A blackboard (also known as a Chalkboard) is a reusable writing surface on which text or drawings are made with sticks of calcium sulphate or calcium carbonate, known, when used for this purpose, as chalk. Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone. Wooden Chalkboard,Wooden Blackboard,Wooden Sandwich Board,Chalkboard Sign Jinan Tri-Tiger Technology Development Co., Ltd , https://www.jinanfurniture.com
A blackboard can simply be a board painted with a dark matte paint (usually black, occasionally dark green).Matte black plastic sign material (known as closed-cell PVC foamboard) is also used to create custom chalkboard art.Blackboards on an A-frame are used by restaurants and bars to advertise daily specials.
A more modern variation consists of a coiled sheet of plastic drawn across two parallel rollers, which can be scrolled to create additional writing space while saving what has been written. The highest grade blackboards are made of a rougher version porcelain enamelled steel (black, green, blue or sometimes other colours). Porcelain is very hard wearing, and blackboards made of porcelain usually last 10–20 years in intensive use.
Lecture theatres may contain a number of blackboards in a grid arrangement.The lecturer then moves boards into reach for writing and then moves them out of reach, allowing a large amount of material to be shown simultaneously.
The chalk marks can be easily wiped off with a damp cloth, a sponge or a special blackboard eraser usually consisting of a block of wood covered by a felt pad. However, chalk marks made on some types of wet blackboard can be difficult to remove. Blackboard manufacturers often advise that a new or newly resurfaced blackboard be completely covered using the side of a stick of chalk and then that chalk brushed off as normal to prepare it for use.
New cigarette packaging method
Patent Name Cigarette New Packaging Method Patent Applicant Han Jiyong Principal Applicant Address 271100 Fengcheng West Street, Laicheng District, Laiwu City, Shandong Province Inventor Han Jiyong Application (Patent) No. 200410002685.X Date of Application 2004.02.03 Certification Date Approval Publication No. 1650113 Approved Announcement Day 2005.08.10 Manual CD-ROM D0532 Main Classification Number B65B19/02 Classification Number B65B19/02; B65B11/00; B65D85/10 Sub-item Original Application No. Priority Abstracts This invention is an improvement of the cigarette packing method due to current cigarettes. In the packaging method, the filter tip is toward the open end of the cigarette box. When the cigarette is taken from the cigarette box, the hand is not sanitary to the filter tip; in addition, the end of the cigarette cigarette is not blocked and the tobacco is likely to be scattered; the cigarette packaging method is simple. The main points of the solution of the present invention (1) is to put cigarette cigarettes upside down into cigarette packs; (2) to plug the cigarette cigarette ends. Schemes (1)(2) can be implemented independently. The invention is applied to the packaging of cigarettes. Sovereign Items The scope of protection claimed by the present technology is that both ends of the cigarette box can be opened, and the open end is selected according to individual needs; the cigarette box is changed from the vertical side to the vertical side, and the side is the open end.