Fox's door frame is cracked inside. How to fix it?

1. First prepare some waste paper, cut it into pieces, then add alum and mix well.

2. Secondly, pour it into a container, add water, stir it again, put the container on the stove and cook it into a paste mixture, then fill the mixture in the gap and let it dry naturally.

Finally, put this container on the stove and cook it into a paste mixture. Then you can fill the mixture in the gap, let it dry naturally, and then paint the filled place with a repair pen.