/diy/ - Do It Yourself

[Anonymous No.2903834]

Im doing a general labor job and the project manager himself was out in the site using a mag to float some mud. He was trying to teach me about magnesium chemical reaction with concrete. I did concrete for a year and i noticed that he hadnt stripped the coating off of the magnesium float and said that he wasnt using magnesium till he stripped the costing off his mag and he told me he did 15 years and you dont strip the outer coating off a mag
Im so confused bros. Which one of us is retarded?

[Anonymous No.2903874]

Isn't the point of the mag float just that it's a hard, smooth surface? I think the suction of water and the mag draws a lot of the portland to the surface. This gives you a nice finish at the cost of weakening to surface cracks.

[Anonymous No.2903879]

>>2903874
From what i was taught, the point if magnesium is it causes a chemical reaction to draw up the water and that to expose the magnesium you have to strip the outer coating shit off the mag. Any tine i bought a new mag id scrape that coating off in the dirt before using to expose the metal beneath.

[Anonymous No.2903904]

The coating if there is any will be worn off after troweling very much at all. The mag surface is kinda rough or coarse and that is what brings the cream to the top. Feel the surface of a mag trowel vs a steel trowel and you will see what I mean.

How would it be a chemical reaction or draw the water to the magnesium? Wouldn't the chemical reaction be saturated with water immediately rendering it useless? If you put a mag trowel in a bucket of water does it absorb all the water and ruin the trowel? Come on man...

[Anonymous No.2903906]

>>2903904
>would it be a chemical reaction or draw the water to the magnesium? Wouldn't the chemical reaction be saturated with water immediately rendering it useless? If you put a mag trowel in a bucket of water does it absorb all the water and ruin the trowel? Come on man...
Confused by your post. Typically you start off with fiber when its wet but 8f you want to "cream it up" you use the mag. I never said anything about absorbing water. It definetly draws water up for sure.
Youre probably right about the acidic concrete eating through that shit pretty quick though.

[Anonymous No.2903909]

Found this
>when magnesium floats on water, it's due to a chemical reaction between the magnesium and the water, producing hydrogen gas bubbles that cause the magnesium to float.
Here's a more detailed explanation:
The Reaction:
Very clean magnesium ribbon has a mild reaction with cold water, forming magnesium hydroxide (Mg(OH)2) and hydrogen gas (H2).

[Anonymous No.2904030]

>>2903906
I'm saying it is not a chemical reaction that brings the water and cream of the concrete to the surface, rather it is the rougher surface of the mag trowel that does it. They used to use wood floats for the same purpose... Steel slicks off the top of th surface. A rough mag float pushes larger stuff down and brings the cream to the surface. That is all it is. No magical chemical reaction or other voodoo bullshit.

My post was to get you to think about what a chemical reaction even is. Do you think a magical mag float that draws water up through concrete wouldn't draw up water from other sources or even the atmosphere until all the chemical reaction was used up? Wouldn't they sell mag trowels as a one time use deal in vacuum sealed bags if that were truly the case?

[Anonymous No.2904033]

>>2903834
I don't think there's any chemical reaction taking place. A magnesium float can have some density to it making it heavy enough to effectively float concrete that is setting up while also being smooth enough not to gouge the surface like a wooden float can do at that stage.

[Anonymous No.2904111]

>>2904030
>>2904033

>>2903909

[Anonymous No.2904115]

>>2903834
I think that’s all nonsense.
However, there probably is a reaction that will eventually pit and damage your float.
Magnesium is similar to aluminum (and, in fact, alloys together well) but I had cast aluminum floats back in the 70’s.
Magnesium is good good for the same reasons they use magnesium base plates on circular saws. No other reasons.
If you see what lye (a base) does to aluminum, you’ll understand what the highly basic cream water from the cement is slowly doing to your mag float.

[Anonymous No.2904139]

>>2904115
You have one thing right. Anyone who has done concrete before knows that the chemical reaction will slowly fuck your mag. The left is a new mag and the right was only used for a few months. I have one around here i used for a year and its sloped upwards and half the thickness

[Anonymous No.2904144]

>>2904139
>the chemical reaction will slowly fuck your mag.


You sure that's not just the abrasive nature of the concrete wearing the magnesium out?

[Anonymous No.2904175]

>>2904144
Hehe

[Anonymous No.2904436]

Magnesium isn't used in floats because of the reaction, it's used because it's a lightweight metal.
Same with magnestium circular saws. You're not going to get a chemical reaction with the metal you're cutting. It's just a lighter circular saw to handle.

[Anonymous No.2904572]

>>2904436
>because it's lightweight
holy shit this. this thread was giving me an aneurysm.
why are concrete guys so fucking stupid.

[Anonymous No.2904769]

>>2904111
I'm not a scientist but i really struggle to see how that is applicable to floating concrete.

[Anonymous No.2904870]

Everyone ITT didnt know they had to strip the outer coating off the mag lol

[Anonymous No.2905026]

>>2904870
Lol, yeah, … exactly. Even though it’s very difficult to do, my 53 page manual for my mag trowel says you need to strip off the paint. You have to be careful, though, it might get so light as to float away

When I got a new tesla, I made sure I stripped off the paint, so it makes the car lighter by forming hydrogen bubbles on the surface. Otherwise, the car probably won’t move, but I’m no chemist… I’m a concrete guy.

[Anonymous No.2905298]

>>2905026
Maybe humble yourself and realize there are things to know about the simplest jobs and maybe do some research on a tool before using it for the first time. If you google it, google will instruct you to remove the outer coating to use the magnesium alloy

[Anonymous No.2905334]

>>2904033
>A magnesium float can have some density to it making it heavy enough
If the point is to be heavy, magnesium is one of the worst materials to use. The only metal less dense is beryllium.