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#1
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Mechanically polishing brass that's pitted?
I've got items of door furniture (letter box, knocker etc) that are
made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT |
#2
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Mechanically polishing brass that's pitted?
Vet Tech wrote:
I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT if its a smooth surface - or was, simply emery it down to get level, then start on fine emery and T-cut or jewellers rouge or valve grind compound, THEN finish with brasso., |
#3
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Mechanically polishing brass that's pitted?
On 26 May, 20:50, The Natural Philosopher
wrote: Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT if its a smooth surface - or was, simply emery it down to get level, then start on fine emery and T-cut or jewellers rouge or valve grind compound, THEN finish with brasso., The letter box is flat/smooth so I guess the emery paper is OK but what grade would you suggest and could I use this with an orbital sander? The knocker however is a big ring with twisted sort of ribbing (sorry there must be a more appropriate description) so it might need different treatment. This is a real challenge. VT |
#4
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Mechanically polishing brass that's pitted?
On 26 May, 20:35, Vet Tech wrote:
I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Solvol Autosol (from Halfords) and a mop attachment for your drill. |
#6
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Mechanically polishing brass that's pitted?
In message , Bob Eager
writes On Wed, 26 May 2010 13:19:52 -0700, wrote: On 26 May, 20:35, Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Solvol Autosol (from Halfords) and a mop attachment for your drill. Funny you should say that. I just purchased some Solvol Autosol (brought back memories of the late 60s and motorbikes) And, by coincidence, I've just found half a tube of it which must be what, 30+ years old Those were the days eh? As long as you had a tube of solvosol, grease and hermatite, what more did you need ? -- geoff |
#7
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Mechanically polishing brass that's pitted?
On 26 May, 20:35, Vet Tech wrote:
I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT The Brass stuff will have originally been epoxy laquered, whose remnants are still as tough as old boots. I usually burn it off with a gas torch etc, before starting with the abrasives. |
#8
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Mechanically polishing brass that's pitted?
On 26 May, 20:35, Vet Tech wrote:
I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. Garryflex blocks, in a range of (coloured) grits. Also sold under the Roebuck name. Webrax / 3M / Mirka pads (like pan scourers with grit in) in brown (very fine) and grey (ultra fine) grades Rouge or tripoli block on a cloth or powered cloth wheel / Dremel felt bob. Lacquer with a methacrylate lacquer, nothing else on brass. (Rustins) Tilgear, Axminster et al sell this stuff. Don't use Autosol, it's expensive and too hard for brass. Don't use anything with ammonia (including Brasso) as it'll be shiny today, dulled tomorrow. As always, finish one grit before moving finer. Skipping grits too quickly is a waste of effort. Use the right lacquer. |
#9
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Mechanically polishing brass that's pitted?
"Vet Tech" wrote in message ... I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Put a magnet on it first, and feel the weight... Lots of 'brass' these days turns out to be plate when you get it (Screwfix for example did solid brass electric sockets for a while, but continued advertising them as the same when they were made of plate.). The pits are often holes that go down to the iron underneath on old stuff, and, on new stuff ally, and you don't want to rub the plate away getting down to the bottom of the pit. Assuming it is solid brass then you may first need to go over it with nitromors as it is often lacquered, and even if it isn't this will get off the ground in skin and grease too. If you do adopt chemical or heat methods watch out for the core metal of some of the old knobs: I got a shock when the grey metal (presumably zinc/magnesium) that took the square turning rod of one of mine melted and ran out - took a lot of fiddling to make a replacement - when I was trying to hurry old lacquer off... Then as TNP says, there really isn't much option but to choose the minimum grade of emery/wet or dry, that will enable you to rub down past the pits. Deep ones you may even have to start off with riffler files. Keep the scratches all going the same way with the first grade, then rub these scratches away by going at right angles with the next grade down; then at right angles again, and so down through the grades. When you have got down to 600 or 1200 - 1400 - depending on how much of a perfectionist you are - T-cut or similar metal polish in a circular motion will rub out the fine scratches that are left. If your pieces are easily detachable you may find it easier to polish with wet and dry under the tap with a dash of wash-up liquid now and again. In preparing metals for microscopic examination a polishing sloping surface with water running over several grades of wet or dry was used, followed by a final burnish on a diamond lapping wheel. Brasso and Autosolve and similar products don't really polish: they just fill in the finer scratches: which you can prove for yourself by wiping a so 'polished' surface with paraffin, which wipes the 'shine' back off. It is better to polish properly - by reducing scratches to the minimum acceptable size - and then oil your product, rather than go for a brilliant finish that will mark and pit after the first fingerprint or raindrop. For