Halloween Shrunken Heads Preservation?

Looking for information out there, from someone who has had experience making shrunken heads out of peeled and carved apples, for Halloween. Most of the websites and pages I have read up on, suggest that the proper way to preserve the apples faces, before the prescribed two-week drying, dehydrating and shriveling, is to give the apples a bath in lemon juice and salt. Would it be more prudent to outright soak the apples for a period of time, in said solution?? My experiments in doing a few of these so far, have had mixed results, as some of the apples seem to maintaining quite well, without rotting or molding...and others seem to be molding and rotting right away. Also, some of the websites have suggested that for quicker results, a slow baking of the apples, in a low-heat oven also works; has anyone out there attempted this, and what were the results?? Finally, for added preservation, once the apple has shriveled to the satisfactory point, would a thin coating of polyurethane help, and would it affect the apple, in any way?? I welcome any and all information, from anyone who has attempted this cool Halloween decoration idea.