First stir the black gloop till smooth and all the linseed oil is amalgamated.
Then with the dog's toothbrush (only kidding, dog!) force it under the lead. Make sure you don't leave any gaps; make sure you work at an angle to the lead, or you'll simply pull it all back out again. Realise why you were allowed to do this bit of the job.
Keep going. Be thankful you decided against starting this at nine o'clock last night, but wish you'd thought of bringing a cup of tea up to the attic with you.
It's hard to get a gloopy latex glove off in order to take a photo. The cats and the dog are queuing outside the attic door, making faint disgruntled noises; they can't bear being locked out. But you just know what would happen: this black cement would be jumped on, then trodden round the house and onto the beds.
Leave it to dry a little while you straighten your back, drink tea, walk the dog. The walk doesn't take long because you are ambushed at the end of the street by Millie, and don't want her following you anywhere with traffic. So we all trot up and down the back lane, followed by Lottie on the yard walls, her tail held aloft like a magnificent plume. Somehow both cats consider this a great treat, walking the dog with me.
Back to the cement. Sprinkle with chalk, which will absorb the excess oil. Panic a little at this stage, worry that you've done this wrong, and look up the instructions, both in a book and online. They contradict each other. Too late now, anyway. It's been so long since I did this, and I've sort of lost my nerve. Tricia is in Carlisle and not due back till this evening.
Buck up, you wimp; what's the worst that could happen? She could only kill you. Just be glad that she only let you do the back of the panel.
Using high-tech tools, a sawn-off scrubbing brush and a plastic fid, clean up your glass. Wait for Tricia to come home and tell you that YOU'VE RUINED IT!!!