Hairline crack in gold chalice

Hi, I am new here and also very new to working with precious metals. I am a knife maker and welder so I know my way around metal work, even intricate things but have never worked with gold.
I have been asked to repair a hairline crack in what I am almost sure is a golden chalice. It is at the base of the cup where it meets with the stem.

My questions are, how can I better tell what material it is and how should I go about the repair?

From my research, I am thinking the best route would be using easy solder paste and a torch. I also see that I should get it very clean, what is the best way to clean it?

Any and all pointers are appreciated my. If you think I'm crazy for attempting this, let me know :D

Thank you!

Hi John welcome to the forum

I think you’re crazy if you think it’s good and you’ve never done anything like this before! If you think it’s gold then I’d weigh it and look at today’s gold price just for scrap value never mind what it might be worth as a chalice and decide whether you want that responsibility.
Are there any assay marks or any marks at all to give you a clue? It may even be gold plated and that’s another thing altogether. Lots to think about before considering how to go about the repair

Definitely a lot to think about. I don't currently have the chalice and I haven't seen it yet so we'll see if there are any marks, but it is either gold or gold plated.

It being a sacred vessel of the Catholic church, repair is always the first option as many factors come in when scrapping/disposing of it. It's monetary worth comes last.

I have been asked to do whatever I can even if we come to the conclusion that I can't repair it. They came to me as I have a good bit of experience with casting, soldering and metalwork in general.

I realise that the monetary value to the church doesn’t matter but it’s important if the person repairing it doesn’t have the experience and you are liable. Do you have insurance to cover it?
Will be interested to see any markings once you see it.
My point about scrap was misunderstood as I wasn’t suggesting that they scrap it just an indication of its value in precious metal not knowing anything else about it

He told me he was perfectly willing for me to experiment on it.

Definitely, makes sense. That is something, along with the markings that I will look into once I have the piece.

Now, those complications aside, although they are crucial, is there a normal procedure to repairing a crack in gold or gold plated silver?
Am I correct in thinking that soldering would be the way to fix it?
Thank you again for your time

Soldering would be the way to fix it, however it is not quite that simple, there are most likely more experience on the forumwho can advise you, here is what I know, solid gold you will need tp anneal the entire piece to to help alleviate stress distortion, depending on the construction you may have to disassemble to do a quality repair, you will have difficulty matching the colour try to use the same grade of solder as the chalice is e.g. 9-18-24 etc. Gold plated silver (highly unlikely with communion ware) you will need to use silver solder and obviously will need to have the item plated, Just so you are aware just a basic Chalice would be several thousands dollars to purchase.
If you are not experienced with soldering precious metal I would practice first.

If the item is precious metal, rather than solder I think I would advise laser welding; less heat involved, less risk of further damage, easier to clean up after but a specialist could provide better knowledge.

Obviously the first thing is to establish what metal you are dealing with.

The use of paste solder to infiltrate the crack is a recipe for disaster, because if it fails to flow in, the cleaning up would be very challenging.

If found suitable for Laser welding, as suggested by Les, the expert will also see to the preparation.

If the crack is where the stem meets the bowl, it is likely to be a solder joint which is failing, and might be best parted completely, before re-fixing.

What ever the method of repair, it is likely to need plating to restore it as new.

I see it as the proverbial poisoned chalice, best avoided. Dennis.