Liquid silicone sealant

[cydodimead]

I have a 20M run of 10mm x 10mm U shaped aluminium set into edge of a step. It currently has LED tape in it but needs to be replaced. That's the easy bit but I need to re seal the groove with clear/slightly opaque silicone sealant. Using the standard stuff in a gun is not only a pain but very difficult to get smooth on the top. I have looked everywhere for a liquid version or 2 part that I can pour in, let it level itself and set but can't find anything suitable. Does anybody know where I might source such a thing?

 

[theprinceofdarkness]

Polyester casting resin from arty shops, sets hard, but is a liquid. If the strip is not exactly horizontal any liquid will run down to one end.
Frank

 

[maltaron]

To get a clean finish with silicon in a gun fix masking tape each side of your channel, fill with silicon then smooth it with a wet finger. Remove the masking tape and the jobs done.

 

[cydodimead]

Maltaron- I would do this but 2 metres is using a whole tube of sealant. With 20 metres not only is it a lot of silicone but also a lot of smoothing which I don't think I will get perfect on the whole length. I hoping to just pour something in a leave it to set but Polyester casting resin will go hard where as I need to option to pull it up if I ever need to. I'll continue the search or end up on my hands and knees with masking tap and water.