Blu-Tack is extremely useful in this respect as it can get into places that other erasers find impossible. This is particularly true of the final cleaning of highlights and re-establishing the correct tone of small areas of importance that have become muddied during the drawing process. To spot erase simply take a piece of Blu-Tack and pull a section out into a point then gently touch the point onto the spot that requires cleaning (or lightening or removing) and lift up. This will bring a certain amount of graphite with it. To continue cleaning, pull a new point and re-apply until the desired cleanliness is achieved. If you are lightening an area, try using the same partially graphite-loaded point, which will now pick up a lesser amount each time you apply it.

The example below (fig.1) shows the results of spot cleaning by Blu-Tack - the eye has had the all-important highlight returned to the necessary white. This is important as that single highlight often dictates the total range of tonal contrast throughout the drawing. In fig.2 and fig.3 the water at the base of the eye has also been brightened - areas so narrow (the images are 30% larger than life-size) that no conventional eraser could have succeeded - not even a kneaded eraser, which does not possess the inherent non-staining tackiness of Blu-Tack.

Blu-Tack was also used in all three cases to continually adjust the form and tone of each iris until the desired effect was obtained. The eraser is so gentle in its removal of graphite that incredibly subtle changes can be made again and again without damage to the surface.

Spot erasing was used here to improve the nostril highlight and the highlight on top of the nose, where the detail has been subtly lightened to blend into the highlight - using a very light touch, Blu-Tack is able to remove and fade just a proportion of the graphite, leaving the detail intact in a way that no other eraser can imitate.

I have found only one tool that will do this successfully — apart from the point of a scalpel, which can be used as a last resort! The requirement is for a soft eraser that can be reduced to as near a sharp point as possible and here the Staedtler fits the description. Of the two versions shown I use the top one — although this is now unavailable the 528-55 refills for the 528-50 below will fit the old (and more comfortable and precise) holder.
The eraser core is capable of being formed to a very fine point using a conventional pencil sharpener and, with care, can be used to erase very small areas — but this does need a mechanical rubbing motion which requires space so, unlike Blu-Tack, this eraser cannot be used in very restricted places.

This is part of the much wider subject of "negative" drawing, which I intend to cover at a later date. The basics, of course, simply involve removing already applied graphite to "draw" light or white shapes within it. Blu-Tack shines at this - the merest touch leaving a clear sharp-edged impression of a shape easily pre-formed in the putty. It is exceptional at suggesting background foliage, hairs in areas of deep shadow, anywhere that a suggestion is to be preferred over sharp focus. And for making additions at a late stage - having, for example, completed a section of foliage against a dark background you may decide that the section possesses some imbalance — a touch or two of pre-formed Blu-Tack will quickly add mid-ground foliage to redress the balance. A more determined touch or series of touches can even take 6B almost back to white if further foreground foliage is desired.
Cleaning the paper around your image on completion is a chore lightened by Blu-Tack. As I explained in complete erasure, form your putty into a fat sausage and roll it around on the area to be cleaned. This will efficiently remove all loose graphite and most of that embedded. Then clean away the last remnants with a clean soft art eraser for whiter-than-white results.

Whether you use drafting or conventional wood-cased pencils, it is always a good idea to clean graphite dust and grains from the business end whenever you sharpen it. I keep an old lump of Blu-Tack stuck to my drawing-board and just push the fresh pencil point into it for immediate cleaning.

There was a third use...? Something obscure yet unique... Oh, yes - you can use it fix your finished work to the wall!