When gilding outside, it is best to 24k Pure Gold Triple Strong Leaf or the Ducate Double Polish. The leafs are more durable and brighter, which last much longer in extreme weather conditions than other gold leaves. Hence the Ducate Gold Leaf is most prefered by Headstone makers and historical building gilders. The best gilding size for outdoor that goes perfectly with the Ducate Gold Leaf is the high gloss Instacoll Base Size (yellow or clear). The Instacoll Activator is needed to reactivate the base, but only if the size dried out before you finished gilding. For more info, read How to use Instacoll Gilding Size. You might also want to seal the gold leaf using a varnish to protect the gilded surface: Gold Leaf Varnish.