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If you’re working on restoring a vehicle with a convertible top that needs to be replaced, you have some different options when it comes to materials. Haartz is the king of convertible top material, and its two main materials are Stayfast and Twillfast, but which should you use on your ride? We take a quick look at these materials to help you decide which is best for your application.
Haartz supplies both the OEM market and the aftermarket with various convertible top materials. Stayfast and Twillfast use a three-layer design. The elastomeric film that Haartz uses as the inner layer for both materials holds everything together, acts as the waterproofing and provides the acoustical characteristics too.
Stayfast is a robust material that will work with any convertible top application. 
On the surface, both materials are pretty much identical thanks to the solution-dyed acrylic they use that’s been treated with a proprietary water-repellant formula that Haartz has created. This treatment allows the materials to fight off anything that Mother Nature throws at them with ease. You can spot the difference between the two materials when you look closely at each. The Stayfast material features a square weave acrylic face, while Twillfast uses a twill weave acrylic for its face.
You can also tell the difference between Stayfast and Twillfast when you look at the backing fabric of each material. A top that uses Twillfast is going to have a polyester weave that’s more decorative on the underside, this gives the top an upscale look. The Stayfast top is just going to use a black cotton fabric on the underside that’s plain in appearance.
If you're looking for a convertible top material that will reduce cabin noise Twillfast is the best choice. 
Overall, a top made of Twillfast is going to be heavier than a top made of Stayfast material. This weight difference means a top that’s covered in Twillfast will be quieter when it’s up and you’re driving down the road.
The decision to use either Stayfast or Twillfast for your convertible top really comes down to personal preference for your application. Both materials have the same level of durability, so you don’t have to worry about one lasting longer than the other. The Stayfast material will give your vehicle a top that will last for years and look great. If you want a more upscale look inside the vehicle with less road noise, Twillfast will work best for you. You can see all the different options Haartz offers right here on the company’s website.
