So the fraynot fabric is glued on to the cover board; now the new bookcloth strip is glued straight on to it. The width of the glued down strip is important – it has to be enough to create a sufficient turn-in at the head and tail and also the edge should coincide with an impressed line on the cover cloth where there is one (and there very often is).
Now the new cloth has to be lined, as normal for a cloth spine. Use stiff paper or thin card but thinner that the old liner you took off at the beginning. You want to replicate the stiffness of the original, but after the repair there will be two layers of cloth on the spine, not one, so make the liner a bit thinner to compensate. Make sure the grain of the liner is up the spine.
As soon as you have glued the liner in place fold it round the back and hold it in place for a few minutes – this will set it in the shape you want.
Attach the other board as before – fraynot fabric and new cloth on top, under the lifted edge of the old cloth.
Now glue down the lifted edges or the original cloth on to the new cloth – use glue (sparingly) not paste as paste will penetrate the cloth and may stain. Then do the same with the flap of the old spine strip.
Next, the head and tail of the spine need to be turned in. There is a risk of getting glue on to the surface of the pages at top and bottom as you try to fold glued flaps into the hollow and to avoid this I use a piece of flexible acetate (a piece of thin card will do just as well but the acetate is better as it can be wiped clean each time and re-used indefinitely).
Then fold the little flaps at the top corners of the boards over to meet the top edges of the endpapers and set in place with a fold of release paper, a fold of thin card and a small butterfly clip.
All that remains is to colour frayed or rubbed areas with acrylic paint, paste down any odd frayed bits and polish the whole thing.
NB In this case the corners were OK – I will show how to improve bent or damaged corners another time.
A reminder! This is a repair, not a restoration, so there will be small lumps or creases and the colour match will not be exact. But it will work as a book and will not be harmed by normal use.