We've got an older home which we're renovating - it's over 120 years old. More modern houses have flatter walls, but as we're not rebuilding the house that's not an option. Even with the modern gyprock (plasterboard) we've found the walls have a slightly wavy quality. Adding moulding to the wall and we're finding gaps between the wall and the moulding. There are also a few holes in the ceiling where the plaster has been damaged.
We considered using caulking, but its very messy and it doesn't hold paint so well. Drywall compound on the other hand is much easier to work with - you can shape it, sand it and paint it. But they don't make a caulking gun tube with drywall compound in it.
So what to do?
The answer has been inspired by my wife's mother - who would decorate cakes with an icing bag.
For this you will need:
* Drywall compound - we're renovating our whole house, so we have a box of it!
* A freezer bag
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Step 1: Put Up Your Moulding
We've put up the moulding already - nailed using brad nails and a compressor, and glued in place too. But as you can see from the moulding, where the ceiling isn't flat, and it's been damaged, there's a hole to fill will drywall compound. We wanted a very plain crown moulding so we're just using some 3" by 1" pine which we can then prime and paint when we're ready to go.
Step 2: Prepare Your "icing Bag"
Take an empty bag. We're using freezer bags because the plastic is thicker. Thinner bags will burst when you try and use it.
Take some of the drywall compound on a trowel or spatula - you will probably want a fairly blunt tool here so you don't shred the bag. Put the spatula right into one of the corners. Then using your hand on the outside of the bag, scrap the compound off into the bag. Get one or two good spatulas of compound into the bag. Don't fill it too full - you will need a lot of slack around your blob of compound.
Step 3: Cut the Corner Off the Bag
Conveniently we can see an air gap in the corner of the bag. Don't worry if you don't get this - but it was quite handy for the photo. Turn the bag so one corner is facing upwards. Twist the open end of the bag round so it puts some pressure on the contents of the bag and cut the corner off. The secret here is to not cut too much off as that will affect how big the bead of drywall compound is. The bead created in the photo was just right to fill the gap in the ceiling but too broad for under the other edges.
Unfortunately once you've cut the bag, you will find it very difficult to cut another corner.
The key to applying a good bead is to keep twisting the opening in the bag to keep the pressure inside the bag up to keep the 'nozzle' supplied with compound. Then using your other hand, you can guide the point of the bag and add the extra pressure necessary to get a bead of compound out. Trace a bead along the edges, the remove the excess with a sharp taping knife.