I did extensive research into the matter of foam tapes for mounting spoilers a couple of years back. Here I impart my wisdom willingly, without reservation.
3M is the standard for mounting tapes. There are other manufacturers of mounting tapes, but 3M is the most popular, with the most available information and supply. Therefore, I only looked into 3M tapes. There may be other tapes that work just as well or better, but I didn’t look into those.
There are essentially two different classes of 3M mounting tapes suitable for automotive use: Acrylic Foam and Acrylic Plus. Both have a foam core with two adhesive sides: the liner side is designed to adhere to clearcoat paint and the non-liner side to LSE/MSE surfaces. LSE/MSE means Low/Mid Surface Energy, which are just classes of materials such as plastics and various composites that are difficult to adhere to. Here’s an explanation:
https://www.3m.com/3M/en_US/bonding...ence-of-adhesion/categorizing-surface-energy/
This use of differentiated adhesive sides and stability characteristics of the foam core is what determines which tape is best for a given mounting purpose. Here’s a brochure of 3M automotive tapes:
https://multimedia.3m.com/mws/media/1512486O/attachment-brochure-final-pdf.pdf
In general, we want to use Acrylic Plus tape because of a more stable foam core that does not stretch as much under equivalent pulling-away load, and the adhesive is more aggressive. There are two product series of Acrylic Plus tapes: EX4000 and PT1000. The datasheet below for EX4000 shows that while PT1000 offers slightly superior absolute hold strength, EX4000 has much faster adhesion times when used on LSE paint surfaces - such as those treated with a hydrophobic coating:
https://multimedia.3m.com/mws/media...sensitive-acrylic-plus-tape-series-ex4000.pdf
So it may take PT1000 series up to 10 days to reach full bond strength on LSE paint surfaces while EX4000 series fully bonds within 20 minutes. Clearly, we would like to use EX4000 series if given the choice, but PT1000 series is also a good choice if the car has non-treated conventional clear coat. These tapes come in three thicknesses, you can find these part numbers on eBay being sold in large rolls of various widths. Buy the width that fits your project:
0.76mm (0.8mm) - EX4008
1.14mm (1.2mm) - EX4011, PT1100
1.52mm (1.5mm) - EX4015, PT1500
In terms of thickness, the general guideline is that there must be about 0.5mm compressibility of the foam since the adhesive is pressure activated. Most trim parts have a small lip that is intended to hide the mounting foam and make the part as flush as possible. Remember, the tape has a foam core and will compress when pressed down. It’s important that the foam is taller than this lip by about 0.5mm. Without this clearance, it may be impossible to exert the pressure necessary for a full adhesive bond. So if the lip is 0.6mm tall, choose the 1.2mm tall tape. If the lip is 1mm tall, choose the 1.5mm tape. The 0.8mm tall tape is only good for mounting emblems, lettering, or any other trim piece that has little or no lip at all. Using the 0.8mm tape on a part with a 0.6mm lip will result in a partial bond because there won’t be enough pressure.
3M also sells Acrylic Plus tapes in blister packs under the following part numbers
1.2mm:
06382 (½ Inch x 20yd)
06383 (⅞ Inch x 20yd)
06384 (½ Inch x 5yd)
06386 (¼ Inch x 20yd)
1.5mm:
06397 (½ Inch x 10yd)
06395 (⅞ Inch x 20yd)
It is unclear whether these tapes are the EX4000 or PT1000 series and I didn’t look too deep, since the rolls are available on eBay with specific part numbers. Regardless, if you have access to these, they should be good to use, just treat them like PT1000 tapes and be mindful if the paint surface is hydrophobic or not.
Last thing: you must use a bonding promoter with the EX4000 and PT1000 tapes for the non-liner side that goes onto the trim piece. 3M sells the bonding promoter as part number 06396. You can find eBay sellers selling these either in 25-count boxes or as multiples of individual packs. Each packet will treat 150sq inches so you don’t need a lot of packs. One pack would certainly be enough for a spoiler. Remember, this is applied to the trim piece such as spoilers or body cladding, *NOT* the car paint. You brush the promoter onto the surface of the trim piece where the tape will be mounted, and let it dry, then mount the 3M tape.
Hope someone finds this useful.
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