Solder paint

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steve howe
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Solder paint

Postby steve howe » Wed Jul 29, 2020 4:58 pm

Can anyone suggest a flux/solvent that will re-activate Carrs 179 solder cream? I have had a tube of the stuff around for yonks and not used it much until recently having discovered the joys of the RSU. The stuff in the tube is pretty dried up and solid and I'm wondering what might render it soft again. I'm guessing its made with resin based flux because a few crumbs scraped out won't mix with water.

As its not cheap stuff I'd like to save it if I can.

Steve

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David B
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Re: Solder paint

Postby David B » Wed Jul 29, 2020 5:43 pm

I gave up on solder paste/cream some time ago because for one thing it does have a shelf life but I also found it splatters and spits with the RSU. I find tinning parts to be very effective but sometimes either add small pieces of solder cut off the reel or added with a conventional iron (like tacking) and finished with the RSU.

I know some people do get on with cream/paste but I have yet to find the secret.

ColinMcC
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Re: Solder paint

Postby ColinMcC » Wed Jul 29, 2020 6:41 pm

I think that you can use one of the non-acidic fluxes, either Carrs orange or yellow. Unfortunately, I can't remember which. The answer, if I recall correctly, is in the Carrs Soldering handbook - it was a long time ago that I used to work part time for one of our tool suppliers.

Daddyman
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Re: Solder paint

Postby Daddyman » Thu Jul 30, 2020 5:44 am

I've mixed Carr's Yellow with London Road's paste, but am unable to give any idea of how it performs for the reasons David outlines...

Albert Hall
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Re: Solder paint

Postby Albert Hall » Thu Jul 30, 2020 6:52 am

ColinMcC wrote:I think that you can use one of the non-acidic fluxes, either Carrs orange or yellow.


Yellow is dilute phosphoric acid so it will be orange. I can't remember what it is made up of but the main ingredient was an obscure chemical which I'm sure was not an acid.

Roy

charleswrigley
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Re: Solder paint

Postby charleswrigley » Thu Jul 30, 2020 8:16 am

My 1991 edition of the Carr's Soldering Handbook is not specific but it says that Solder Cream is based on resin fluxes. It goes to say that Orange Label is a semi-synthetic resin flux therefore it would seem indeed that it would be appropriate.

An interesting experiment because in my experience when solder cream becomes rock hard goes off and seems impervious to any form of revival.

Charlie

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Guy Rixon
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Re: Solder paint

Postby Guy Rixon » Thu Jul 30, 2020 10:02 am

If the flux in the paste was a solution, then would it not be sufficient just to add water?

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David Thorpe
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Re: Solder paint

Postby David Thorpe » Thu Jul 30, 2020 10:41 am

My experiences using solder cream and an RSU have been exactly the same as David B's above. I now avoid using it.

DT

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steve howe
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Re: Solder paint

Postby steve howe » Thu Jul 30, 2020 11:08 am

Guy Rixon wrote:If the flux in the paste was a solution, then would it not be sufficient just to add water?


I tried various liquid fluxes that I had to hand and none mixed, however when I pulled the plunger out of the syringe I noticed a distinct whiff of Isopropyl...so I added a few drops and poked it about with an old screwdriver and it appears to have returned to a semi-liquid. Once I had unblocked the steel tube and flushed it through with IPA, all seemed restored. Cleaning the tools afterwards did show that the solder had a 'greasy' nature resistant to water, suggesting resin based flux. I haven't tried soldering with it yet, but I agree with David B's comments above, its not necessarily the best stuff for RSUs and tinning is probably the cleanest way of going on.

allanferguson
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Re: Solder paint

Postby allanferguson » Thu Jul 30, 2020 3:52 pm

It may not be entirely relevant, but I have had a tub of Carrs 188 solder paint for many years. Some years back it had gone fairly solid, so approached Carrs for advice, and was told to use Carrs Green Label flux, which certainly worked at the time. I've never used Green Label for anything else, and I've no idea how it's formulated. Might be quite irrelevant for solder cream, though.

Allan F

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johndarch
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Re: Solder paint

Postby johndarch » Thu Jul 30, 2020 5:02 pm

I must be the odd one out. I have been using Carr's No Clean Solder Cream for years with my RSU and have never had problems with spitting. Now, I have to admit that I do mix it with a little Powerflow Flux prior to applying it to the surface to be soldered to help it flow. I also have to say that I use my RSU for most of my soldering from chassis building to fiddly bits.

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barrowroad
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Re: Solder paint

Postby barrowroad » Thu Jul 30, 2020 6:28 pm

I have to agree with John. I have used Carr's No Clean Solder for a long time. The brasswork roof on Barrow Road Shed was assembled using it and an RSU. I have also used it on riveted track using a soldering iron.

Robin

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David B
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Re: Solder paint

Postby David B » Thu Jul 30, 2020 6:52 pm

Solder cream/paste/paint seems to be like Marmite - love it or hate it. How is it some people get on with it and others do not? What's the secret of its successful use?

I bought a syringe of the cream many years ago and it lasted perhaps 18 months before it went solid. I remember commenting on it to Brian Lewis who said it needed using as it had a limit to its life. I had used only a small proportion so wasted most of it - 90%? - and felt that having been bitten, I would not buy the stuff again. It was about £16 a syringe then; now I see it is £31.

I also have a jar of solder paint which I have never managed to use successfully. I shall stick with the reliable solid stuff straight off the reel.

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johndarch
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Re: Solder paint

Postby johndarch » Thu Jul 30, 2020 9:10 pm

As I use the solder cream on a reasonably regular basis. If used properly, the amount needed to build an etched loco kit, for example, is quite small so a syringe probably lasts me several years and I have not had any problems with it going off to date.

By the way, I LOVE marmite, especially on hot buttered toast!


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