# Engineer's Blue vs. Engineer's Orange



## Jelly (22 Nov 2015)

So I bought a big 5Lt container of marking/layout fluid (essentially a fancy modern version of engineers blue) from my local engineering supplier, last one in stock so they cut me a good deal as "It's been here quite a while, you'll need to mix it with a stick then shake it for 20mins before it's usable". 
They and I both thought it was blue from the packaging, but in fact it's the orange version usually used for contrast when scraping/filing, something I only discovered this today whilst working on my gift for the SS.

My question is, does the blue give that much of an advantage over the bright coloured versions when used for layout, specifically enough to spend more money on?

I can see the layout lines I'm scribing clear enough by virtue of shiny metal lines in non-refective orange, but there's not a great amount of contrast, I'd say it was "workable"... Am I expecting too much, or indeed should I just have shaken it for longer?


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## chaoticbob (23 Nov 2015)

Jelly":15jlpbaf said:


> I can see the layout lines I'm scribing clear enough by virtue of shiny metal lines in non-refective orange



Erm - if you can see the layout lines clearly, why worry further?
Robin


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## Jelly (23 Nov 2015)

chaoticbob":1ynlp2k5 said:


> Jelly":1ynlp2k5 said:
> 
> 
> > I can see the layout lines I'm scribing clear enough by virtue of shiny metal lines in non-refective orange
> ...



Oops sorry I didn't make it clear above, I can only see the reflectivity of the scribe, whilst the bench I'm laying out on is pretty well lit thats fine, but the milling machine and other metalworking tools are in a much dimmer light (will get sorted eventually) so I'm not so sure the layout will be so visible...


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## Wildman (23 Nov 2015)

5ltrs?????? that will last you and your descendants 100 years, hee hee


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## Jelly (23 Nov 2015)

Wildman":x6wsbmla said:


> 5ltrs?????? that will last you and your descendants 100 years, hee hee



That became readily apparent when I first applied it... If anyone wants some I can probably spare a few small bottles.


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## Cheshirechappie (23 Nov 2015)

There's an old machinist's trick that might help a bit. Mark out for machining, but before putting the component on the mill, use a small dot-punch and hammer to place some pop-marks on the scribed line. The punch should ideally be quite sharp-pointed (certainly more so than a regular centre punch) and the marks need not be large, certainly not huge craters. The sharpish punch can be 'felt into' the scribe lines, so can be placed very accurately. The idea is that as the swarf and coolant wash off the marking fluid and the scribe line becomes well-nigh impossible to see, the witness punch marks remain visible. Once the machining cuts the dot-marks neatly in half, you're there. Some people leave about three-quarters of the mark still visible, giving themselves a bit for final hand-fitting and finishing. How many dots? Use applied common sense, but about one every half-inch works well for me on small jobs.

Fabricators (well, some of them!) use the same technique when marking out plate or sections for cutting freehand with a burning torch. In that case, rather heavier punch-marks are in order, about one per inch; cutting then becomes a matter of joining the dots, with due allowance made for the cut width and cleaning up.

This trick isn't seen so much these days, especially in mills with a DRO fitted. In that case, once a datum is established between cutter and job, all dimensions can be read off the DRO screen. Similar can be worked on a manual machine with graduated dials on the feedscrews, but in practice it's not easy because keeping track of the number of turns of the handwheel is almost impossible unless you're very disciplined about noting every turn on a jotter or whatever.


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## Limey Lurker (23 Nov 2015)

I think that you are confused between Engineer's Orange (a non-drying ink used for checking high spots on surfaces) and Marking-Out Blue, a fast-drying paint, impervious to machining coolants, used for, well, marking-out!


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