Halogen oven temperature accuracy

[wayupnorth]

Realised this morning that I already have a Type K thermocopuple adaptor for my (upmarket) multimeter. Accuracy is 1C. Checked the sensor in boiling water and it read 100.7C so happy with that.

Installed the sensor in oven base strapped to lower rack, in centre of bowl and roughly at the mid height of a mug. Also used extender ring.

To cut a long story short, with temperature dial at maximum the oven gets to 180C then starts to cycle. Removed extender ring, same results.

The oven seems to be a generic device badged by many suppliers:

http://www.ebay.co.uk/itm/231090634506? ... 1439.l2649

I realise this is not a show stopper as many other people are using these ovens with success by adjusting the cooking time. I guess the question is: at 180C is this hot enough for proper sublimation ?.

Anyone else out there with an accurate thermometer who can check their oven ?

[swimwivsquid]

The temp I think is borderline. I had a top element go in one oven and although it would reach 200c even with the convection it wouldn't sublimate evenly so I got another oven and it just about reaches 200 but mostly sits around 185 but because the elements are all working plus the convection the mugs are coming out fine. Best thing to do is to try one but give it 18 minutes to sublimate. Also try a design that would cover most of the mug and would show up any anomalies. Good luck.

[wayupnorth]

Well this is going to be fun.

Just tried a mug as suggested, monitored the temperature and it went up to 205C.... Let the timer finish and the result was ok but overcooked. I did wait to set the timer when temp reached about 120C to allow for preheat.

Next one went in for 15 minutes with no preheat, temperature between 180C & 200C. This one came out well (in my limited experience...) so will try more over the weekend. Room temp at 26C so not much fun slaving over the hot stove.

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[swimwivsquid]

I wouldn't bother with preheating. I tend to get the temp stabilised in the oven which usually settles down after about 20minutes and then put the mugs in. You might have to adjust the dial to get it to click on and off at the right temp but as I said after about 20 mins mine usually settles at the temp and stays there. There is a bit of lattitude with these things so don't get paranoid. Just get into a routine that works for you. I said 18mins as it works for my oven. Yours is probably a bit less plus I'm probably not using the same inks and paper combination as you. NB. I tend to use a separate timer for timing the process.

[wayupnorth]

Thanks, I guess as this is all new to me I will probably be worrying too much. I take your point about the timer, at least that is something I can have control over so one less variable.

[JBDesign]

People who use halogen ovens to bake polymer clay, (Fimo, etc) which is a temperature critical process, say that ordinary specialist oven thermometers are not accurate. Fimo make one for polymer clayers which is expensive but does the job I'm told. Might be worth looking into. Halogen ovens are hotter at the top near the bulb so maybe diffuse that with something like foil (?) Maybe not an issue with subbing mugs but i thought I'd mention it.

[JBDesign]

Thermometer is made by Staedtler.

[Quinsfan]

I turn my halogen oven temp to 200 turn the timer dial all the way round and put the handle down. I then start printing the artwork , taping it on and placing my 3 mugs into the clamps. By this time the halogen is ready, I do not have any thermometer only the ovens dial, and I place my 3 mugs in for 18mins. The only failures have been me not watching the time and leaving the room with less time left then I thought or if I am producing something very dark or a lot of black text and forget to reduce my times by about 1- 1 1/2 mins.
I don't preheat my mugs and leave them to cool naturally on a terracotta tile.