a real brilliant finish you will need a proper polishing mop or buffing wheel, for which you can get several grades of cutting 'soap' and jewellers rouge. But it would still be best to wipe the surface with an oily rag regularly afterwards. (Oh and it'll get v hot on a buffer so leather gloves are in order.) The irregular shape of your knocker would probably be best tackled with various grades of brass brush wheel, but you will need (as with the buffing wheels) to find a way to clamp your drill securely, or get a bench grinder/buffer - which is always worth having. Once you have cleaned it with the brush wheel, then you go on to the polishing soaps on the buffing wheel again. Keep different mops for different grades of buffing soap. *Don't* whatever you do, be tempted to use an iron brush wheel. If you don't want to tackle the mops and such, you can achieve a fair bit on irregular surfaces with, say, strips of towelling or bootlaces. and various grades of grinding paste. Hold the knocker in soft vice jaws and work the strips of cloth 'shoe shine boy fashion' through it with one end in each hand: you may actually find this easier than a pukka buffer in fact. Sounds hard, but it is actually satisfying producing a good polish: rather like getting that perfect sharp edge on a chisel or scythe. S |
#10
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Mechanically polishing brass that's pitted?
geoff wrote:
As long as you had a tube of solvosol, grease and hermatite, what more did you need ? A motorbike, and a patient girlfriend. |
#11
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Mechanically polishing brass that's pitted?
In message , The Natural Philosopher
writes geoff wrote: As long as you had a tube of solvosol, grease and hermatite, what more did you need ? A motorbike, and a patient girlfriend. Still got the bikes (enfield and BSA) seem to have got through a number of girlfriends since then, though -- geoff |
#12
Posted to uk.d-i-y
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Mechanically polishing brass that's pitted?
spamlet wrote:
"Vet Tech" wrote in message ... I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Put a magnet on it first, and feel the weight... Lots of 'brass' these days turns out to be plate when you get it (Screwfix for example did solid brass electric sockets for a while, but continued advertising them as the same when they were made of plate.). The pits are often holes that go down to the iron underneath on old stuff, and, on new stuff ally, and you don't want to rub the plate away getting down to the bottom of the pit. Assuming it is solid brass then you may first need to go over it with nitromors as it is often lacquered, and even if it isn't this will get off the ground in skin and grease too. If you do adopt chemical or heat methods watch out for the core metal of some of the old knobs: I got a shock when the grey metal (presumably zinc/magnesium) that took the square turning rod of one of mine melted and ran out - took a lot of fiddling to make a replacement - when I was trying to hurry old lacquer off... Then as TNP says, there really isn't much option but to choose the minimum grade of emery/wet or dry, that will enable you to rub down past the pits. Deep ones you may even have to start off with riffler files. Keep the scratches all going the same way with the first grade, then rub these scratches away by going at right angles with the next grade down; then at right angles again, and so down through the grades. When you have got down to 600 or 1200 - 1400 - depending on how much of a perfectionist you are - T-cut or similar metal polish in a circular motion will rub out the fine scratches that are left. If your pieces are easily detachable you may find it easier to polish with wet and dry under the tap with a dash of wash-up liquid now and again. In preparing metals for microscopic examination a polishing sloping surface with water running over several grades of wet or dry was used, followed by a final burnish on a diamond lapping wheel. Brasso and Autosolve and similar products don't really polish: they just fill in the finer scratches: which you can prove for yourself by wiping a so 'polished' surface with paraffin, which wipes the 'shine' back off. It is better to polish properly - by reducing scratches to the minimum acceptable size - and then oil your product, rather than go for a brilliant finish that will mark and pit after the first fingerprint or raindrop. For a real brilliant finish you will need a proper polishing mop or buffing wheel, for which you can get several grades of cutting 'soap' and jewellers rouge. But it would still be best to wipe the surface with an oily rag regularly afterwards. (Oh and it'll get v hot on a buffer so leather gloves are in order.) The irregular shape of your knocker would probably be best tackled with various grades of brass brush wheel, but you will need (as with the buffing wheels) to find a way to clamp your drill securely, or get a bench grinder/buffer - which is always worth having. Once you have cleaned it with the brush wheel, then you go on to the polishing soaps on the buffing wheel again. Keep different mops for different grades of buffing soap. *Don't* whatever you do, be tempted to use an iron brush wheel. If you don't want to tackle the mops and such, you can achieve a fair bit on irregular surfaces with, say, strips of towelling or bootlaces. and various grades of grinding paste. Hold the knocker in soft vice jaws and work the strips of cloth 'shoe shine boy fashion' through it with one end in each hand: you may actually find this easier than a pukka buffer in fact. Sounds hard, but it is actually satisfying producing a good polish: rather like getting that perfect sharp edge on a chisel or scythe. S Superb article. Should be in the wiki. |
#13
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Mechanically polishing brass that's pitted?
