Any possible additives to a drain cleaner I use as a source of NaOH? It is in pellets. And the box says main ingredient $\ce{NaOH}$ at least $30\%$ (I hope it's more). The box also says "aluminium catalyst". My goal was to take these pellets and dissolve them in water so that I would make a $1\textrm{M}$ solution of $\ce{NaOH}$.

I set everything up and most of it refused to dissolve in the solution. And the solubility for $\ce{NaOH}$ is pretty high. So I added some heat.This made almost everything slowly dissolve. Another thing was these small aluminium bits seemingly reacting and going up and down in the solution. I'm not sure if there was any gas released, but the solution definitely was not still.

I filtered it to remove the small aluminium balls. Any ideas If I have a relatively pure solution of $\ce{NaOH}$, or is it full of some other drain cleaner components. It is transparent-whiteish-little-yellowish. Filter kinda yellowish too.

What could these other components be?

Thanks
The product you've described contains the following ingredients (per the ingredient data sheet on the manufacturing company website):


Sodium hydroxide
Sodium chloride
Aluminium
Mineral oil


One possibility is that the aluminium is there to provide a foaming action, as its oxidation in the presence of aqueous sodium hydroxide liberates $\ce{H2}$ gas, per the following reaction (source):

$$\ce{2Al + 2NaOH + 2H2O -&gt; 2NaAlO2 + 3H2}$$

The aluminium and sodium hydroxide would need to be kept separate and relatively anhydrous in the bottle to avoid reaction, so I wonder if the purpose of the mineral oil (which is hydrophobic) is to act as a moisture barrier and prevent mixing. If this is indeed the reaction that occurs, then the hydrated aluminium salts present are going to be at least somewhat soluble in solution, so I think it's improbable that what you have is pure sodium hydroxide. That said, if the quantity of aluminium is indeed small, this might not be a problem for your purposes.