Polyester (PET)
Polyester is the workhorse substrate for vacuum deposited materials.  It is a low cost, optically clear substrate that is suitable for many applications.  Sheldahl uses primarily DuPont Mylar in applications calling for PET substrates.  Sheldahl routinely coats substrates from 1.5 to 175 microns thick.

Polyimide (PI)
Polyimide can be used in many environments that PET cannot withstand.  Polyimide can be used in environments that see intermittent temperatures up to 400°C and continuous temperatures up to 290°C.  Polyimide's drawback is its characteristic amber color and comparatively high price.  Sheldahl normally uses DuPont H or HN grade for aerospace applications, and can obtain other grades as needed for special projects.   Sheldahl routinely coats substrates from 8 to 125 microns thick.

Polyimide is also available in two carbon filled (black) forms when high optical absorptance is desired.  Sheldahl maintains a stock of DuPont 100CB (non-conductive) and 100XC (electrically conductive) black Kapton films.  When an extremely matte surface is needed, Sheldahl's Thick Film Black (see the adhesives section) can be used in place of 100CB or 100XC Kapton.

Fluorinated Ethylene Propylene (FEP)
FEP is a high performance plastic that is clear like PET, but can withstand higher temperatures (up to 230°C).  Sheldahl uses primarily DuPont Teflon in applications calling for FEP substrates.  Sheldahl routinely coats substrates from 25 to 250 microns thick.

Glass Cloths
Many aerospace applications require rugged outer layers to protect the spacecraft from micrometeorite or other forms of damage.  Sheldahl has been a leader in providing light blocking coatings on beta cloth and other forms of glass cloths, and in building these materials into reinforced laminates.

In addition to these commonly coated substrates, Sheldahl has put coatings onto PFA, PVDF, PFV, PES, TFE, Polyethylene, polypropylene, polystyrene, polycarbonate, and Kevlar.