I’ve looked around here and I haven’t found much information on PVC stringers. Is anyone using them? I’ve been considering playing around with cutting my own blanks from block EPS, then adding my own stringers. It would just be fun to get creative with parabolic stringers, laminated woods, PVC (or other materials), colors, etc. I know others are doing this, so I’m wondering if anyone has an opinion on PVC (specifically expanded/foamed PVC).
Here are my questions.
What are the pros and cons to PVC?
What flex characteristics does it have compared to typical woods used?
Is expanded PVC easy to shape?
Should I stay away from laminating wood and PVC together if shaping the two materials require different tools?
I worked at a trim company that used to order 20’ sheets of PVC in various thicknesses. The stacks would ship banded together with 1/8" sheets between the pallet and the bottom sheet and then again covering the top sheet to help prevent the useable sheets from getting marked up in transit. We couldn’t give them away. I always thought they’d make a decent stringer. a little flimsy, but flimsy in the direction that it would not matter in a board. I only ever saw them in white and that would probably look great with some pigmented glue on either side. The process used to make them yielded a tough and cohesive skin, but they were more porous towards the center.
See if you have a PVC trim manufacturer near you, or any place that sells Koma, Trex, Wolf sheets for construction. Chances are if they do, they may also have some of these 1/8" sheets laying around as well.
What you want is the kind used by sign shops. The brand names are Sintra and Komatex. It comes in 4x8 and 4x10 sheets. The 10’ sheets were only available in white. 1/8" thickness is what you want. You can paint it before gluing with rattle can paint for a nice glue line effect. Very easy to work with and shapes well.
Greg Loehr did a lot of PVC stringers back 15-20 years ago. These were the solid material. I've seen the foamed product and it might be worth a try as stringer material. You'd certainly get a better skin bond along the stringer compared to the solid. Bonding while gluing up can be an issue also, it's not porous like wood so it should be scuffed to get some mechanical ''grip''.
As long as you rough up the plastic with 40 to 80 grit sandcloth ,flame treat then wipe down with 99% isopropyl alcohol, you’re golden.
The Sintra style material should be more flexible than an equally thick wooden stringer and have similar weight, if not lighter.
The foamed PVC would be a good choice for a board with a double stringer due to the flexibility of the plastic. imho.
The core of the foamed PVC is also somewhat porous ( like a micro aero chocolate bar ) . This will increase the bond at the edge of the stringer where it meets the glass deck and bottom.
I’m building a double PVC stringered board this fall, I’ll let you know how I like it.
I've used Comatex (sp) on a lot of boards. it comes in a variety of colors too. usually black or a wood color. Makes a wonderful board. PVC is a very flexible and makes a lively board. Best with EPS, Epoxy and PVC, good flex qualities. down side is boards flex and buckle. Never had one break, but they do buckle.
The trick is in the glue up. There is a special kind of glue out there (sorry wont tell) that has like a rubber cement type qualities and adhesion directions. You need something flexible to move with the board and stringer. if not the bound between stringer and foam will fail and delam will occur. And as Mikey D refered too the comatex does not have any pores like wood, so the material just sits on top of it. So using epoxy or Elmers glue is out of the question.