"Bob Eager" wrote in message ... On Wed, 26 May 2010 13:19:52 -0700, wrote: On 26 May, 20:35, Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Solvol Autosol (from Halfords) and a mop attachment for your drill. Funny you should say that. I just purchased some Solvol Autosol (brought back memories of the late 60s and motorbikes) and I have a Dremel with suitable attachment. For exactly this purpose. I just don't have the circular tuit right now. Not polish: wipes off with paraffin and if you don't oil it you end up having to grind off the marks made next time it rains. I ruined the finish on my Ducatti with the stuff before I realised, and went for anodising and wax instead. S |
#14
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Mechanically polishing brass that's pitted?
wrote in message ... On 26 May, 20:35, Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT The Brass stuff will have originally been epoxy laquered, whose remnants are still as tough as old boots. I usually burn it off with a gas torch etc, before starting with the abrasives. Yup, but watch out for those melty centres - see below... S |
#15
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Mechanically polishing brass that's pitted?
"Andy Dingley" wrote in message ... On 26 May, 20:35, Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. Garryflex blocks, in a range of (coloured) grits. Also sold under the Roebuck name. Webrax / 3M / Mirka pads (like pan scourers with grit in) in brown (very fine) and grey (ultra fine) grades Rouge or tripoli block on a cloth or powered cloth wheel / Dremel felt bob. Lacquer with a methacrylate lacquer, nothing else on brass. (Rustins) Tilgear, Axminster et al sell this stuff. Don't use Autosol, it's expensive and too hard for brass. Don't use anything with ammonia (including Brasso) as it'll be shiny today, dulled tomorrow. As always, finish one grit before moving finer. Skipping grits too quickly is a waste of effort. Use the right lacquer. All seconded, save the lacquer bit: always looks better polished and wiped over regularly with oily rag. Or you'll be repeating the whole process again before long. S |
#16
Posted to uk.d-i-y
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Mechanically polishing brass that's pitted?
geoff wrote:
Funny you should say that. I just purchased some Solvol Autosol (brought back memories of the late 60s and motorbikes) And, by coincidence, I've just found half a tube of it which must be what, 30+ years old Those were the days eh? As long as you had a tube of solvosol, grease and hermatite, what more did you need ? If there's one thing that I like It's a burn up on my bike A burn up with bird up on my bike |
#17
Posted to uk.d-i-y
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Mechanically polishing brass that's pitted?
Vet Tech wrote:
I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Please excuse my ignorance: what causes pitting in brass? |
#18
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Mechanically polishing brass that's pitted?
On 27 May, 03:30, Gib Bogle wrote:
Please excuse my ignorance: what causes pitting in brass? Don't really know, but these are the original bits that have been on the front door since 1928 so maybe chemical corrosion from London pollution? VT |
#19
Posted to uk.d-i-y
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Mechanically polishing brass that's pitted?
