Blank Selection Guide

Fiberglass Supply

Surfboard Blanks Home


How to select a blank:

We carry a wide variety of blanks and it can often be confusing as to which one to select when building a board.  This section will help guide you through the blank selection process.

In the last few years there has been an explosion in the variety of foam that is available for surfboard building.  Chemically there are two very different foam types and within each of those there are also variations.  The main foams are polystyrene, think coffee cups and cheap coolers, and polyurethane, think canned foam.

Polystyrene foam can come as extruded or expanded.  Extruded foam is a closed cell foam that is produced in solid sheets or blocks, a common example of extruded polystyrene is blue or pink board that you find at the hardware store.  Expanded polystyrene foam starts as little beads that are packed into a mold and then heated with steam, these beads expand and fuse to each other.  The beads are essentially closed cells however channels can exist between the beads.  Most surfboard blanks are made from expanded polystyrene (EPS).  The benefit to using EPS for surfboard blanks is that it can be blown in molds that mimic the shape of the blank, which reduces waste and increases shaping efficiency.  The other benefit to using shape molded EPS blanks is that the bonding and cell structure of the blank is far superior to that of a billet blown foam because the steam doesn’t have to travel a long distance to bond the cells in the middle of the billet.  Also the manufacturers that we carry use only virgin beads when blowing surfboard blanks.  Polystyrene blanks can only be used with epoxy resin systems.

Polyurethane blanks are the workhorse of the industry and have been in use for over 50 years.  Of course over time the chemical formulas have changed as new technologies have come available and as environmental laws have changed.  What is important in selecting a polyurethane blank is to understand that there are basically two cell structure types used in surfboard construction and those are cell gradient foam and consistent cell foam.  Cell gradient foam is less dense in the middle and cell density increases as you get to the outside skins.  The lower density foam is weaker and dents easier so it is important when choosing a blank with cell gradient foam to choose one that closely matches the final dimensions of the board.  It is also very important to not over shape the deck, taking just the minimal amount of foam off to get the shape you need.

Consistent cell foam does not have those limitations and can be shaped with impunity.  These blanks typically come relatively thick, which leave the shaper with a lot of options as to how to shape the blank.  It also is more work should a thinner board be desired. 

Polyurethane foam can be glassed with polyester or epoxy resins.

The purpose of having a wide variety of blanks is so that the shaper can choose a blank that closest fits the board he wants to build.  This reduces working time, reduces waste, and improves the quality of the finished product. 

Selecting the right size blank.

There are a number of factors that need to be carefully looked at when selecting a blank.  Depending on what you want to shape one factor may be more important than another so don’t take the order that these are put in to be the way it has to be after all shaping is about creating, pushing the boundaries, and trying something new.

Length- Blanks are listed in order by length.  The name of the blank usually indicates it’s length, for example US Blanks 9’3”Y however you need to check the blank catalog page to make sure that the given length is the blank’s true length.  The 9’3”Y for example has an actual bottom length of 9’ 3 15/16”, so it is almost 9’4”.  When selecting a blank you will normally want to pick one that is a couple of inches longer than the board you want to build but usually no longer than 6”.

Width- There are a couple of key width measurements that you will want to take into account when selecting a blank.  You will want to know or have an idea of how wide the finished board is going to be one foot from the nose, at the center (or wide point) and one foot up from the tail.  You then take these dimensions and consult the blank’s catalog page to make sure that the board will fit into the blank.  Areas that tend to be problematic are the nose and tail dimensions.  Also make sure to leave at least an inch or two extra, as blanks often get damaged around the perimeter or have other molding and processing marks around the perimeter that make trying to pull the full width out of them not a good idea.

Thickness- Check the thickness to make sure that you have enough foam there and if using a cell gradient blank make sure that there isn’t too much.

Rocker- Rocker is arguably the most important curve on a blank.  It is possible to shape extra rocker into a blank but a nightmare to try and shape rocker out of a blank.  If you find a blank that the board fits into but the rocker is not close enough to work we can special order blanks with rocker adjustments in them.  There is no charge for changing rockers and you can have it changed pretty much any way you like.

Stringers-We carry blanks with the most popular stringers and stringer sizes in them, however we can also order blanks with a wide variety of stringer options.  You can order multiple stringers, wider or narrower stringers, T-bands (two different pieces of wood glued together), colored glue, glue lines, paper stringers, colored foam stringers, etc.  Changing the stringer changes the cost of the board so if you have an idea about a stringer configuration that you want let us know and we’ll get you a quote.

Fiberglass Supply   11824 Water Tank Rd. Burlington, Washington  USA
Phone; (509) 493-3464 Fax(360)757-8284 e-mail;