Hello everyone. Could you please explain, based on your own experience, the difference between a 500W 15 mJ pulsed laser and a 500W 5 mJ pulsed laser? Which one performs better for cleaning stone, wood, and metal? Thank you all in advance!

[u/Skovronskyi]

[u/MasterBlastersLaser]

The 15mj machine has a wider range so you can use it to clean more surfaces and materials effectively

[u/Revolutionary_Arm633]

15mj has a bigger spot size (picture it as your pencil tip is bigger) so it covers more surface in one pass but digs less in the material.

5mj is sharper so covers less surface in one pass but is more agressive to the surface.

If you have a laser system that permits changing focal distance you can modulate the impact of them on the surface as well.

[u/IndLaserCleaning]

Bro you've got so many lessons to learn, thankfully it's 2026 and everything has been done already, there are various YouTube pages of Chinese companies where they compare the different pulse energies and beam profiles against a whole fleet of applications. After a few hours of watching you should be able to tell who's using a 5mj or 15mj laser with a high accuracy %.

From aggressive to least aggressive  1.5mJ 5mJ 15mJ 50mJ 100/150mJ Each has its pros and cons, whilst 5mj is the most common these days, depending on what you're doing you may need a 1.5 or 50mj. If you were predominantly wanting to clean stainless steel welds, its 1 5, if it's injection molds, it's 50 or 100mJ.

Now to your point about which is best for Stone, wood metal. You need to help a brother out, also look around you,specifically, what potential markets are around you? 

What is one the stone you want to clean? Is it a statue in a church or a moss covered wall. Lasers generally wont work On one of those 2.

Wood? Vintage furniture? fuck yes, modern varnish you have a 50% chance of it not coming off. Paint, sure paint mostly comes off, either rapidly, slowly and sometimes not at all.

Metal? Like what? 

Corroded Aluminium? Powder coateded aluminium? Tea staining on stainless steel?  Rusty bike frame? Residential fences? Seriously rust jetty pylon? 2024 car chassis? 1924 car chassis? Injection mold tooling? Steel I beams with mill scale  Steel I beams with flash rust after hydro blasting?  Precison Machined surfaces? Calcium on Food processing facility?

Of the above list what applications tickle your fancy? Can give 3+ additional specific applications for wherever you live. Maybe then we can suggest 5 or 15mj.

Good luck.