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Author Topic: Another Primer Question  (Read 1983 times)

ukmike

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Another Primer Question
« on: January 17, 2022, 04:09:14 pm »

Hi All.


I need to paint some Brass handrails and Pulpit Rails, mostly silver soldered 3.5mm round solid rod.


Have tried the the usual offerings but non of them mention Brass in their data sheets.


It really needs something containing an acid, probably sulphuric.


Any suggestions most welcome.


Here's a picture of the hand rails, one virtually finished and the one before finishing.


Mike.
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RST

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Re: Another Primer Question
« Reply #1 on: January 17, 2022, 07:43:38 pm »

Hi,


Try having a look through Stan's Grand Banks build thread.  I believe he's also taken time to post otherwise about a primer for brass.  Might want to look at Taranis's (Andy's) posts also as he seems to get on fine with his choice.  I tend use U-Pol Acid 8 which works often enough on brass for my uses (not always though) but I'm no fine-scale modeller compared to allot of folk these days!


Rich
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ukmike

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Re: Another Primer Question
« Reply #2 on: January 17, 2022, 08:12:11 pm »

Thanks for the info Rich.


Have checked with U-Pol already and they don't mention Brass in the specs sheet and they haven't tried it.


I suppose there isn't a big enough market for manufacturers to produce it.


Mike

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RST

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Re: Another Primer Question
« Reply #3 on: January 17, 2022, 08:15:50 pm »

Hi Mike,


That's why I added the comment about it.  I have it left overs from working on cars so until it runs out, it works often enough for me.  Both the others have alternatives that work also.


...how do you fix those parts though? Have you got any "nubs" to fit in drillings?


Rich
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essex2visuvesi

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Re: Another Primer Question
« Reply #4 on: January 17, 2022, 08:31:42 pm »

Thanks for the info Rich.


Have checked with U-Pol already and they don't mention Brass in the specs sheet and they haven't tried it.


I suppose there isn't a big enough market for manufacturers to produce it.


Mike


Upol Acid etch 8 works great on brass.  We used it on my Showmans engine kit.... not cheap tho
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ukmike

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Re: Another Primer Question
« Reply #5 on: January 17, 2022, 08:43:09 pm »


Rich.


The 3 contact points are drilled and tapped M2 and bolted thru' using machine screws from the inside of the

flying bridge.

I can't afford to blow money on stuff that MIGHT work, so, I'm going to make my own using diluted sulphuric

acid and couple of other ingredients including a colourant, maybe Cream. On test pieces first of course.

Mike.
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RST

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Re: Another Primer Question
« Reply #6 on: January 18, 2022, 01:40:23 am »


Upol Acid etch 8 works great on brass.  We used it on my Showmans engine kit.... not cheap tho
Thanks,
Good to hear, the OP has the other two contacts as options also.
Rich
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ukmike

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Re: Another Primer Question
« Reply #8 on: January 19, 2022, 04:41:53 pm »


Hi number 1.

Have already spoken to Genolite,(very helpful people), and they say that their etching primer is the one that may work, but pointed out that Brass is the most difficult


metal to etch.


Rust Oleum, I know nothing about, but, I would have thought that were it any good someone would have said before now.


I am in the process of making some myself and should it work I'll post the results.


Mike.
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Subculture

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Re: Another Primer Question
« Reply #9 on: January 19, 2022, 09:59:14 pm »

Are the railings bonded into the model? If not you can etch them with some ferric chloride and then paint them with any primer you like.
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ukmike

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Re: Another Primer Question
« Reply #10 on: January 20, 2022, 12:04:56 am »


Are the railings bonded into the model? If not you can etch them with some ferric chloride and then paint them with any primer you like.


Hi Subculture.

Many thanks for the suggestion.

The handrails are easily removable, as they are screw fastened.

I thought that Ferric Chloride was used to etch designs,name plates and the like onto Copper or Brass, also making PCB's.

This is  achieved by material loss, I don't want to remove material, just chemically 'roughen it up' with the loss of only a few microns overall.

Mike.
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Subculture

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Re: Another Primer Question
« Reply #11 on: January 20, 2022, 09:00:02 am »

It's an etchant. You don't leave the railings in their for hours, a minute or two is usually enough, just so that the finish of the parts looks totally dull and matt, then rinse of in fresh water, degrease and paint. The softer the metal, the less time it needs, for instance white metal fittings only need a few seconds in the acid to turn them from silver to a very dark grey, almost black.


The etchant will put millions of microscopic craters in the metal giving the primer something to cling to. You won't see this in the painted finish. Try it out on some scrap material first, if you're nervous, but you needn't worry, you won't dissolve your parts unless you leave them in overnight or something silly. You can keep the etchant in a jar and reuse it over and over.

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ukmike

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Re: Another Primer Question
« Reply #12 on: January 20, 2022, 09:49:53 am »

Good Morning Subculture.
That's the very result that I'm looking for, many thanks for the info.
I'll get some and as you suggest try it on some scrap pieces first.

The Pulpit is the tricky bit as its quite large and fiddly, too big to put in a bath, so what do you think about painting it on with a brush, possibly diluting the ferric chloride
a little as it will take a while to paint it all.

Here is a photo of the Pulpit to show what I mean. It's approx. 500mm x 350mm at the widest. 3.5mm top rail and 2.5mm uprights all silver soldered,no soft solder.

Mike.
 
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Subculture

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Re: Another Primer Question
« Reply #13 on: January 20, 2022, 10:12:08 am »

Brushing will work better than dipping as the mechanical action helps the etching process. If you haven't used it before be warned that ferric chloride will leave stains on anything it touches, and the smell is quite pungent, so it's a job for the workshop/well away from the house and wear old clothing on you don't care about.

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Taranis

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Re: Another Primer Question
« Reply #14 on: January 20, 2022, 02:09:26 pm »

Even the late DaveM acknowledged that Tamiya "FINE" primer for plastic and metal works exceedingly well on brass.


All of my models have been done with either light grey or white but must be the FINE not ordinary version.


It doesn't come off


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tonyH

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Re: Another Primer Question
« Reply #15 on: January 20, 2022, 02:41:11 pm »

I've got into the routine of leaving brass fittings in a jar of dilute citric acid prior to etch primer. Whether it adds anything or not I've no idea but it works for me.....at least as far as I'm aware :-)
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JimG

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Re: Another Primer Question
« Reply #16 on: January 20, 2022, 08:38:50 pm »

Vinegar should also do this being an acid although might need longer as quite dilute. Even Cola might do as it generally contains phosphoric acid (why it cleans metals so well).
Jim
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Taranis

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Re: Another Primer Question
« Reply #17 on: January 20, 2022, 10:11:05 pm »

Tamiya has decades of experience with photo etched parts and their FINE primer is made specifically for highly detailed kits with brass.


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