TECHNICAL BULLETIN SURFACE TAPE SHRINKAGE (DARK COLORED AIRCRAFT) When applying surface tapes to your aircraft you should be aware that all tapes are supplied in a virgin or unshrunk condition. This normally presents no problems when covering as the temperatures encountered by a finished aircraft are less than that required to cause the fabric tapes to shrink. There is, however, an exception to this rule. Dark colored surfaces in direct sunlight can experience temperatures of 210°F or 115°C!! For this reason we do not recommend dark colors ie. black, dark blue, dark green as a base color coat on fabric covered aircraft.
Keep in mind when a dark color is chosen for the final aircraft finish the temperatures the surfaces can reach are above the minimum shrinking temperature of the fabric tapes. This will induce thermal stress in the taped areas as the tape is trying to shrink but the glue is keeping it from it. The situation is more often noticed when the light weight (1.7 oz) tapes are used. It becomes a struggle between the glue strength and the stresses in the tape. If the gluing is a good one no problem will result. On the other hand if the glue job on the tapes is marginal the tapes in fact may shrink a little and expose a white line along one edge or the other.
If this happens one can normally just iron the tapes and ensure the glue joint is good and then repaint the area. The worst case would be to replace the tapes and repaint. To avoid this problem it would be wise to preshrink the tapes by ironing them at a temperature above anything to be encountered in the environment, say 250°F. This will preshrink them and eliminate any possibility of later shrinking after the job is done. It is only necessary to do this to tapes, which will be exposed to direct solar radiation ie. tops of wings, etc. Other tapes, which are on the underside of the aircraft will see no excessive temperatures.
If you do use dark base color use only Regular weight (2.7 oz) tapes not the light, weight variety. If you have any questions on this or ant other aspect of the fabric covering process please call us at 1-800-325-1650. WE WANT TO HELP YOU! Visit us at Our Web Site: airtechcoatings.com