Hi Vicki, place your pine cones in a bucket and pour undiluted leach over them to cover. Place lid on the bucket and let sit for a day, then remove and rinse the pine cones and air dry on paper towels or newspapers.
Undiluted bleach is messy stuff. Be careful not to get a drop on anything else and wear gloves & eye protection.
Here you go Vicki
Or you could white wash them: https://www.redonline.co.uk/christmas/christmas-decorations/a505264/how-to-make-whitewashed-christmas-pine-cone-decorations/
Easy peasy, get a bucket and use Clorex Outdoor bleach with water. 50/50 solution. Let the pine cones sit in the solution for a few hours. They will close up, but will reopen when dry. If you want to dry really fast, bake them in a 250 oven for about an hour.
Wash 'em in regular laundry soap, air dry them and just spray the 'fake snow in a can' or silver paint on them. They look just as nice if not nicer. If you have Red & Green Ribbon, (Who doesn't at this time of year?) glue the ribbon on it with superglue. Voila you have a Hanging decor for Christmas. Easy Peasy. If you collect Pinecones, You Can make for $20 enough of these to hang them everywhere in your home and yet have enough to give away to friends and family and the poor.
It is especially nice and relieving to walk up to the Salvation Army Bell ringers and await they to ask: Would you like to make a Donation?
You say: Well Yes, Yes I would, Take one of these, I made a few too many...
And walk away knowing: That's what Christmas is about.