Do weights get weightier?

[benhall.1]

It being the time of year, I've been measuring out my fruit for my Christmas Cake this afternoon. Being of a philosophical bent (steady) I started thinking about the weights. I don't know about anyone else, but it's almost a point of principle that I never wash or clean the weights for my scales. I like the look of them, slightly dusty, with bits of flour on them and so on ...

... which led me to think "If I go on like this, even if no more flour gets stuck on them, they'll still accumulate stuff - bits of skin and oil from my hands, general detritus from kitchen preparations and stuff flying about the kitchen from frantic cake-making activities ..."

So my questions are:

* Will my weights get gradually heavier the longer I own them?
* At what point will they be so inaccurate that my recipes won't work any more?
* Assuming that they are getting heavier over time, will it matter, so long as they get heavier in proportion with each other?
* If my weights keep getting accretions of skin, at what point will they be more human than weight? (I may not have been the originator of this thought. I think that maybe it came out of something called The Third Cake, by someone with the appropriate name of "Flan".)
* Will my cake be moist yet firm, supple yet fresh, intoxicating in its ...

[wibble]

[mutepointe]

Roaches and other small life forms may help keep the debris to a minimum or at the very least prevent critical mass. You'd have to work mightly hard to achieve critical mass. Even that should be short-term.

[david_h]

* At what point will they be so inaccurate that my recipes won't work any more?
* Assuming that they are getting heavier over time, will it matter, so long as they get heavier in proportion with each other?

If the layer of extra material is roughly the same thickness the smaller ones will get proportionally heavier (added weight proportional to surface area, original weight to the volume). As for the recipe as a whole, what state are the things you measure volumes in ?

There is a lady who has a 'stall' at our local food fair on behalf of the local council. Her 'props' involve a fridge and microwave with sticky stuff on the insides. She would a have thing or two to say about your weights. She is not from the weights and measures department.

[chas]

Just because I'm a geek, I ran some numbers. I assume your weights are cylindrical and about half again as tall as they are in diameter and made from brass, and that the layer that's growing on them has a density of 1 g/cc. If the layer is 0.1 mm thick, the error goes from 0.6% for a 10 g weight to 0.1% for a 1 kg weight. If the layer is 1 mm thick, the errors are 6 % for a 10g weight to 1 % for a 1 kg weight. The latter seems potentially significant, not so much for things like salt and spices, but for leavening, which is probably in the few g range. OTOH, 1 mm of shmutz on the weights seems kinda gross, and there is potentially some wear of the weights due to acid in sweat. (An aside: the US, and I think most of the world, still rely on artifacts for the standard kilogram. The US weight is a ball of, I think, platinum-iridium that was made a little over 100 years ago. It's estimated that it's lost 60-70 micrograms of mass through evaporation since it was made.)

Your local metrologist,

[benhall.1]

Some lovely, thoughtful, replies so far, which give one further food for thought (as it were).

Chas, I think we need to go into your reasoning in a bit more depth. Is there a way of predicting the rate of accretion as compared with the rate of loss of mass due to friction in use, acid erosion and evaporation? Not to mention predation of the accumulations (if I may use that phrase in relation to matter which is, I trust, inanimate) by the small fauna inhabiting my kitchen? Come to think about it, would moulds and fungi have a part to play as well?

Given these various counter posed forces, some tending to increase the mass of the weights whilst others tend to reduce mass, would there be a point at which equilibrium would occur, and those forces would exactly balance out? If so, could we predict when that would be?



(I'm really looking forward to my cake. Yummm! )

[Innocent Bystander]

When I were a lad studying Chemistry, and weighing out mysterious powders on a beam balance, we were instructed to use tweezers to lift the weights, otherwise the friction of our fingertips would abrade the weights and reduce their accuracy. They may have been concerned about the natural grease on fingertips, as well as the other sticky substances on schoolboys' hands, but nobody ever mentioned that.

I put it to you that the persistent abrasion of your fingers and the kitchen surfaces is reducing the mass of your weights, and will affect the situation more than any accretion of lighter material.

[benhall.1]

When I were a lad studying Chemistry, and weighing out mysterious powders on a beam balance, we were instructed to use tweezers to lift the weights, otherwise the friction of our fingertips would abrade the weights and reduce their accuracy. They may have been concerned about the natural grease on fingertips, as well as the other sticky substances on schoolboys' hands, but nobody ever mentioned that.

