in some cases like I think with aluminum the oxide layer is fairly good at transferring heat, sanding the areas so it's still a little rough will give a better area for the glue to stick to and makes the thermal surface larger, I guess just a light sanding then cleaning that off leave the oxide layer and just glue and go, I use thermally conductive epoxy from the same makers that make the good goo, like artic silver and the epoxy I think uses the oxide from aluminum as the heat carrying part of the epoxy. on some cheaper lasers that I have repaired where only epoxy from the start , I clean the old off, leave very slight scratches so the new epoxy has something to hold on to better
Remember Remember The 8th of November, When No One Stood, but Kneel, In Surrender
In a popular government when the laws have ceased to be executed, as this can come only from the corruption of the republic, the state is already lost. Montesquieu