2D Weightlifting Flour Sack - Sketch

For this week I had to animate a flour sack lifting a heavy object. I decided to keep the object simple, by using a boulder. However, I chose to give the flour sack legs as characterisation, and to explore to how to animate limbs.

First I drew the key frames and put them in the correct timing. This became my reference and 'base' for the whole animation.

Then I added a few inbertweens to keep the timing correct, and to help guide the fluidity of my motion.

I then drew all my inbertweens on my sketch layer, which looking back was a bad idea. I thought it would make the process easier as I had all the frames already sketched so I just had to trace over for my line art. However, I found that if I had done a few frames slightly wrong, then it messed up my entire animation. I found myself redrawing many frames to keep the same shape/volume of the flour sack.