Why has my butter gone cold?

[ProDave]

One of the advantages of a well insulated house that never goes cold overnight when the heating is off, is that the butter in the butter dish in the kitchen remains at a spreadable temperature.

 

Only it has stopped doing that.

 

The reason, is just before Christmas we has the granite worktops fitted in the kitchen.  The butter dish sits on that worktop, and now it's just a little too hard to spread.

 

So I tested the theory and moved the butter dish to the island, which has an oak worktop.  The butter has returned to being spreadable.

 

According to my IR thermometer, both the wooden and stone worktops are sitting at room temperature of 20.5 degrees.

 

If you hold your (warm) hand on the stone worktop it feels cold, but that is because of the higher thermal conductivity compared to wood, so it sucks heat out of your warm hand quicker than the wood does.

 

But the butter is not generating heat.  So how can it be soft when sat on one 20.5 degree worktop, and hard when sat on a different 20.5 degree worktop?

 

The question follows on to SWMBO wants stone shelves when we build the larder to "keep things cool"  I had previously dismissed that as an old wives tale. But now I am not so sure? 

 

P.S.  Leave a cup of tea on the stone worktop and it is cold at the bottom. Again I understand that, the heat from the tea is being conducted away into the room temperature stone.

[joe90]

Like you I thought once the “house and it’s contents “ were up to temp they would (mostly) stay that way. I know my wood stove is below room temp but that,s because it has access to outside temps. @SteamyTea will be along in a mo with a scientific reason (again, something I will have to google to try to understand). My original house plan had a north facing larder with cast concrete or stone shelves.

[SteamyTea]

Or @Ed Davies will explain it with radiation.

Trouble is that it is not a controlled environment.

Was it the same butter, was it the same dimensions, are there any drafts, sunshine hitting it.

I buy Flora as I know it will spread straight from fridge, lasts weeks as well.

Not do good for sauteed mushrooms, but then I don't have them at home much.

[ProDave]

The IR thermometer says the actual butter temperature is also 20.5 degrees.

 

I guess I need to return the butter dish to the stone worktop, wait for temperatures to equalise and re measure the butter temperature.

[Ed Davies]

10 minutes ago, SteamyTea said:

Or @Ed Davies will explain it with radiation.

 

Well, yes, that was the first thing that came into my mind: is the position on the granite worktop closer to a window?

[SteamyTea]

The initial butter temperature will make s difference.

Oddly, I am sitting in the sun reading Randall Munroe's What If?

Write to him and ask, Google xkcd for an email.

[ProDave]

15 minutes ago, Ed Davies said:

 

Well, yes, that was the first thing that came into my mind: is the position on the granite worktop closer to a window?

On the granite worktop it is about a metre from a window.  On the wooden worktop it is about in the middle of the room.

 

But the point is, the butter used to live on a wooden worktop exactly where the granite is now, and it remained spreadable.

 

[Ed Davies]

14 minutes ago, ProDave said:

But the point is, the butter used to live on a wooden worktop exactly where the granite is now, and it remained spreadable.

 

Ah, yes, good point. But maybe the granite is more emissive so a) loses more heat to the window but b) appears slightly warmer to the IR thermometer. Try measuring the surface temperatures with a bit of masking tape or something on them. Once you start measuring closer than about +/- 1 °C the notion of “room temperature” gets quite slippery.

[ToughButterCup]

2 hours ago, ProDave said:

[...]

The question follows on to SWMBO wants stone shelves when we build the larder to "keep things cool"  I had previously dismissed that as an old wives tale.

[...]

 

Dave, let me let you into a secret. .... Thats not going to go down well. She wants stone shelves? Give her stone shelves.

By Friday. With a smile. Fitted Saturday 9.30. Latest.

You have been warned.

[tonyshouse]

my butter is still soft and easily spreadable lives on granite worktop  ?