On Thu, 27 May 2010 00:55:29 +0100, spamlet wrote:
"Bob Eager" wrote in message ... On Wed, 26 May 2010 13:19:52 -0700, wrote: On 26 May, 20:35, Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Solvol Autosol (from Halfords) and a mop attachment for your drill. Funny you should say that. I just purchased some Solvol Autosol (brought back memories of the late 60s and motorbikes) and I have a Dremel with suitable attachment. For exactly this purpose. I just don't have the circular tuit right now. Not polish: wipes off with paraffin and if you don't oil it you end up having to grind off the marks made next time it rains. I ruined the finish on my Ducatti with the stuff before I realised, and went for anodising and wax instead. I used it on alloy casings. -- Use the BIG mirror service in the UK: http://www.mirrorservice.org *lightning protection* - a w_tom conductor |
#20
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Mechanically polishing brass that's pitted?
On 27 May, 00:40, "spamlet" wrote:
Put a magnet on it first, and feel the weight... * OK, I did the magnet thing and there was no attraction and going by the weight, it feels like solid brass. VT |
#21
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Mechanically polishing brass that's pitted?
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#22
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Mechanically polishing brass that's pitted?
In article
, Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. Soak in artificial (non brewed) vinegar first - that removes the oxidisation which is pretty hard. Makes subsequent polishing easier. -- *When the going gets tough, the tough take a coffee break * Dave Plowman London SW To e-mail, change noise into sound. |
#23
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Mechanically polishing brass that's pitted?
Vet Tech wrote:
On 27 May, 03:30, Gib Bogle wrote: Please excuse my ignorance: what causes pitting in brass? Don't really know, but these are the original bits that have been on the front door since 1928 so maybe chemical corrosion from London pollution? VT salt probably or sweat. |
#24
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Mechanically polishing brass that's pitted?
On 27 May, 07:44, Vet Tech wrote:
OK, I did the magnet thing and there was no attraction and going by the weight, it feels like solid brass. Watch out for brass over diecast zinc too. For Screwfix I either check in the shop first, or I buy just the one of something before buying a batch. They mix solid brass and brass over zinc, yet describe them randomly in the catalogues as "brass", "brassed" and "polished brass finish". Not many castings (like doorknockers) are going to be brass on steel, i.e. magnetic. That's more likely for things that are pressed from sheet, such as mirror plates and lock escutcheons. |
#25
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Mechanically polishing brass that's pitted?
On 27 May, 01:00, "spamlet" wrote:
All seconded, save the lacquer bit: always looks better polished and wiped over regularly with oily rag. *Or you'll be repeating the whole process again before long. What's the practical likelihood of that happening on a door knocker? Perhaps your household is better run than my own, but I'm afraid we have such terrible trouble in finding parlourmaids these days there's no likelihood they'll be able to polish the brassware and starch the antimacassars before tea. |
#26
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Mechanically polishing brass that's pitted?
Owain wrote:
On 27 May, 11:29, Andy Dingley wrote: All seconded, save the lacquer bit: always looks better polished and wiped over regularly with oily rag. Or you'll be repeating the whole process again before long. What's the practical likelihood of that happening on a door knocker? Well, if you leave the oily rag in a tin next to the bin, you get into the routine of doing the knockers weekly when putting the bin out. Perhaps your household is better run than my own, but I'm afraid we have such terrible trouble in finding parlourmaids these days there's no likelihood they'll be able to polish the brassware and starch the antimacassars before tea. That's because the parlourmaid classes are too busy getting their tits out for Page 3. No, they are all vying for labours deputy prime minister position. No better than they should be. Owain |
#27
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Mechanically polishing brass that's pitted?
On Thu, 27 May 2010 05:30:15 -0700, Owain wrote:
On 27 May, 11:29, Andy Dingley wrote: All seconded, save the lacquer bit: always looks better polished and wiped over regularly with oily rag. Â*Or you'll be repeating the whole process again before long. What's the practical likelihood of that happening on a door knocker? Well, if you leave the oily rag in a tin next to the bin, you get into the routine of doing the knockers weekly when putting the bin out. Perhaps your household is better run than my own, but I'm afraid we have such terrible trouble in finding parlourmaids these days there's no likelihood they'll be able to polish the brassware and starch the antimacassars before tea. That's because the parlourmaid classes are too busy getting their tits out for Page 3. But who oils their knockers...? -- Use the BIG mirror service in the UK: http://www.mirrorservice.org *lightning protection* - a w_tom conductor |
#28
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Mechanically polishing brass that's pitted?
