Failures are more common than successes while experimenting. Here is a damaged coaster set that taught me much about making and glazing ceramics.
List of mistakes:
1. The lid did not fit after glazing. Should have accounted for the space glazing takes.
2. Should have scored and applied slip properly while making the coaster cover. It did not retain its shape after glazing. Walls got separated from the base. Disaster.
3. Top glaze not applied well. While using brush, one should apply glaze twice. Will remember this well now.
4. Coasters curved during firing and now are no more useful as coasters. Anything put on these tends to slide.
And while much of it was my wrong-doing, bad-luck added to the series of disasters. The adjoining piece in kiln exploded during the firing, leaving its white clay debris on my coaster set!
Lessons well learnt.