DIY 'heat box' for stability testing

Formulating

DIY ‘heat box’ for stability testing

Posted by Margaret2 on February 28, 2016 at 9:07 pm

People,

I’ve been having a hard time finding a way to stability test my lotions/creams at 45 C because it’s cool in our house (18C, we use sweatshirts or sweaters if we’re cold).

I came up with this solution, and have already tested the temperature readings. It got to 47 C, and it held there for the 3 hours of testing . The 100 watt bulb gave me a temp. of 60 C, so I unplugged it.

PLEASE PROVIDE POLITE CRITICISM OR…PRAISE

Here is the LOI:

Dehydrator: a 10 shelf model. THIS IS THE MODEL WITH THE FAN ON THE BACK FOR HORIZONTAL HEATING & AIR FLOW VERSUS THE FAN ON THE BOTTOM (LESS EFFICIENT HEATING)

Trouble light with a 60 Watt incandescent bulb

Thin cutting board

Old pizza pan we don’t use

Thermometer with a probe that I can put into the dehydrator, with the thermometer outside of the dehydrator

Remove all the shelves from the dehydrator. Put one back, around the middle of the dehydrator.

Make sure you don’t have left-over food matter in the dehydrator that might catch fire from the light bulb, golly.

Put the cutting board in the bottom of the dehydrator, put the pizza pan on it, lay the trouble light on this (it will not burn) with the light bulb facing UP.

Put the thermometer’s probe on the shelf, turn on the trouble light, close the door, start recording the temp. you get with the shelf at different positions till you get a 45 C reading.

I found that putting an old bed sheet around the edges of the door kept the heat in & allowed the temp. to rise to 45C

I am using the trouble light as the heat source because it is WAY cheaper to replace a burned out light bulb than replacing the heater & fan on the dehydrator. This will be running for 8 to 10 weeks, remember. It’ll use 60 watts of energy/hour. I can also use the light from this setup as ‘mood lighting’ while watching T.V. in the living room ;0.

I will have various concoctions in the heat box at once, being heat-stability tested, so I won’t feel so guilty about using the 60 watts of hydro electricity.

Mike_M replied 8 years, 2 months ago 6 Members · 9 Replies
9 Replies

Microformulation

Member
February 28, 2016 at 10:41 pm

You also have to maintain humidity as well. Also, is this a set-up that could realistically run continuously for three (3) continuous 28 day periods and not deviate from the standards. Do you have monitoring to ensure the consistency and/or alert you when it goes out of spec?
ozgirl

Member
February 28, 2016 at 11:28 pm

Maybe look at chicken egg incubators for a cheap way of testing stability if the products are only for your personal use. I am not sure what their maximum temperature is but I would imagine it is around 40-45 degrees Celsius.

Hope this helps
luiscuevasii

Member
February 29, 2016 at 2:13 am

You could use a yogourt maker machine, they are unexpensive and could be used for more than 1 week, they works at 42-45 celcius.
Microformulation

Member
February 29, 2016 at 12:41 pm

Again, there must be monitoring of humidity as well. Under the guidance the suggested RH is 65%.
Margaret2

Member
February 29, 2016 at 3:37 pm

Hello,

Microformulation: My thermometer also shows humidity, so I can watch that too. However, I don’t have an alarm etc. since I am just making my things at home. I won’t be selling my things, at least, not in the immediate future. IF that happens, I’ll get REAL equipment for sure, and have my things lab-tested, etc.

Ozgirl: I looked at egg incubators, that’s how I started thinking about what I have around the house that I can use.

Luiscuevasil: Another clever idea for using stuff around the house .
Mike_M

Member
March 1, 2016 at 2:16 pm

I would be afraid of that bed sheet lighting on fire. If you go to home depot you should be able to find some sort of sealant that would work better to keep the heat in and increase safety.
Bobzchemist

Member
March 1, 2016 at 2:55 pm

I agree with the flammability problem. If silicone sealant won’t do, get some fiberglass cloth from the local auto repair store instead.
Margaret2

Member
March 3, 2016 at 5:24 am

Maybe I’ll tape cardboard around the door of the dehydrator instead. I’ll also go outside & hold the cardboard right against the cage of the trouble light (the heat source) when it’s turned on, & see if anything happens.

I can’t use anything permanent around the door of the dehydrator because I use it a lot to dry fruits in the fall.

Thanks for the tips!
Mike_M

Member
March 3, 2016 at 2:17 pm

What about going to a refrigerator parts store? You could pick up some stripping there that would work. Apply it with semi permanent adhesive and then yank it when you are using it for your fruit.

DIY ‘heat box’ for stability testing