Materials That Block a 1070nm Fiber Laser Beam
A handheld fiber laser welder operates at 1070nm — near-infrared, invisible to the eye, and not blocked by materials that work against visible light. Standard welding curtains, ordinary rubber, white fabrics, and most plastics offer little or no protection against a fiber laser beam. Understanding which materials actually absorb or reflect 1070nm energy — and which ones do not — is essential for building a safe laser welding environment.
This guide covers both flexible materials (for hand protection, joint backing, and portable barriers) and rigid materials (for permanent safety enclosures and beam stops), with notes on how each behaves at welding power levels.
The Physics: What Determines Whether a Material Blocks a Laser Beam
Two properties matter: absorptivity at 1070nm, and thermal capacity — the material's ability to handle the energy it absorbs without igniting or burning through.
Absorptivity at 1070nm is determined by the material's electronic structure. Materials with free electrons (metals) reflect or absorb strongly. Carbon absorbs across a wide spectrum including 1070nm. Many polymers, ceramics, and light-colored materials are partially or fully transparent at 1070nm — the beam passes through them as if they were glass.
Thermal capacity determines whether the absorbed energy can be dissipated safely or whether the material burns, melts, or ablates. A material can have excellent absorptivity but fail in practice because it burns through too quickly.
For laser welding applications, the relevant scenario is usually not the focused beam at the weld point (no material survives that indefinitely) but the diverged beam through a gap — which has the same total power but spread over a larger area, and the scattered or reflected beam from a joint. Both are dangerous, and both can be addressed with the right materials.
Materials That Work
Graphite Felt
Best all-around flexible absorber for welding applications.
Graphite felt is a flexible, fibrous carbon material rated for temperatures above 2000°C (carbon sublimates at 3642°C). Absorptivity at 1070nm is above 95% — nearly all incident energy is absorbed rather than reflected or transmitted. It is available in sheets from 3mm to 25mm thickness from industrial thermal suppliers and carbon fiber distributors.
In a laser welding context, graphite felt is used as:
- A backing pad behind joints to catch any beam that passes through a gap
- A portable beam stop clamped or taped behind small parts
- A surface protector on the welding table
Under a focused beam at full weld power, graphite felt will eventually ablate — it burns slowly, producing carbon dust and visible charring. This is actually useful: the charring is a visual indicator that the beam reached the felt, which means a gap existed in the joint. Treat visible charring as a signal to inspect fit-up.
Against a diverged beam through a gap, graphite felt provides sustained protection. The energy density is lower, the material handles it well, and it does not ignite under typical conditions. For hand protection behind a joint, graphite felt placed between the workpiece and the hand provides meaningful secondary protection.
Source: Industrial thermal suppliers, carbon fiber distributors, graphite machining suppliers. Available as Graphite Felt, Carbon Felt, or RVC (Reticulated Vitreous Carbon) foam in some configurations.
Carbon-Loaded Silicone Sheet
Best flexible option where elasticity and conformability matter.
Silicone rubber loaded with carbon black absorbs 1070nm energy well — the carbon black filler provides the absorptivity, the silicone provides the flexibility. Carbon-loaded silicone is softer and more conformable than graphite felt, which makes it useful for backing curved joints or irregular surfaces.
Silicone begins to degrade at approximately 250–300°C, which limits its performance under sustained direct exposure. Against a diverged beam or scattered energy at lower power density, it performs well. It is not appropriate as a primary beam stop against a direct, focused laser path.
Uses in a welding setup:
- Gasket material clamped behind curved joints
- Pad material on the welding table surface
- Secondary protection layer behind a copper backing bar
Source: Laser safety equipment suppliers, industrial rubber suppliers. Sold as "laser-absorbing silicone," "carbon-filled silicone sheet," or "NIR-absorbing elastomer."
Commercial Laser Safety Blanket and Curtain Material
The documented, rated option for formal safety programs.
Commercial laser safety blankets and curtains are manufactured specifically for fiber laser containment. Construction varies by manufacturer but typically involves:
- Woven fiberglass substrate (high temperature resistance, no melt-through behavior)
- Carbon-based absorbing layer or coating
- Reflective outer layer on some products to redirect rather than absorb energy
These products carry optical density (OD) ratings at specific wavelengths and power levels. An OD4 rating at 1070nm means the material attenuates the beam by a factor of 10,000. For a 2000W laser, OD4 material reduces transmitted power to 0.2W — below the threshold for skin injury.
Manufacturers include Kentek, Lasermet, Haas Laser Technologies, and Laser Safety Industries. Products are available as roll goods (cut to size), pre-made curtains with grommets, and welded blankets for wrapping specific equipment.