I put it to you that the persistent abrasion of your fingers and the kitchen surfaces is reducing the mass of your weights, and will affect the situation more than any accretion of lighter material.

Yes, I had considered that. I'm really not sure the comparison works, though. In the chemistry lab, there wouldn't be nearly as much mass tending to accrue to the weights as there is in my kitchen (or any kitchen). Especially when I'm making cake.

I still reckon that the two opposing forces are indeed at work, but that there's a greater accretion of additional mass than there is erosion - at least in the relatively early days of the weights.

I guess I could measure the tendency for weights to lose mass. Old sets of weights are reasonably common in antiques shops. If I bought an old set, I could measure, at least for them, the lost mass by reference to my own weights. Of course, then, environmental factors would come into play. Where were they used during their active life? What conditions were they operating in? Etc Etc

[I.D.10-t]

Next thing you'll be asking is how to determine the moisture content of the flour to adjust the weight for pure flour content.

I have a feeling that I am one of those cooks that would drive you crazy with my lack of precision. I have been known to use a tea cup to measure out 1C of flour and an actual teaspoon to measure out baking powder. If the recipie asks for one and a half cups, I'll eyeball a half cup for the second scoop. A splash of milk or a touch of flour to get the right consistency and into the oven it goes. Normally I spend a lot of time in R&D to get the recipe just right, type it out onto a 3X5 card, and then never completely follow my own recipe ever again.

[Innocent Bystander]

Yeah, Ben. Tools, not rules!

[Pfreddee]

Some items, such as photography equipment, do vary in weight. For instance, I own a Bogen Variable-Weight tripod with a three-way pan head. It is the Variable-Weight model because the farther you carry it, the heavier it gets...

[mutepointe]

Just to stir the pot a bit. I think altitude may have more of an effect on your baking than the accuracy of the weights. Recipes are often adjusted for higher altitudes but the recipes don't mention reductions or additions because your position is less than the highest altitude. What if you were baking on a Zeppelin?

Bonus Question. How would using those weights affect a recipe if a person was baking on the moon?

[benhall.1]

Next thing you'll be asking is how to determine the moisture content of the flour to adjust the weight for pure flour content.

I have a feeling that I am one of those cooks that would drive you crazy with my lack of precision. I have been known to use a tea cup to measure out 1C of flour and an actual teaspoon to measure out baking powder. If the recipe asks for one and a half cups, I'll eyeball a half cup for the second scoop. A splash of milk or a touch of flour to get the right consistency and into the oven it goes. Normally I spend a lot of time in R&D to get the recipe just right, type it out onto a 3X5 card, and then never completely follow my own recipe ever again.

Yeah, Ben. Tools, not rules!

Well, it depends what I'm cooking. If I'm making pastry or baking a cake, then I weigh very carefully indeed. If I'm cooking up a chicken casserole, maybe with some tomatoes, peppers and chillis, then everything is done by eye/guesswork. And that includes any cornflour, for instance, that I may put in to thicken the sauce.

Baking on the moon! Mmmm ...

"Giant scones are what we bake
Baking on the moon
I hope the eggs will break
Baking on the moon

Some may say
I'm baking my life away
No whey ..."

[chas]

Just to stir the pot a bit. I think altitude may have more of an effect on your baking than the accuracy of the weights. Recipes are often adjusted for higher altitudes but the recipes don't mention reductions or additions because your position is less than the highest altitude. What if you were baking on a Zeppelin?

Bonus Question. How would using those weights affect a recipe if a person was baking on the moon?

Based on Ben's original question, he is using a balance rather than a scale, so gravity wouldn't affect the amount measured out. The real issue with the moon is pressure, which is really what your first question is about. It's high altitude taken to the extreme. The biggest effect would be that all the liquid ingredients would boil off. No amount of baking soda will help that.

[david_h]

How do you know the weights were right in the first place ? Some weights you find in second hand shops have a recess in the base with a lead plug showing some sort of stamp. They come from shops. Every now and then someone from the council - not the one mentioned above, this time from weights and measures (are they called trading standards now ?) - would come round and check them. The stamp in the lead was a 'passed' mark. I was told that they were calibrated from new by scraping off some lead or hammering in a bit more to bring the weight right.

Without that stamp how do you know you have been doing your recipes right ?

(I always worried about scraping metal off those laboratory weights with the tweezers)

[benhall.1]

Ooh! I don't think I've got any weights with the lead plug or the stamp. Sounds cool.

In the meantime, if my weights were never accurate, how come my cakes taste so good?