Methods of testing a honeycomb filter include the step of maintaining an average temperature of the honeycomb filter and/or fog within a range of from about 10° C. to about 30° C. and flowing a fog with moisture droplets into the honeycomb network of channels at the first end portion of the honeycomb filter, the fog including a relative humidity of at least 80%. In further examples, the moisture droplets include a mean droplet size of from about 1 micron to about 25 microns.