When carved or other relief work is encountered, the round bristle brush, with extra long bristles and cotton flannel skirting, is nearly universally used. This type of renovator is shown in [Fig. 31].
Owing to the irregularity of such surfaces, intimate contact therewith cannot be obtained and practically no results will be had unless there is a large quantity of air passing through the renovator. When a large quantity of air is available, nearly as good results in cleaning this character of surface can be obtained by the use of the straight rubber-tipped corner cleaner, with a round opening about ³⁄₄ in. in diameter, as illustrated in [Fig. 32]. A very high velocity will be obtained through this renovator which will pull the dust out of inaccessible places. This form of cleaner is also very effective for cleaning the corners of rooms, where the floor and walls intersect, veritable dust catchers that they are, the cleaning of which is fully as important as it is difficult. Pigeon holes and other small compartments in safes, desks and similar furniture can be easily cleaned with this little renovator by simply introducing it into the front of such compartment.
FIG. 32. RUBBER-TIPPED CORNER CLEANER FOR USE ON CARVED OR OTHER RELIEF WORK.
FIG. 33. EARLY TYPE OF UPHOLSTERY RENOVATOR.
To be effective, this renovator must pass approximately 55 cu. ft. of air per minute and will require a vacuum within the renovator of approximately 3¹⁄₂ in. of mercury. Where only a small quantity of air is available, the author considers that it is better to make use of compressed air to blow the dust out of relief work, pigeon holes, and other inaccessible places and subsequently pick this dust up with other forms of renovators after it has found lodgment at more accessible points.
The cleaner which has met with the most disastrous results to the surfaces cleaned is the furniture or upholstery renovator. This has nearly always taken the form of a small carpet renovator. The type of upholstery renovator used for many years by the Sanitary Devices Manufacturing Company is illustrated in [Fig. 33]. This renovator had an inrush slot in the center, separated from a cleaning slot on each side by a partition extending to within ¹⁄₃₂ in. of the working face of the renovator. It had the hose connected into one end which was extended to form a handle. With this cleaning tool it was considered impossible to obtain a high vacuum within the renovator, as the inrush slots were supposed to act as vacuum breakers. However, as the surface of the upholstery is not firmly attached to the furniture it could be drawn up into the cleaner, closing the space under the partitions and permitting a high vacuum to be obtained. This caused the renovator to stick, but, owing to the narrow slot on each side of the inrush, the fabric was not caught.
Other manufacturers used a renovator with a single slot, in some cases as wide as ¹⁄₄ in., and instances are on record where the coverings of the furniture have been drawn up through the cleaning slot into the renovator and wedged so tightly that it was necessary to cut the covering from the furniture in order to release the renovator. To overcome this difficulty one manufacturer constructed the renovator in two pieces, secured together with screws, so that, in case the renovator became caught, it could be taken apart to release the fabric.
Many manufacturers have attempted to overcome this destructive tendency of the straight-slot upholstery renovator by inserting partitions on the cleaning face of the renovator, thus dividing the cleaning slot into a number of small slots the area of each not being sufficiently large to permit the drawing in of the fabric. These cleaners have followed two general forms, one having narrow slots running lengthwise of the cleaner, as illustrated in [Fig. 34]. This form reduces the destructive tendency to a great extent, but does not entirely prevent drawing the fabric into the renovator. If the partitions across the renovator be continuous, as indicated by the sketch, there will be a portion of the renovator which will not do any cleaning. Another form uses short slots, sufficiently inclined for the top of one slot to overlap the bottom of its neighbor, as shown in [Fig. 35]. This form of renovator is effective throughout its entire length and the small area of each slot makes it practically impossible to draw the fabric into the cleaning slot. It is considered by the author to be superior to the former type, especially when cleaning lace curtains or silk hangings or any other very light fabric.