I was taught abrasive spark plug cleaners were an unacceptable method of cleaning plugs, so I have never owned one. Some gas engine manufacturers' also warn against their use.
The use of abrasive cleaners can allow abrasive media particles to become trapped in the crevice between the insulator and the metal plug base leading to misfiring. Media particles can also later become dislodged and ingested into the combustion chamber and cylinder. Erosion of the porcelain insulator and metal electrodes is also a concern.
An acceptable method of cleaning spark plugs I learned is to first use a brass or nylon bristle brush to remove the deposits from around the center electrode, the insulator, and the ground electrode.
Next, the most important part of the cleaning task is using a spark plug cleaning tool with a slightly rounded blade to scrape around the depths of the crevice between the insulator and the metal base using caution not to crack the insulator. This tool looks like a feeler gauge blade rounded length ways to fit in the crevice. Cleanliness of the crevice was stressed to prevent intermittent misfiring.
Compressed air is then used to rid the crevice of loosened deposits. The plug is then cleaned with solvent, dried and inspected for damage to the center electrode insulator.
A propane torch is also acceptable to use after the solvent cleansing to totally evaporate the solvent and remaining petroleum deposits. The plug must be well heated then allowed to cool to the touch by itself so the torch is infrequently used by most people when pressed for time.
Both electrodes are now inspected to determine if the plug is serviceable for re-use. If deposits remain on either electrode that cannot be dressed with a file or the electrodes are burned rounded, replacement of the plug is suggested.
If everything checks out good and the plug will be re-used, the most accurate method of adjusting the air gap between the center electrode and the ground is with the proper sized electrode bending tool used in conjunction with a wire gauge, not a flat blade feeler gauge.
Today's spark plugs installed in modern engines allow electrodes to burn to the point of necessary replacement before fouling occurs so cleaning is no longer necessary.
Plugs must be changed or removed and inspected at factory recommended intervals' because thread seizure between the plug and head can become an issue long before the plugs fail to spark or become fouled.
You do not have the required permissions to view the files attached to this post.