So I have watched many videos and been practising. I am preparing to weld some patches on my campervan that were all down one side of the roof under the high top that I removed. Please see the photos. When I weld the manual states use gas mark 4. This results in bad pitting etc and porous as expected when not using gas. It only seams to work in full gas at mark 6. So do you think there is a problem with the valve? I am using a disposable bottle. When I weld some of them look correct as in smooth on full gas but there is black soot around the blobs which I have to keep removing with the wire brush otherwise it makes bad welds when filling in the gaps. Is it normal to have to keep cleaning off? Anyway it all seams a bit of a mess. Is my stickout correct as per photo? Is my clamp making good contact? It does not seam very meaty and not loads of contact with the teeth. I bought a new one but then lost it! Going to look for it this afternoon. How long is this disposable bottle going to last from Machine mart -its the 110l one. Can anyone recommend a place for a big bottle in the uk? What about this: https://www.gas-uk.co.uk/argon-5-10-litre.html It says it is for thin steel, it is 66£ before deposit. Do you think I need it, the holes on the van are all down the length of one side where the side meets the roof. If I buy a big one, what size is recommended? How long do these last, I know it is hard to be exact. Also since there is a deposit I do not want to get lumbered with loads of spare gas on return. Any advice welcome for the welding or gas bottles etc. This is my welder with 0.6mm wire: https://www.machinemart.co.uk/p/135te-turbo-mig-welder/ Also I think I need a regulator, any advice what to get or where? I am in Sheffield if you know places for gas, I will do some research now as well. Also I am practising in my cellar. Will it be a problem to weld outside, will the gas just disappear!! What I noticed was that after scrubbing it with the wire brush it didn't look too bad and it came up ok with the grinder but has it properly penetrated? It seams strong when I try to bend it. Cheers.