105 º C removes all water from controlled sample until the weight does not vary more than 0.01%

I agree with Marcello. For higher precision one can weigh the dried sample in a vacuum oven (to negate the effect of ambient conditions and type of ceramic) and go to 0.001%. But, this be impractical or unnecessary.

It is the highest temperature that the samples are able to stand without changing its physical and chemical characteristics.

Keep an eye on the Oxigen content inside the oven, to avoid samples oxidation before removing the water. Try to do it with a neutral atmosphere, such as Nitrogen.

Good luck!

I think that depends on the type of the material tested. For natural stones for instance it's 70º C (+/- 5ºC) supported by a european standard.

EN 13755 is the european standard

Good luck for your work

you can adopt high temperature for short period (105 to evaporate water), or vacuum dryer, or low temperature with high air velocity (if possible). The best is you should measure weight of the specimen periodically and note the temp where weight becomes constant and no more reduction in weight.

hi USE SOP manuals for any such activities .

If you wold have written the purpose for drying sample (beyond dry mass) you may get proper answer. If you want to obtain dry mass irrespective of lossing tissue morphology, what you have do is use freeze dryer to get dry mass, usually this procedure i use for elemental analysis. Another for immunostaining and Transmission microscopy , you must fix the tissue and dehydrate , there is pretty standard procedure for fixation. if this is helpful i can provide you more information.

Best regards

Shahnaz

i forgot to mention that i will not use oven for any specimen when we have better techniques, if it is matter of drying biological specimen i will go with critical dryer rather than any oven. Now i think i misunderstood question if your specimen is not biological tissue , then i am very sorry.

yes, i concur with Marcelo but i will just add this, that due to varying environmental condition, then u include + 3 or -3 degree centigrade to that 105 degree centigrade

You can do a test with your material, try to do one samble for each temperature to see if there are diference. If not, that's great, your job it' s done. But if show up same diference, you can try a higher temperature, Antil there is no diference.

To add something slightly different to all the comments above, if you have access to it, differential scanning calorimetry (DSC) with a thermal gravimetric analysis (TGA) capability will give you very accurate values on low mass samples. The DSC curve will indicate any phase change if your sample is temperature sensitive while the TGA will allow you to determine the start and end temperature for driving off moisture. Once you have done this, you can carry out drying for larger masses with more confidence within the required range.

Many thanks for you guys' explanation, I'm really sorry, I forgot to mention the material I'm using. It's cement-based material, like paste, mortar or concrete. My purpose is to dry specimens until constant weight, then record the final dry mass to obtain the water content.

I would recommend DSC and TGA as per my post above then. I have used these techniques in the past, under a static (thermal) conditions to measure water evaporation during cement setting at room temperature. Any addition of heat will have to be quick and uniform through your sample to ensure setting reactions don't occur. If you are going to do this in an oven, preheat to desired temperature and spread the 'paste' thinly on the holder surface to ensure maximum evaporation. This will limit any setting reactions that might be driven by the elevated temperatures. I did something similar recently with calcium aluminate cements and the result was an easily removed powder.

In preparation of carbon samples we use 105 C. Please be careful though when trying to record the dry weight of your specimen. Depending on how hygroscopic your material is it may quickly start absorbing moisture from the air as you move it from the drying oven to the scale. What works well is working in a laboratory with humidity controlled environment and placing the scale inside a large desiccator.

I aggree with Slawomir using 105C, which is sufficient to remove evaporable water of cement-based materials. For instance, Standard RILEM TC 116-PCD uses this temperature to obtain total evaporable water content. About the moisture absortion when sample is taken out from oven for weighting, I think this short measuring time can be negligible.

100 deg C temp. is needed for evaporation of water. practically i use 110 deg C for cement and concrete materials. It may harm the concrete microstructure, although if you need to dry it go for 110 deg C for at least 1 hour.

DTA (differential thermal analysis) and TGA will give the changes upto certain temperature. you can check it out.

Oxidation of Carbonates usually starts at around 400 deg C.

Some use 80 deg C for drying, but i think it can't remove the water completely. Min 100 deg C is required to transform water to gaseous stage from liquid stage.

Barry's suggestions above are quite good for describing and quantifying phenomenologically what you have in the sample. Additionally, I believe the following reference may help assist in determining what stage the cementitious material is in when doing your analysis:

PK Mehta and PJM Montelro's Concrete: Microstructure, properties and materials.

If you are monitoring the stages of conversion or following a reaction, this will help with the understanding of what you are looking at. given the type and grade of the cementitious source.

temperature dependance varies with the material being analyzed

Most of my cement or concrete specimens have long curing ages or drying process before the oven drying to measure the dry mass, therefore, any forwarding hydration or setting reactions due to the elevated temperature may be negligible. Hence DTA (differential thermal analysis) and TGA analysis to identify the changes can be avoided.

