The Tandem trademark uses several categories of selection of engineered parquet boards:
The “Select” grade includes products that may contain healthy knots up to 7-8 mm in diameter. It is also acceptable to have fallen or “dead” knots. Their diameter cannot exceed 3 mm. Some color deviations are also allowed. The discrepancies must be within the spectrum of natural colors of healthy wood. To ensure that the knots that fell out during the cutting stage do not disturb the aesthetics of the wood, they are filled with a special mastic. This grade should not have cracks or cores.
Grade “Natur” may have healthy knots up to 30 mm in diameter. The presence of “dead” knots is also allowed. Their dimensions should not exceed 15 mm. Standards provide for a wide range of shades of oak wood, as well as small discrepancies or defects in coloring. At the same time, small cracks may be present, as well as radial cracks in knots. If they fall out, the voids are filled with mastic.
Grade “Rustic” may include healthy knots without size restrictions. The situation with “dead” and fallen knots is more lenient, because their diameter reaches 25-30 mm. Inconsistencies in color, as well as shade defects, can be anything. Sometimes there are cracks up to 5 mm in width and 200 mm in length. The specification allows the presence of a core of any color. Cracks, as well as fallen knots, must be sealed with mastic.
Grade “Tobacco Select” includes parquet boards that have contrasting areas of coffee and chocolate shades. The material may contain healthy knots up to 8 mm in size. The standardization for “dead” knots is stricter: the diameter should not exceed 3 mm. Fallen knots are usually sealed with mastic. The presence of a core or small cracks is not allowed.
Grade “Tobacco Rustic” is a special selection, which has pronounced contrasting areas of chocolate and coffee color. The wood may contain healthy knots of any size. Fallen or “dead” remains with dimensions of no more than 25-30 mm may also be allowed. Small cracks are allowed by standardization. They can be up to 200 mm in length and 5 mm in width. Sometimes the wood contains a core of any shade, even dark. If a fallen knot or a small crack is found during production, they are filled with mastic.