G1.2 Gauge – Transparent crack monitor

Technical specifications

Operating principle of the G1.2 gauge

The G1.2 gauge belongs to the Saugnac G1 family of gauges. All of these products share the same principles for mounting, reading and monitoring via the Saugnac app.

What sets the G1.2 gauge apart is that it is transparent: this crack monitor blends into its substrate and is far less visible than a white G1 gauge, while offering the same measuring performance indoors and outdoors.

When to use the G1.2 gauge?

The G1.2 gauge is designed for crack monitoring on surfaces where appearance matters:

• dressed stone or exposed stone façades;
• historic monuments, churches and heritage buildings;
• high-end interiors: entrance halls, shops, function rooms, occupied homes;
• decorative renders or painted walls whose appearance must be preserved.

It measures changes in the opening of horizontal, vertical, diagonal or corner cracks, indoors and outdoors.

On a listed or historic building, the choice of instrument also depends on regulatory constraints: see our sheet on crack monitoring on historic buildings for discreet, non-invasive solutions.

Installing the G1.2 gauge

The G1.2 gauge is installed following the same guidelines as the whole G1 family. Full details are given in the mounting principle section of the G1 gauge product page, and in the sheet How to install a Saugnac G1 crack monitor?

In short, the gauge is fixed with the adhesives supplied or mechanically through its two Ø4 mm holes. On a surface that must be preserved, adhesive bonding avoids any drilling.

The sliding arm of the G1.2 gauge features a grooved fold line. This groove makes it easy to bend the sliding arm for corner mounting without any additional accessory. Installation examples (regular internal corner, irregular internal corner, crack on an external edge) are detailed in the How to measure a corner crack? section of the G1 gauge product page.

Reading and monitoring measurements

Readings are taken with a vernier to the nearest 0.1 mm. Full details are given in the reading principle section of the G1 gauge product page.

Each gauge is uniquely identified by an ID and a QR code. The G1.2 is one of the gauges that can be read automatically in the Saugnac app, provided free of charge.

The free app for monitoring and automatic reading is available at https://saugnac.app. Find full explanations on how the app works. If you prefer not to use an app, an Excel monitoring file is also available to track measurements on your sites.

Frequently asked questions about the G1.2 gauge

What is the difference between the G1 and G1.2 gauges?

Both gauges have the same 0.1 mm resolution and the same range of approx. 20 mm, and both can be used indoors and outdoors. The G1.2 gauge is transparent, so it is far less visible on the substrate. The G1 gauge comes in boxes of 10, the G1.2 in boxes of 5.

Can the G1.2 gauge be installed on a corner crack?

Yes. The sliding arm has a grooved fold line that allows corner mounting without any additional accessory. Where the corner is irregular, an aluminium angle bar or an intermediate plate can still be used.

Is the G1.2 gauge resistant to UV and weather?

Yes. Its body is made of impact-resistant calendered PVC with UV stabiliser, like the G1 gauge. It can be installed outdoors, on exposed façades. In busy areas where the gauge may be damaged, an anti-UV protective cover is available as an option.

Can the G1.2 gauge be read with a smartphone?

Yes. Each gauge carries a unique QR code, and the Saugnac app reads the vernier automatically, records the readings, corrects the measurement for temperature and generates trend graphs.

How can the gauge be fixed to stone that must not be drilled?

The double-sided self-adhesives supplied avoid any drilling, provided the surface is smooth, dry and clean. If the stone is rough, bonding can be reinforced with epoxy glue. Mechanical fixing with screws should be reserved for crumbling or persistently damp substrates.

Does the gauge need to be set to zero when installed?

No. The first reading only serves as a reference: comparing this initial reading with subsequent readings is what quantifies how the crack is changing. Ideally, position the vernier triangle between 10 and 11 when installing the gauge.