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Black aluminium


Fishman
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I was thinking of buying an aluminium ABM bridge in black and the company tell me that black aluminium is no longer available as aluminium isn't great for paint adhesion

It seems doable as other brands offer this combination

Any thoughts on this?

Edited by Fishman
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Just now, TheGreek said:

@Bassman666 had the hardware on his Lakland blacked - might be an idea to PM him...

Thanks @TheGreek – the ABM isn't in stock until late January – the bridge is for the Wal Pro 1e rescue that @Andyjr1515 is working on for me – not sure I can wait until then so might go with the Hipshot A

Will consult @Bassman666 if the need arises – thanks for the tip 😊

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Anodizing is the best way to get the colour to the Al. But, as the base material itself is soft, the hard coating will be detached if the material is hit. The soft aluminum is not able to support the hard surface. Some aluminum qualities also corrode especially by acids, like sweat.

Aluminum oxide is very hard, by the way. If the colouring is done in a proper way and you treat the unit decently, it may look good for ages. Paints tend to wear quite quickly. The base treatment is demanding, and most of the painted aluminum looks bad sooner or later. Anodizing is simply the best choice.

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On 18/12/2020 at 09:08, itu said:

Anodizing is the best way to get the colour to the Al. But, as the base material itself is soft, the hard coating will be detached if the material is hit. The soft aluminum is not able to support the hard surface. Some aluminum qualities also corrode especially by acids, like sweat.

Aluminum oxide is very hard, by the way. If the colouring is done in a proper way and you treat the unit decently, it may look good for ages. Paints tend to wear quite quickly. The base treatment is demanding, and most of the painted aluminum looks bad sooner or later. Anodizing is simply the best choice.

Chose the right aluminium alloy (7075) and it's harder and stronger than mild steel, even without anodising.

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7 hours ago, Stub Mandrel said:

Chose the right aluminium alloy (7075) and it's harder and stronger than mild steel, even without anodising.

http://www.matweb.com/search/DataSheet.aspx?MatGUID=4f19a42be94546b686bbf43f79c51b7d&ckck=1

Steel is different, usually resilient compared to Al. Different materials, different sets of properties.

Anodized surface does not affect the base material.

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15 hours ago, itu said:

http://www.matweb.com/search/DataSheet.aspx?MatGUID=4f19a42be94546b686bbf43f79c51b7d&ckck=1

Steel is different, usually resilient compared to Al. Different materials, different sets of properties.

Anodized surface does not affect the base material.

Indeed, perhaps I worded it poorly. Many people assume because 'aluminium' is soft aluminium alloys are a poor choice for jobs where toughness is a useful attribute.

I do my own anodising BTW, usually 6082:

145436400_66ED(1).thumb.JPG.79171812854bb79b89e3e25d0f7b7e88.JPG

 

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6 hours ago, itu said:

Wow! What kind of a process you have?

Lots of goggles and double containers...

Clean scrupulously

Strip/degrease in sodium hydroxide - do not touch with fingers after this!

Rinse.

Polish a titanium rod with wet and dry, and clip into or onto the job.

Suspend or put on plastic mesh tray in a container of 13% sulphuric acid (dilute enough to (just) not need a licence.

Connect to +ve of a 4A, 12V transformer via a moving iron (very tough) 5A moving iron meter.

Connect -ve to a big flat lead cathode (I cast my own from lead pipe) placed as far as possible from the item.

Meter hits the stop but in a few seconds usually drops to 4.5A max.

In theory do complex calculations for time and current. In practice and on the advice of an expert, the size of the work tends to determine the current. Most things take 30-40 minutes but for large objects (like the telescope body) wait until the current drops right down away. This will take some experimenting. Move the work at least once (inverting it if possible) to avoid any parts being shielded from the current, make sure the current is still flowing There's some feedback so the current tends to concentrate where the anodising is thinnest.

When looking uniformly grey and current is low, switch off and rinse well in clean water. DO NOT TOUCH!

Now drop into a bath of properly prepared anodising die. This is vastly more repeatable than using other types of die, and is the only element of the process (other than buying titanium rods for connections) where I would advise gritting teeth and paying the price.

Colour should start to take almost instantly, black is fairly quick but some colours take time to develop (e.g. the gold) and this gives time to select colour.

All your fingerprints and machining marks show at this point. Strip in NaOH, polish, and go back to the start. You will learn to be scrupulously clean.

Once you have a good result, boil for 10 minutes in clean water, or put in a suitable sealing solution. Or do both.

 

This uses some really nasty chemicals. I keep sulphuric in a sealed container with a clip on lids (so I don't have to do any pouring) and at all times keep it in a plastic bowl large enough to contain any spill with washing soda loose in it to neutralise any drips. I keep dilute washing soda to neutralise any splashes/drips. The caustic soda (NaOH) doesn't need to be as concentrated but is still potentially nasty.

Wear goggles, wear gloves (blue nitrile gloves are great). Wear clothes that don't matter - any drip  of sulphuric will create a hole unless neutralised straight away. Just be really careful, keep everything at ground level or a clear bench and avoid any trip hazards and think about what you will do if anything goes wrong - especially how to get to a tap fast if you get acid anywhere near your eyes.

Did I say be careful?

It does sound very hit and miss, but I was assured by the chap who sold me the dies (who also runs anodising courses) that 99% of the advice online about exact currents etc. really only matters in a production setting where repeatability is essential. For larger objects just accepting longer times with lower currents is fine, essentially anodising will keep forming whatever the current until you get a good thick layer and then the current will drop and there will then be very little change and it tends to even itself out.

 

 

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