Sheikh Yûsuf `Abd Allah Ahmad, professor at al-Imâm University
There are two general rules of Islamic purity law that are relevant to your question:
One: The default assumption about any substance is that it is pure. Only if its impurity is clearly established will it be regarded as impure.
This applies to the furniture and anything else that might come in contact with your clothing. The purity of these items should be assumed by default.
Two: An impure substance that is dry does not cause contamination for that which merely comes in contact with it. If the impure substance is wet, then if the wetness is clearly seen on the thing that comes in contact with it, only then will that thing be regarded as having been contaminated with the impurity.
This ruling includes clothing. Therefore, if a person's clothing comes in contact with an impure substance and that substance is wet, then, the article of clothing will be regarded as having been contaminated by the impurity only if that wetness can be seen or felt on the clothing. If the clothing remains dry, it will be regarded as uncontaminated.
In cases of doubt, a state of purity is always to be assumed. The previous state of purity is something certain. Therefore, the contamination of the clothing needs to be established with certainty, or at least an overwhelming likelihood.
And Allah knows best.
Source: Islam Today