New Laser Cutter Material Appoval Request: Drywall

Hi there,

I’m looking to laser some drywall … clean, unpainted, drywall. I am actually just wanting to cut the paper on the drywall so that I have some nice clean sharp lines to cut with a knife. Cutting the actual drywall with a laser would be bad for my application as drywall has moisture in it that acts as a fire retardant, through evaporative cooling in a fire, and provides structural strength. My expectation is that a couple of passes on the Heavy Paper power setting, 20%, will do the job while keeping the drywall temperature below 100°C (except at the surface transition between the paper and the gypsum interior).

MSDS sheets for drywall are tough to find, but I’ve located:
http://www.commercialdrywall.com/files/products/liftlite-drywall.pdf from Continental Building Products in the US.

For full disclosure I must point out the following … (I know TMI) …

The major component of drywall is Gypsum which has a melting point of about 150°C and a boiling point of about 1450°C. INCHEM, the International Chemical Safety group (associated with the WHO) lists Gypsum as “Not combustible. Gives off irritating or toxic fumes (or gases) in a fire.” (see ICSC 1215 - GYPSUM (MINERAL)) I have looked around and found no further discussion of combustible by-products although my expectation, from my University chemistry daze, of the process is Gypsum (CaSO4·2H2O) when heated leading to it’s melting point, probably around 100°C begins to give off it’s water leaving behind calcium sulphate (CaSO4), i.e. plaster, to melt around 150°C. Above 1500°C (the boiling point) I would expect that the gaseous Calcium Sulphate chemically breaks down and various sulphur oxides, SOx, are produced. These are generally bad as they are chemically reactive and I further expect that they will readily combine with the moisture in the air the to produce: Calcium Hydroxide, Ca(OH)2; Hydrogen Sulphide, H2S (that rotten egg smell); Sulphuric Acid, H2SO4; and probably lots more stuff depending on what’s in the air.

Wait… you’re saying drywall isn’t DRY!?!? I know naming things is hard, but we can do better than that.

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What kind of shapes/patterns are you looking to do?

Looking to make a slotted grill pattern that i can chip out of the drywall to make a flush mounted bathroom ventilation fan cover.

Hi Pat:

Apologies for the long delay in getting back you.

It appears that the LCC is unable to respond at this time.

Hopefully someone can reach out to you regarding this matter.

Mark

Thanks for the update Mark. This is now an academic exercise, in case someone wants to do this in the future. I’ve made a wooden template for my project.

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