"Bob Eager" wrote in message ... On Thu, 27 May 2010 00:55:29 +0100, spamlet wrote: "Bob Eager" wrote in message ... On Wed, 26 May 2010 13:19:52 -0700, wrote: On 26 May, 20:35, Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Solvol Autosol (from Halfords) and a mop attachment for your drill. Funny you should say that. I just purchased some Solvol Autosol (brought back memories of the late 60s and motorbikes) and I have a Dremel with suitable attachment. For exactly this purpose. I just don't have the circular tuit right now. Not polish: wipes off with paraffin and if you don't oil it you end up having to grind off the marks made next time it rains. I ruined the finish on my Ducatti with the stuff before I realised, and went for anodising and wax instead. I used it on alloy casings. -- So did I, and then it rained and I ended up having to sand off the rain spots and start again. An oil film is better than a fake shine. Once you take the oxide film off ally, anything can happen. S |
#29
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Mechanically polishing brass that's pitted?
"Andy Dingley" wrote in message ... On 27 May, 01:00, "spamlet" wrote: All seconded, save the lacquer bit: always looks better polished and wiped over regularly with oily rag. Or you'll be repeating the whole process again before long. What's the practical likelihood of that happening on a door knocker? Perhaps your household is better run than my own, but I'm afraid we have such terrible trouble in finding parlourmaids these days there's no likelihood they'll be able to polish the brassware and starch the antimacassars before tea. Dealing with dirty, crazed, lacquer, which has caused pitting where the air and crud has gone down the cracks, is a lot harder than a regular once over with an oily rag. Your choice. S |
#30
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Mechanically polishing brass that's pitted?
On 27/05/2010 00:40, spamlet wrote:
snip Put a magnet on it first, and feel the weight... Lots of 'brass' these days turns out to be plate when you get it (Screwfix for example did solid brass electric sockets for a while, but continued advertising them as the same when they were made of plate.). The pits are often holes that go down to the iron underneath on old stuff, and, on new stuff ally, and you don't want to rub the plate away getting down to the bottom of the pit. Assuming it is solid brass then you may first need to go over it with nitromors as it is often lacquered, and even if it isn't this will get off the ground in skin and grease too. If you do adopt chemical or heat methods watch out for the core metal of some of the old knobs: I got a shock when the grey metal (presumably zinc/magnesium) that took the square turning rod of one of mine melted and ran out - took a lot of fiddling to make a replacement - when I was trying to hurry old lacquer off... Then as TNP says, there really isn't much option but to choose the minimum grade of emery/wet or dry, that will enable you to rub down past the pits. Deep ones you may even have to start off with riffler files. Keep the scratches all going the same way with the first grade, then rub these scratches away by going at right angles with the next grade down; then at right angles again, and so down through the grades. When you have got down to 600 or 1200 - 1400 - depending on how much of a perfectionist you are - T-cut or similar metal polish in a circular motion will rub out the fine scratches that are left. If your pieces are easily detachable you may find it easier to polish with wet and dry under the tap with a dash of wash-up liquid now and again. In preparing metals for microscopic examination a polishing sloping surface with water running over several grades of wet or dry was used, followed by a final burnish on a diamond lapping wheel. Brasso and Autosolve and similar products don't really polish: they just fill in the finer scratches: which you can prove for yourself by wiping a so 'polished' surface with paraffin, which wipes the 'shine' back off. It is better to polish properly - by reducing scratches to the minimum acceptable size - and then oil your product, rather than go for a brilliant finish that will mark and pit after the first fingerprint or raindrop. For a real brilliant finish you will need a proper polishing mop or buffing wheel, for which you can get several grades of cutting 'soap' and jewellers rouge. But it would still be best to wipe the surface with an oily rag regularly afterwards. (Oh and it'll get v hot on a buffer so leather gloves are in order.) The irregular shape of your knocker would probably be best tackled with various grades of brass brush wheel, but you will need (as with the buffing wheels) to find a way to clamp your drill securely, or get a bench grinder/buffer - which is always worth having. Once you have cleaned it with the brush wheel, then you go on to the polishing soaps on the buffing wheel again. Keep different mops for different grades of buffing soap. *Don't* whatever you do, be tempted to use an iron brush wheel. If you don't want to tackle the mops and such, you can achieve a fair bit on irregular surfaces with, say, strips of towelling or bootlaces. and various grades of grinding paste. Hold the knocker in soft vice jaws and work the strips of cloth 'shoe shine boy fashion' through it with one end in each hand: you may actually find this easier than a pukka buffer in fact. Sounds hard, but it is actually satisfying producing a good polish: rather like getting that perfect sharp edge on a chisel or scythe. S Excellent, thanks for that. Just did 6 door handles and the letter box surround. I've tried on a number of occasions over the past 5 or 6 years with Brasso/similar, and never got anywhere. Nitromors didn't *seem* to do a great deal except degrease. I used one of those decorator's sanding sponge things for awkward corners. I'm going with your oily rag maintain sheen method. Rob |
#31
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Mechanically polishing brass that's pitted?
