Hello, everyone.

This is Enta.

I received a question the other day regarding quality control for sprayed coating thickness, so I’d like to answer it here.

This is what the typical spray-applied thickness looks like, right?

Is there a standard for this square shape?

That’s how it used to be, but these days it’s not even included in the standard specifications, is it?

It used to be written there.

It's just the Ministry of Land, Infrastructure, Transport and Tourism, though.

Basics of Quality Control for Sprayed Coating Thickness

Number of measurements: 1 location for 200 m²; 2 locations for areas of 200 m² or less (to facilitate management of measurement points)

Testing Timing: Drill holes after spraying. (Drilling)

Inspection hole size: 10 cm × 10 cm; however, the Ministry of Land, Infrastructure, Transport and Tourism specifies 20 cm × 20 cm (though 10 cm is now also acceptable).

Measurement location: Average of the four corners

In the past, the standard specifications listed 20 cm × 20 cm, but that is no longer the case.

So I think even 10 cm × 10 cm is fine, and nobody’s going to nitpick about that anymore, lol.

As for when to drill the holes, it’s best to do it within 30 minutes to an hour after spraying, lol.

To be honest, it's really hard to bring out a hammer drill and chisel away at it after it's completely hardened.

It's easier to dig them up while they're still soft, and they're easier to care for.

Whether to fill the access hole before the inspection or leave it open until the inspection is up to the person in charge or the inspector, so please confirm this with them.

Since the work must be completed by the time of the inspection, some places will ask you to fill it in, and in other cases, the inspector may want to check it.

And the best tool for digging is a spoon!

Use a metal spoon to thoroughly scoop out the contents.

You can easily create access holes!

That's another story.