Double anodizing?

[John Stevenson]

Just spent an hour looking thru old posts in search but couldn't find anything to suit so here goes.

I want to do some small signs that have a lot of detail on them, they are actually charts off old machine tools. The originals looked to be etched on bras plate but so far the results we have got back from 2 people are not up to scratch.

The background is in relief and black and the letters are polished brass. I can do these on the laser from the various plastics out there but it scratches bad and a clear cover isn't acceptable.

So after the run down I wondered if I got some gold anodised sheet which is easily available over here [ UK ] burnt the relief off and then sent the plate out for anodising again but in black this time, would it work ?
As I say there is some fine detail on these plates, some of the text is only 1/16" high.

Thanks in advance for any insight.

[Ross Moshinsky]

You're making this way too complicated. Black brass or black steel is what you want. You should be able to buy it from any trophy supplier or trophy shop.

[dave standing]

Having spent 25 years in the anodising game, I don't think you will be able to anodise a second time using a black dye without destroying the initial anodised film containing the gold dye.

[Dave Sheldrake]

nope, won't work unless you relief anodise and even that is hit and miss :( ^^^^^ Dave above with 25 years in says no then it's pretty fair bet it's no :)

[Michael Hunter]

Not sure about blackening on gold anodised, but it does work OK the other way round.

I've engraved black anodised (using the minimum power necessary to get rid of the black), coloured the engraved part with spirit-based felt-tip pens and then sealed it by putting it in boiling water for 10 mins.
After the boiling, the colouring in the engraved part won't wash off with solvents.


In theory it should work with dark colours on light anodising too, but unless the original anodising was absolutely perfect, then the dark colour will probably get into the background as well as where it was actually wanted.

[Scott Hearn]

The anodize that is there will need to be etched off, the whole thing re-anodized (the coating that's on it isn't conductive). It's possible to silk screen the pattern on before sealing but I think it's just not practical and will be cost prohibitive unless you are going to be doing large quantities.

Did a few years in an aerospace metal finishing shop where anodize was the main finish.

[AL Ursich]

Would Graveoxide work on the exposed area?

http://www.gravograph.us/engraving-products/Engravers_Supplies.php

[Kev Williams]

I'm with Ross on this one, why not use one of the various laserable trophy metals?

I'm curious about your reason for not using plastics because "it scratches bad"-- trophy metals, actual brass, stainless steel, any of these are easily scratched too. Any of these can be clearcoated with clear enamel with great results...

Have you considered laserable reverse engravable acrylic? IPI (and others I suppose) have R-E plastics-- I use IPI's... Comes with either a glossy or matte finish. Glossy will look great, but- can scratch easily. Matte finish is non-glare, and much more resistant to scratches, but mutes the colors a bit. The back side has a 'main' color layer and a white coating that you laser thru in reverse. You'd want the black, and a can of metallic gold spray paint. just engrave the back in reverse (tip: DO make a second cleanup pass), mask off the plate around the engraving, then hit the engraving with the gold paint...

[John Stevenson]

Thanks lads, that's what's nice about this forum is the sensible answers you get.
Replies in no order.

Not being in the engraving business full time, this is just a side line to a repair business I don't have the experience you guys have, hence the questions.

Next question is laserable trophy metals. I usually deal with 908 ltd in the UK for the material I buy and cannot see black brass, A Google search found loads of hits but all from companies who wanted to do my trophy for me, not sell me sheet material.

So next question is any links please for suppliers in the UK and any examples etc to see just what this material in.

Thanks.

[Ross Moshinsky]

I have no idea who supplies materials in the UK. I'm sure someone from over there could help you.

If you're in a pinch, you should literally be able to walk into any trophy/awards shop and ask them for black "brass". The reason I call it "brass" is because it's less and less common people actually use brass. For example, we use either brass plated steel or brass plated aluminum. Brass is ~3x the cost of steel or aluminum and offers no real benefits when being laser engraved.

[vic casware]

Pretty sure Suregrave (trotec) in the Uk have Black Enameled Brass

[John Stevenson]

Many thanks guys, some good leads there.
On the Suregrave site they referenced some Aluminium blacking liquid and some brass so wondered about doing the gold anodised material [ of which I have plenty ] and then blacking it?

Unfortunately the Suregrave site is one where you have to ring for every price ? So a quick search on blacking fluid found another UK site, with prices , long, short is I have ordered some blacking fluid and some black brass to have a play with.

So next week when it's all got here I'll see how it all works out. Biggest worry is these plate unlike plaques on trophy's are in a high work area. They are on flat surfaces on machine tools where people stack spanners, tools and chuck keys etc. This is one reason i didn't want to use the metallised plastic as some I have tried just get scratched up beyound use very early on.

I'll report back later.

[matthew knott]

the Aluminium blacking fluid only works on bear aluminium, you might be able to remove the anodize layer with your laser but normally a co2 only bleaches the colour out, Guess using high power and going slow might work for you, when you use the fluid it needs to be applied with a bit of agitation, it works fairly quickly straight away or not at all so you will know quickly if its working. The black if you get it scratches very easily, as i suspect will the gold. Blacked brass will also be incredibly easy to scratch, without thick clear coat these wont last 5 minutes in a harsh environment.
I think i know the think you trying to make, they used to be chemically etched then filled with paint, what size are the plates going to be?

[John Stevenson]

Matthew, about 2" by 4.5" which makes the text very small. They can't be larger as they sit in a cast pocket on top of the gearbox.

Anyway an update now I have the blacking fluid and the black brass.
Blacking fluid will not work on lasered anodised gold aluminium as Matthew said, it just does nothing a bit quite wipe on a bit of bare alloy and it marks fine so that is a bit more experiance. Still need to try the black brass but after seeing it I know it will scratch bad.

Long short I'm going to have to go the original route and etch these but thanks for all the info, that black brass which I didn't know about will do for some other jobs.

[matthew knott]

I could laser them into normal brass, we have a new 60 watt fiber laser that's good for brass. You could etch them yourself I guess