WILLTEC glue-up flat acoustic panels provide superior sound absorption and limitless design possibilities at economical costs. Rethink direct-apply, glue-up wall and ceiling panel applications. pinta acoustic’s lightweight, smooth-surface WILLTEC Flat Sheets are readily available in a variety of shapes, sizes and thicknesses.. Regardless of the finish option, WILLTEC foam is Class 1 fire-rated, according to ASTM E 84 for flame spread and smoke density. WILLTEC natural meets the corner burn test UL 1715.