You must tell more information about your material. To be able to help you.

is it polymer(thermoplastic or thermoset) and even the type of it or ceramic or any kind of organic materials.

Be more specific.......

Our lab uses 65C and overnight. This is to avoid destroying hydrated minerals in the sample

Thanks Tom's lab information. However, to cementitious materials, 65C may be not enough to evaporate all the evaporate water, 105C is a common method used in the literature.

Thanks a lot to Arunachaiam for your standard support.

It is better to fix 105°C, because less than 100 degree (boiling point of water) no good result can be expected and its 24 hours duation of drying as per std pro. else tightly bound hygroscopic moisture can not be removed

Maybe will you be interested by the following paper

Effect of drying on cement-based materials pore structure as identified by mercury intrusion porosimetry: A comparative study between oven-, vacuum-, and freeze-drying

in Cement and Concrete Research, Volume 31, Issue 10, October 2001, Pages 1467-1477, by C. Gallé.

Some comparisons are performed over different methods and the impact on pore structure is studied.

Thanks, Alexis, the paper will be useful.

The protocols I use for my research all state 105C for 48 hrs as the standard, please see Soil Sampling and Methods of Analysis (Carter & Gregorich 2008 [2nd ed]). This allows for the removal of all water attached to soil particles however it can lead to the volatilisation of organic matter which may account for some mass loss. Sandy soils generally do not need as long or as high a temperature as clay soils as their water is not as tightly bound. The easy way to test if the water has been removed is to weigh the sample after you have dried it...then dry it some more and weigh it again. If the weight is constant at all temperatures and over time then you can be sure you have removed all of the water from the material. 

Thanks, Stephen, your comments are helpful. 105C has been used to remove all removable water in cement and concrete. I learned from you that 105C is also used in soil research.

Merry Christmas.

Zhigen

I agree with the above answers, generally 105 degree C has been used to dry the soil or remove moisture in the soils of the field experiments mainly because Carbon present in the soil resistant upto 105 degrees and later on carbon will undergo burning. Where as in plant samples, the prescribed temperature will be 65 degrees, because plant samples will be burn if the temperature exceeds 65c.

Thanks for your comments for drying temperature used to dry soil sample, G A Rajanna.

Hi, the french standard for porosity accessible to water is based on a 105°C drying process (NF P 18-459, march 2010) . As important as the temperature level is the temperature holding time...the french standard considers a dried state when mass concrete  variation < 0,05% between 2 measurements spaced 24 hours apart.   Best wishes. Maxime

Dear

If the soil contains organic matter or gypsum, then the suitable drying temperature is 45 °C,  the drying to a constant weight is the target of water content determination and not the required temperature since it is variable depending on the chemical composition of the soil.

I agree with G A Rajanna.

I have interest in this recommended oven soil drying temperature and duration. high temperature with short duration one get same results as lower temperature long drying duration. What is the standard recommendation

In soil science, gravimetric water content (g/g) is determined after heating about 1 g of soil to 105 C (actually, between 100 C and 110 C) in a drying oven for 24 hours (actually, only a negligible amount of water is left after 8 hours in a pre-weighed 25 ml beaker, then cooling to room temperature in a desiccator, and weighing on an analytical balance to 0.0001 g. Temperatures above 105 C can remove water from hydrated minerals that should not be in included in a measurement of gravimetric water content. If you measure the bulk density of the soil, then you can determine the volumetric water content of the soil. The chapter here by Walter Gardner is the standard in soil physics: https://dl.sciencesocieties.org/publications/books/tocs/sssabookseries/methodsofsoilan1

Dear

As per ASTM, the drying temperature is 100_110 degree centigrade for a duration of 24 hours. Such standard may not be suiable for all types of soil especially those contain gypsum and or carbonates.

Mr G A Ranjana.

I have a question on your answer . How long should the sample placed under 105 degree centigrade??

Dear

The oven drying process as per ASTM is for a constant weight, you can check the weight of the sample after an elapsed time of oven drying, and when the weight does no show significant change then that will be the required oven drying period.

ASTM requires 105 C For 24 hours.

Dears;

As per ASTM D2216, the drying temperature is about 105 c. This temperature is quite true for soil which contain small amounts of salts and organics.

In order to reduce the degree of dehydration of gypsum in those materials containing gypsum, or to reduce decomposition in highly organic soils, it may be desirable to dry these materials at 60°C or in a desiccator at room temperature.

I agree with Prof Saad Sarsam for drying temperature of Gypseous soil.

Thanks a lot dear Prof @saad sarsam...

According to the ISRM suggested methods, experimental rock specimens in laboratory test were dried in 105°C oven for a period of at least 24 hours.