Whiting is finely ground chalk that is used as a pigment in paints and in papermaking. It is practically pure calcium carbonate. It is a fine white powder.

For information chalk used on blackboards is not calcium carbonate but calcium sulphate so do norrt be tempted to grind up these.

Whiting in methylated spirit is a mild abrasive that may be used to clean silver or to prepare glass for gilding. In this case however could the whiting be there simply to protect the piston rings from corrosion until the engine is completed?

Brian G

I never bother to coat my rings with anything but as Rod says Tippex would stop oxidation though you will then have to clean off the remains of it.

As a child I remember plimsolls (remember them?) being smartened up by whitening them.

If the whitening is calcium carbonate and its heated to 'cherry red' it will turn into calcium oxide. Isn't this a bit caustic to touch ?

Not at that temperature. Around 900 degrees Celsius is required to decompose Calcium carbonate. I believe the reaction proceeds quite quickly at 920-930 degrees (the temperature in a the last of a 4 stage preheater – in a dry process cement kiln).

Rings only need to be heated until they relax, then cooled. The new ‘set’ of the ring can be repeated to a larger ‘set’ if required. For rings I have ‘set’, the ring was expanded to the required size and then heated until it fell off the expander. They were rather larger rings than the average model steam engine, I expect.

I had no idea of the actual temperature but if it is around 500 Celsius, that would be classed as dull-red, I would think. Well, dull-red to most – I can’t easily see it glowing until it gets really hot – being red-green colourblind.🙂

As Fowlers Fury says cherry red is too hot for this sort of thing leading to unwanted metallurgical changes.

Especially as most folks idea of cherry red is more like the "fake" dyed, flavoured and candied glace cherries wot mum used to put in cakes or on top of the icing. Toned down a bit in recent years but back in the day these were just short of Dayglo!

By colour 480 – 520 °C is when the barest hint of red appears in a dark environment. Odds are you will be high when going by colour but, probably not too high.

Clive

Emgee,

Thanks for posting that link, I had not seen it before and found it very informative about issues beyond piston rings.

Rod

Another (prettier) version of Howell's article: **LINK**

'The Trimble method' gets bandied about quite a lot, particularly in the USA. Prof. Chaddock (Loughborough, England) described 'the method' in 1967, long before Trimble's article in Strictly IC – in the '80, IIRC. It's difficult to believe that Trimble was unaware of Chaddock's writings, but his article made no reference to what had gone before. Let's give credit where credit's due – it's 'the Chaddock method'. Of course, Trimble was an American…

Hi Kiwi Bloke

I thought the Chaddock method called for the ring to be turned a few thou over bore size but the Trimble method calls for a ring turned to the bore diameter.

Clearly Prof Chaddock was the first to publish a method as far as I know without research, but if the pages of ME's are searched I believe there may be others detailing a method before either Trimble or Chaddock, 1 candidate would be a Mr B Stalham of Kings Lynn whose air cooled vee twin model hydroplane engine appeared on the cover of the ME from memory during the 1950's.

Like many parts there is always a different method of producing it, best to use what suits you.

Emgee

1954    111    2782    341    B.Stalham    A Supercharged Vee Twin. Details of an Experimental 15 cc Engine for a Racing Hydroplane

name changed

Edited By Emgee on 07/10/2020 22:55:49

Edited By Emgee on 07/10/2020 23:00:15

Yes no doubt Trimble was aware of the earlier work done by Prof Chaddock, perhaps that's the reason he suggests turning the rings OD to bore diameter, if scaling can be prevented it is less work than finishing the rings to diameter after slitting/breaking and heat treatment, also any minimal out of round shape will be so small that when fitted to the cylinder it will not be detrimental to the engine performance when bedded in.

Emgee