multiple passes preferred
Speed	300-600 mm/s	Higher speed reduces thermal stress
Resolution	300-600 DPI	Higher for photo/halftone work
Passes	1-3	Light passes produce better results than one heavy pass
Focus	On surface	Standard focus for surface engraving

Wet Paper Technique

1. Apply single sheet of damp newsprint or paper towel over glass surface
2. Secure edges with tape
3. Engrave through the paper
4. Paper absorbs thermal shock, producing more even etch
5. Remove paper after engraving, clean glass

Finishing Techniques Reference

Fire Polishing

Parameter	Recommendation
Flame type	Neutral to slightly oxidizing
Speed	1-3 seconds per inch of edge
Preheating	Hold piece near flame 10-15 seconds before contact
Distance	Flame tip touches or nearly touches edge
Passes	Usually 1; repeat only if insufficient

Mechanical Polishing Progression

Stage	Abrasive	Grit Equivalent	Surface Result
1	Silicon carbide	220	Rough smooth (removes 80-120 grit marks)
2	Silicon carbide	400	Fine smooth
3	Silicon carbide	600	Very fine, slight haze
4	Cerium oxide	~10,000+	Optically clear polish

Edge Finish Selection Guide

Desired Result	Method	Time per Edge	Notes
Safe to handle (satin)	Grind to 220	2-3 min	Minimum for any handled piece
Smooth matte	Grind to 400-600	5-7 min	Good for lead came assembly
Glossy/transparent	Fire polish	10-30 sec	Fastest to optical clarity
Optically clear (cold)	Cerium oxide polish	5-10 min	When fire polish is not possible
Beveled	45° grind + polish	10-15 min	Decorative, refracts light

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Last Updated: 2026-03-19