Colour of ignition spark question

[Spitty]

I have heard arguments both ways. Some will argue that an Orange spark is weaker than a blue spark. Others may argue that the spar colour is no real indication of the power behind that spark.
I am not really interested in hearsay arguments but I am asking if anybody has a definitive 'Scientific' answer.

 

[Exhaustgases]

It will depend on what deposits exist too.

 

[Lubener]

I have heard arguments both ways. Some will argue that an Orange spark is weaker than a blue spark. Others may argue that the spar colour is no real indication of the power behind that spark.
I am not really interested in hearsay arguments but I am asking if anybody has a definitive 'Scientific' answer.

The color isn't as important as the ability of the spark to jump across the plug's gap. If a spark can jump atleast a 1/4 inch gap, it's fine. That was quoted by Nicola Tesla over a couple beers. Is that scientific enough?

 

[Spitty]

Personally I agree with the comments made, but I am hoping to setting a long running argument with a friend that has a difference of opinion.
I would not consider an ignition spark to be good or bad based solely on the colour or if it looks 'Fat' or not, but would measure how har the spark can be made to jump in atmospheric pressure.

 

[paulo57509]

My father had one of these on the bench in his shop. The oscilloscope made these essentially obsolete, along with rising labor costs.

You could test a "bad" spark plug at 1-atm and it would spark. Add compressed air to simulate compression and the spark would be absent.

 

[meep]

I’ve never seen anything like that….

from some random search, it seems that color has very little to do with power:
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The actual color of the sparks or arc in air depends on the current and degree that electrode material is vaporized. Low-current sparks or arcs are typically blue-purple primarily from ionized nitrogen and oxygen in the atmosphere. High-current sparks and arcs are mostly bluish-white due to the higher temperatures inside the discharge. In addition, evaporation of the conductors (or coatings on the conductors) may also color the sparks. And, the color of ejected droplets of molten (and often burning) metal also reflect the elements in the conductors, especially if the metals are easily oxidized.

For example, sparks between aluminum, magnesium, or titanium conductors are often intensely white, as are ejected and burning droplets. An arc between carbon or tungsten electrodes is also brilliant blue-white with little ejection of solid or liquid material. An arc between copper conductors is often a greenish color due to excited copper ions in the arc plasma. Greenish power arcs are often seen during electrical utility faults in transformers, between copper bus bars, or older copper wires/cables. Sparks between steel or iron electrodes are usually blue-white, accompanied by yellowish-white droplets of burning metal. Sparks or arcs between noble metals (such as gold or platinum) are typically white or blue-white while the droplets are yellow-white, rapidly cooling as they travel through the air without oxidizing.
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-m