"Gib Bogle" wrote in message ... Vet Tech wrote: I've got items of door furniture (letter box, knocker etc) that are made of solid brass but they've not been polished for years so they're pitted and looking very tired. I've tried Brasso and lots of elbow grease but I'm just not getting down to a level where it would make a difference. So I'm looking for the best way to get them all buffed up by using something that I can attached to my drill. Any guidance would be much appreciated. VT Please excuse my ignorance: what causes pitting in brass? Never really looked at brass, but with the right etching solution on a properly polished and clean metal surface you can see the crystal structure. Most people don't realise that metals are crystalline. (I was jealous of a metallurgist I knew who could bring up the crystals in mag alloy beautifully, but I never could get the etchant right.) The point being that alloys are complex materials made even more complex by impurities, bubbles, and the like. Each of these, and the surfaces and edges of the crystals will have different reactivities. Then there is the electrochemical environment to consider: what other metals are coming into contact, and is there an electrochemical potential difference between them? Then there is the acid in sweat; differences between people and the things they put on their hands. And the air and rain quality and many times so on. The problem is made worse by attempts to preserve the surface with lacquers or varnish. Even if they do not crack, they are still too thin to keep the air out forever, and the metal underneath gradually dulls. Once they craze or chip the metal in the chip or craze, is preferentially attacked and pitted, and then the corrosion spreads under the lacquer. And that's before we think of all the damage we do with our keys, rings etc. This is why you usually see museum staff handling things with disposable cotton gloves. And also why a lot of conservation effort goes into undoing the damage done by earlier attempts at conservation... S |
#32
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Mechanically polishing brass that's pitted?
"Rob" wrote in message ... On 27/05/2010 00:40, spamlet wrote: snip Put a magnet on it first, and feel the weight... Lots of 'brass' these days turns out to be plate when you get it (Screwfix for example did solid brass electric sockets for a while, but continued advertising them as the same when they were made of plate.). The pits are often holes that go down to the iron underneath on old stuff, and, on new stuff ally, and you don't want to rub the plate away getting down to the bottom of the pit. Assuming it is solid brass then you may first need to go over it with nitromors as it is often lacquered, and even if it isn't this will get off the ground in skin and grease too. If you do adopt chemical or heat methods watch out for the core metal of some of the old knobs: I got a shock when the grey metal (presumably zinc/magnesium) that took the square turning rod of one of mine melted and ran out - took a lot of fiddling to make a replacement - when I was trying to hurry old lacquer off... Then as TNP says, there really isn't much option but to choose the minimum grade of emery/wet or dry, that will enable you to rub down past the pits. Deep ones you may even have to start off with riffler files. Keep the scratches all going the same way with the first grade, then rub these scratches away by going at right angles with the next grade down; then at right angles again, and so down through the grades. When you have got down to 600 or 1200 - 1400 - depending on how much of a perfectionist you are - T-cut or similar metal polish in a circular motion will rub out the fine scratches that are left. If your pieces are easily detachable you may find it easier to polish with wet and dry under the tap with a dash of wash-up liquid now and again. In preparing metals for microscopic examination a polishing sloping surface with water running over several grades of wet or dry was used, followed by a final burnish on a diamond lapping wheel. Brasso and Autosolve and similar products don't really polish: they just fill in the finer scratches: which you can prove for yourself by wiping a so 'polished' surface with paraffin, which wipes the 'shine' back off. It is better to polish properly - by reducing scratches to the minimum acceptable size - and then oil your product, rather