So I got round to cleaning the font and it does not look good, it actually looks worse than bad. Can it be saved? Is this too much for POR15
There are about 25 cracks in total Looks like the Aida may never see the light of day. Don't suppose there is anyone near Wolverhampton (UK) who is able to hard solder this or is it too far gone for this.
@chocki You can try to flow epoxy resin in the fount pay attention to put some grease on the threads before it could be a good idea to pump in order to push the resin through the small cracks I saved several lamps with that
So far I have saved 5 x stress cracked founts with this: Epoxy Resin multi-purpose system 25 min (medium viscous) | HP-E25KL (You have to follow the manual very closely).
What about cutting out a flat ring of brass from some thin brass sheet which would cover the cracks and place flux powder and silver solder squares between the ring and font base and heat until it melts and flows.
Hard soldering spots while the rest of the fount is most likely soft soldered will be a challenge (to me at least).
I've used Epoxy to seal tanks and it works. I thinned it down with Meths or de-natured alcohol but you can use acetone I believe. Either way, it alters the consistency and makes it flow really well when you get the proportions right (trial and error). I poured it in and slowly swirled it around and around so it coated the whole inside with a layer of resin, but make sure you clean the tank first to remove any loose particles.
I'd use a high-power(>250W-300W) electric soldering gun, aqueous zinc chloride flux and some 50-50 or 60-40 or preferably the euthetic 63-38 soft solder. It works even when the metal is a little less well-cleaned. Even better when clean. When done correctly, believe it or not, you'd be able to immediately touch with your bare hands, any metal parts adjacent to the spot just soldered. It'd hardly heat up the rest of the originally soldered joints on the fount...and still gets the solder to perfectly wet the metal surface. Almost 'magical'. I find them even more efficient than a propane torch plus resin-fluxed electronic solder. Others might had experienced differently. The only downside, zinc chloride flux is corrosive to the metal. That's due to both it being acidic and the presence of chloride ions. Just be aware of this and clean everything including all surrounding areas after use. Otherwise, there'd be nothing but regret and a lifelong phobia towards acidic fluxes.
Anyone got any idea of the copper content of the brass in a Petromax / Aida fount as this is important if trying to soft solder, and is the original soldering hard or soft?
If by "hard solder" you mean silver solder then you'd be taking a sledge hammer to crack a nut. As far as I know they used soft solder and I've successfully cured quite a few leaking seams with flux cored electronic solder. Why is the copper content important ? I've never had any issues when using medium (melts 720 - 765 degrees C) silver solder to join brass nipples onto 1/8 inch copper tubing.
The original solder is pretty soft and has quite a low melting temperature range. Probably marginally higher than 60/40 electronic solder. Its more like a 50/50 plumber-type solder. Don't worry too much on its copper content. Almost any solder would still adhere to the brass if it is clean, well heated and properly done. Well, it'd probably be easier if it has a high copper content. It would be almost impossible to sil-braze or hard-solder the base without causing the original solder to melt and run off. I wouldn't bother with sil-brazing it. I'd say the zinc content in the brass is pretty high. Otherwise, it wouldn't have been susceptible to such stress-corrosion cracks.
My plan was to fill the fount with dry fine sand and pack it to provide support and help keep the heat local. Close the holes. The flat brass ring which would have to be cut in one place to allow it to be fitted past the base lip would be placed over the cracks with flux and silver solder squares in between. The whole fount would then be placed into cold water nearly submerged, this would keep the edge cold as the water boiled off as heat propogated to the outside, should actually stop the existing solder melting but this was assuming it was hard soldered. A section of steel tube (assuming I could find something that would be the correct size) would have been placed to press the brass ring down and keep the flame away from the sides. This would also heat and act as a giant soldering iron. Mapp gas braising torch would then be used to heat the new brass ring which would have melted the flux and silver solder and due to the steel tube pressing down, capillary action would spread this to fill the void. Allow to cool and all cracks covered, filled and reinforced. Or an I over thinking this?, beginning to sound like it.
It might be an overkill. You can still follow the plan but using soft solder instead of brazing alloy would suffice. To get silver-braze to work, you'd need to heat the target metal to red hot for the alloy to melt, wet, flow and adhere. That might seriously impair the integrity of the original soft-solder under the bottom rim/lip and create additional leak points. I've experienced that, and you bet, it was pretty messy. Yes, it would be good idea to cool the fount and rim by partially submerging the fount in water. That's even when using soft solder.
Hard solder idea abandoned, looks like soft solder it will be. Cracks are on the base brass only, nothing up the sides.
Yes soft solder if it was mine too much heat with silver solder. Do you think you could make a new base plate and solder it in as that would be best Or maybe just loads of solder over the cracks would suffice like this one here Cheers pete
Any recommendations for the best solder for repairing these cracks in the UK as getting Tix brand solder is nigh on impossible without being properly fleeced.
I would have thought any soft solder would be OK for this. Lead free solder melts at a higher temperature than lead based You probably be better with a propane torch too if you struggling to melt what you have. I used some old lead stick solder and a iron for repair in last post
This would be classic. I've used similar. Prevents any resin flux(if used) from catching fire from the direct flame of a propane torch. It guides the flow of the solder to the intended spots without causing the other areas to get overheated.
Yes sometimes a torch causes more problems and the iron gives a lot more control once you get the hang of it. Case of old ways are best in some cases. Cheers pete
