Be good if you can post a pic of it.
I take it the bark is gone and you see exposed wood.
Remove all wax etc, no goo thanks, use eucalyptus oil to help remove it if it's sticky. Paint is generally applied only for looks and in the case of sunburn prevention white paint is used on some trees especially in orchards after a heavy prune.
Clean the area up.
Make sure where the exposed wood and existing bark meet it's a clean cut fine edge, if not get a sharp knife and fix it, this will help the new layer of growth.
What the tree needs now is good resources, mulch and moisture ... do not fertilize with high "N' products, use organic is best.
See this link on fertilizing.
http://www.weareallabouttrees.com.au/fertilizing.html
Keep the area under inspection, to keep bugs and borers off perhaps regularly spray with a natural product like eucalyptus oil, tea tree oil etc.
Eventually the area will be sealed off and maybe a new layer of bark will totally cover the area, till then, water, mulch, and light fertilize low on "N".
