Remove Silcone from Aluminium

[ac1951]

Anyone know how to remove silicone sealant from aluminium ?

I need to remove all the old mouldy sealant from my shower surround and have used Unibond silicone eater to clean off the shower tray and tiles but it explicitly states not to use it on aluminium. (probably because it contains Sulphuric acid) The shower surround has aluminium supports and they to have a bead of sealant down the whole length which I need to remove.

thanks in advance... Andy

[Dave]

Go and find your local steel stockist and ask if you can have some of the steel banding that holds the steel together. It is about 25 to a little more (less than 30) wide. Make sure that you can bend it to 90 degrees within a distance of 4 inches without it taking any shape. If it takes on a bend, then you have the wrong steel. Go back and try again.

Take it home and with what ever you have, shorten it to about 6 -7 inches long.

Wrap lots of tough tape around the end that will become the handle and make sure that your hand has no chance of contacting the metal; usually by wrapping the tape overlapping the end and then folding it over and then put another layer of tape over the whole lot.

Now take a file and make the cutting edge square.

Now file an edge on the top edge about the same angle as a chisel. I tend to make the chisel edge (bevel) on the same side as the folded over tape on the handle. This gives you the ability to pick up the tool and know which way up it is.

After you have filed the cutting edge, comes the vital bit. If you are right handed then you must put a very small radios on the left hand corner, the same way and angle as you put on the cutting edge. And preferably a much larger one on the other corner. (if you are left handed, it should be transposed

Once this is done, if you feel the back of the cutting edge with your fingernail, it will snag on the burr from the sharpening. It is absolutely vital that you get rid of ALL this, as this will be the cause of any scratches you leave on the ally.

To get rid of this, rub the tool as flat as can be on either a file or a sharpening stone, bevel side up.

Now you have the power to remove the silicon, keep the cutter very low, about 5 degrees and when it starts to 'not' cut, it needs sharpening again.

Don't try to get all the silicon out of the corners unless you are sure that they will get covered again

All this can be done with a chisel, but I didn't/could get my hands on when I made one at work. Apart from which, it would have been too thick for what I was using it for.

Dave

[ac1951]

Dave, many thanks for the comprehensive response .... I have to admit that I was thinking you were going to end by saying "tie the steel band around your wrist as a reminder never to try removing silicone from aluminium" :) thanks again Andy

[Dave]

Just remember to keep the angle as low as possible and practice on another piece of ally first. The angle should be as close to zero as is possible. If the cutting edge is sharp, you should not have any problem. Remember, if there is a burr under the cutting edge, it will cut into the surface you are trying to clean up and make a scratch. I have done this many times in the aerospace industry and never left a scratch when I learned the way to do it. Practice first and then dive in. Try to hold the blade in your hand, so that it is curved, so that the cutting edge is horizontal, this will/should get you under the sealant.

I doubt that you will have to get right down to all the metal, as you can normally use sealant over the top of traces of the last one.

Anyone care to comment?

Dave

[ac1951]

OK job done, I didn't use the metal band suggested by Dave but he set the idea. A combination of using disposable safety razors and a kraft knife held at a very shallow angle did the job...

thanks Andy

[Dave]

I am very glad to hear that :-)

Dave