Filler or solder ?

[utopia]

The spare tank that I've just bought to try a new paint scheme on has a couple of very minor dents.
They would be easy to hide with ordinary filler, but I have a (probably unrealistic) fear that, having done all the paint-work, the filler might drop out one day and ruin all the hard work.
I have heard that in the past it was accepted practice by some, up-market manufacturers to use solder to build up and reshape/match ill-fitting car body panels. This would seem like a more secure/reliable method for dealing with minor issues such as I have.
Does anyone have any experience of this ?
I imagine I'll still have to use a thin, final levelling smear of filler, but I was hoping to avoid anything much thicker than that.

My main concern is that filler or primer may not bond well to the lead/tin solder.
I know its possible to get primers specifically intended for metals other than steel, but I have never used them before, so I don't know how good they are, or whether they only really work on certain metals and not on others.
Solder certainly "feels" kinda greasy...like nothing would stick that well to it.

Would be grateful for any advice.

Now I'm off to empty my old tank.... dry roads..that'll be the B6047, then. :woot:

[Kato]

Crikey not done that for years, its not that straight forward and if not done properly will is much more likely to fall out than normal body filler, anyway here goes....:scratch:

Clean the tank of all paint, rust, dirt and grease by using a sanding disc or wire brush to work the metal until it is clean and bright, make sure it is well keyed
Apply some solder and tinning flux, which is very caustic so you might want to be a bit careful with it. Use a wire brush or steel wool followed by a clean, dry cloth to wipe off any remaining excess. The process helps remove any and all surface contaminants and prepares the surface for tinning.

Use a tinning butter, which is a thick compound composed of tin powder and a zinc chloride, before applying your lead by warming up the tinning butter compound with low heat from a short flame and then completely mixing the contents prior to application. Using an oxyacetylene torch on low flame, or propane torch, heat the surface of the area where the tinning butter will be applied and then use a brush, to apply the compound to the surface to be filled, ensure a little bit of overlap from where the lead will be applied. Once the area is covered, use the torch to warm the surface compounds until the tinning butter turns to a brownish foamy residue and then immediately wipe off the surface from bottom to top with either steel wool or a clean, cotton cloth. This will leave a silvery exterior showing that the surface has been properly tinned and is ready for applying the lead.

Apply the lead and use a torch to keep the surface warm while the lead is applied to the surface and the end of the lead is heated. The lead is applied until there is a sufficient amount to fill the work area. Try to not overheat the tank because it will start to warp, stop and allow the surface to cool occasionally. Once the lead is on the panel let it stay warm enough to maintain a semi-solid condition and then use a wooden paddle to shape the lead by dipping the wooden paddle in tallow or beeswax to keep the lead from sticking. Allow the surface to cool naturally, then finish shaping with a file and sandpaper, if you get right you shouldn’t need to use filler after that just prime and pant…..HAVE FUN :mand:

[Gordon H]

Blimey!!!!!!!

[satan916]

Jeez, think I need to sit down after digesting that lot! If it was me I'd use filler

[gary tompkins]

P38 is normally flexible enough to prevent drop out, provided you prepare surface well and score it to give it a good key to bond with.

Alternatively.. what about giving this stuff a go? Dinitrol is claimed to give a stronger and more flexible repair than a standard body filler.

http://www.frost.co.uk/item_Detail.asp?productID=8311&frostProductName=Metalised+Body+Filler+(2+kg)

[Kato]

As Gary says P38 is good stuff..........

[He11cat]

What would an accident repair place use , filler probably I guess.
But if you want to try something different well why not!
Rather brave but I'm sure your capable .

[Chris & Nean]

A good xplanation Kato, I welded lead one time fabricating vented tiles for my roof, it was nice to be able to weld and meld this metal at low temprature, I used ordinary plumbers solder it worked well.

[Nickj]

I've only used metalised epoxy where I've needed to drill and tap for some reason like rebuilding the water pump walls in a KTM I had. I'd just go for plain epoxy filler if you prep the surface well it it's not going to fall out.

[Dookbob]

I have repaired the bottom of fuel tanks with the solder method, but to be honest I have also filled dozens of dents in tanks and car panels with body filler( I like P38 too same as gary mentioned) I have NEVER had filler fall out of anything. Just rough up the surface and slap it on, then give it as long as you have time for , to allow it to shrink before the final rub down. Quick , cheap , easy , go for it.

[manwithredbike]

i like my wee dent just as it is

[damien666]

I use Plastic Padding ' Ultima' every day at work. Never had a problem.......ever! with it. The powers that be, ie management have over the years tried to relace it with other types of filler, which have always been crap in comparison. It's easy to apply/spread, dosn't crack or shrink and has good flexible properties. Just make sure you use a clean filler spreader card every time and mix it up on something that can't absorb moisture ( not cardboard etc), and blow any dust away inbetween skims with an airline.

[utopia]

Thanks everyone.
In particular, Kato...your response was, once again, the full Monty...and then some.
I had done a functional, though not exactly pretty, temporary repair to the holes in the base of the tank on my Dominator, using soldered, thin copper sheet, which was what got me thinking about it in the first place.
I must admit, I was only considering a much simpler process using a tub of rosin and some multicore.
Looks like it will probably be the filler after all, though.
Curiosity satisfied, flight of fancy grounded, common sense restored. Thanks.