than go for a brilliant finish that will mark and pit after the first fingerprint or raindrop. For a real brilliant finish you will need a proper polishing mop or buffing wheel, for which you can get several grades of cutting 'soap' and jewellers rouge. But it would still be best to wipe the surface with an oily rag regularly afterwards. (Oh and it'll get v hot on a buffer so leather gloves are in order.) The irregular shape of your knocker would probably be best tackled with various grades of brass brush wheel, but you will need (as with the buffing wheels) to find a way to clamp your drill securely, or get a bench grinder/buffer - which is always worth having. Once you have cleaned it with the brush wheel, then you go on to the polishing soaps on the buffing wheel again. Keep different mops for different grades of buffing soap. *Don't* whatever you do, be tempted to use an iron brush wheel. If you don't want to tackle the mops and such, you can achieve a fair bit on irregular surfaces with, say, strips of towelling or bootlaces. and various grades of grinding paste. Hold the knocker in soft vice jaws and work the strips of cloth 'shoe shine boy fashion' through it with one end in each hand: you may actually find this easier than a pukka buffer in fact. Sounds hard, but it is actually satisfying producing a good polish: rather like getting that perfect sharp edge on a chisel or scythe. S Excellent, thanks for that. Just did 6 door handles and the letter box surround. I've tried on a number of occasions over the past 5 or 6 years with Brasso/similar, and never got anywhere. Nitromors didn't *seem* to do a great deal except degrease. I used one of those decorator's sanding sponge things for awkward corners. I'm going with your oily rag maintain sheen method. Rob Glad of the feedback. If you were able to polish it without too much swearing, the lacquer was probably mostly gone or wasn't there in the first place, but it is always worth doing as even with Nitromors, some of the finishes take some time to wrinkle up: and as you say, it degreases and brightens a bit even if there is no actual lacquer left. Now you have it properly cleaned and polished you can give it an occasional Brasso to remove any slight dullness (You can do similar with white spirit and ammonia on cotton wool), but still go over it with the oily rag after. I just keep a cotton cloth with 3 In One oil on it, in a plastic bag with the dusters. Cheers, S |
#33
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Mechanically polishing brass that's pitted?
In message , Gib Bogle
writes geoff wrote: Funny you should say that. I just purchased some Solvol Autosol (brought back memories of the late 60s and motorbikes) And, by coincidence, I've just found half a tube of it which must be what, 30+ years old Those were the days eh? As long as you had a tube of solvosol, grease and hermatite, what more did you need ? If there's one thing that I like It's a burn up on my bike A burn up with bird up on my bike So - solvosol, grease, hermatite and KY then ... -- geoff |
#34
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Mechanically polishing brass that's pitted?
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Gib Bogle saying something like: Please excuse my ignorance: what causes pitting in brass? Carbonic acid in the rain, impurities in the brass, forming simple cells of reaction. |
#35
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Mechanically polishing brass that's pitted?
On 27 May, 03:30, Gib Bogle wrote:
Please excuse my ignorance: what causes pitting in brass? Not much. Brass is usually failrly resistant to such attacks. it will discolour readily, but not pit as such. If it does start to corrode to the level of pitting, it's usually (depending on alloy) by dezincification. This is a corrosion of the more reactive zinc part of the alloy, leaving excess copper behind. It forms large pink areas. Pitting in "brass" is usually most serious because it's an indication that the "brass" wasn't brass in the first place, but was a relatively inert plating of brass over a reactive diecast zinc body. Pitting is caused when the plating is perforated and the zinc underneath starts to react (which it will do, with almost anything). The pitt can be hiding a more serious hole beneath, and polsihign it just strips away even more of the plating. |
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