This is the appropriate choice when:
- A formal laser safety plan is required (ANSI Z136.1, OSHA 29 CFR 1910.97)
- Insurance or facility management requires documented material specifications
- The installation is permanent and needs to meet specific OD requirements
Source: Kentek Corporation, Lasermet Ltd., Laser Safety Industries, Haas Laser Technologies. Request a product rated specifically for 1070nm (fiber laser wavelength).
Copper (Rigid — Reflective, Not Absorptive)
The standard backing bar material for welding applications.
Copper does not absorb 1070nm energy — it reflects approximately 95–98% of it. This makes copper behave differently from the absorbing materials above: instead of converting the laser energy to heat within the material, it redirects the beam away from the joint.
In a welding context, this is the preferred behavior for a backing bar. The beam that passes through a gap hits the copper surface and reflects at an angle determined by the surface geometry. Because copper does not absorb the energy, it does not heat up rapidly and it does not fuse to aluminum or stainless steel workpieces — it can be reused indefinitely.
Copper backing bars are typically 6–12mm thick flat bar stock positioned directly behind the weld joint. The reflected beam exits at an angle away from the joint rather than continuing in the original beam direction. This is more predictable and controllable than absorption, where the energy is locally deposited and heats the material.
A practical detail: the reflected beam from copper is still dangerous. The reflection angle and direction should be considered when positioning the copper bar — reflected energy should not be directed toward the operator or bystanders. Positioning the bar flat and horizontal under a horizontal butt joint directs any reflected energy downward into the table surface.
Flexible copper: Copper mesh or woven copper fabric is available and can be used for backing curved joints. It is less reflective than solid copper due to gaps in the weave, but performs significantly better than nothing.
Aluminum (Rigid — Partially Reflective)
Aluminum reflects approximately 90–92% of 1070nm energy, somewhat less than copper. It can function as a backing bar material where copper is not available. Unlike copper, aluminum can fuse to the weld root on some joints — particularly stainless steel welding — and may become difficult to remove. Use copper in preference to aluminum for backing bars. Aluminum is acceptable for fixed backing fixtures where the weld does not reach the backing surface.
Tungsten Sheet (Rigid — High Absorption, High Temperature)
Tungsten melts at 3422°C and absorbs 1070nm energy at approximately 50–55% efficiency — lower than carbon, but with extreme temperature tolerance. Thin tungsten sheet (0.1–0.5mm) is used in some laser safety applications where space is limited and high temperature resistance is required. It is expensive and not commonly stocked. For most sign shop and light fabrication applications, graphite felt or copper is a more practical choice.
Materials That Do Not Work
Standard welding curtains (orange or green vinyl): Designed to block UV radiation and visible arc light. They are partially or fully transparent to 1070nm infrared. A fiber laser beam passes through them with little attenuation. Do not use as a laser safety barrier.
Standard welding gloves (leather, wool): Leather absorbs some 1070nm energy but burns rapidly at weld power levels. They provide no meaningful protection against a direct or near-direct beam. Laser-rated gloves are a separate product category.
White or light-colored fiberglass: White ceramic fiber blanket (Kaowool), white fiberglass insulation, and similar light-colored materials are largely transparent at 1070nm. They are effective against infrared radiation from hot objects (radiant heat) but not against coherent laser energy at 1070nm.
Standard rubber and neoprene (without carbon black): Transparent or semi-transparent at 1070nm depending on formulation. Standard rubber products are not reliable laser barriers.
Cardboard and paper: Combustible and offering no meaningful attenuation. Not appropriate.
Clear polycarbonate: Used for CO₂ laser enclosures (CO₂ is blocked by polycarbonate), but transparent to fiber laser at 1070nm. A polycarbonate enclosure designed for a CO₂ laser cutter offers zero protection against a fiber laser.
Practical Combinations for a Welding Setup
For most sign shop and light fabrication laser welding operations, the practical material setup is:
Behind every joint: A copper backing bar (6–12mm flat bar, positioned flush with the underside of the joint) as the primary beam stop. A piece of graphite felt behind the copper as secondary protection and as a visual gap indicator.
On the welding table surface: Carbon-loaded silicone sheet or graphite felt pad to protect the table and contain any scattered energy at the workpiece level.
Around the welding area: Commercial laser safety curtains rated OD4+ at 1070nm, hung on a simple pipe-and-hook frame to define the controlled zone. Anyone inside the zone wears OD5+ laser safety glasses for 1070nm.
On the operator's hands (if fixturing is not possible): Laser-rated gloves designed for fiber laser wavelengths, worn in addition to (not instead of) proper fixturing and backing bar practice.
For specific guidance on setting up a safe laser welding area with Ascent equipment, see our laser welder safety guide and workstation setup guide. Questions about your specific configuration can be directed to our team.
