Spheretex Sphere Core SBC

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CarbonCore’s Sphere Core SBC is a pre-compressed, stitch-bonded glass fiber material which is volumised by embedding thermoplastic microspheres.

This product is particularly suitable for wet-on-wet process for producing both stable and light homogeneous laminates at the same time. The excellent characteristics result from the complete impregnation with ca. 40% by volume of the same resin used to laminate the skin layers. This sandwich material which can be laminated substitutes balsa, PVC foam material and other core materials but has the advantage of being able to adjust to the mould three-dimensionally.

This product is available in 6 mm, 8 mm and 10 mm thicknesses.


  1. Cut SphereCore SBC and the covering glass layers in the required shape. SphereCore SBC can easily be cut by using knife or scissors.
  2. Calculate the required amount of resin for all layers. For SphereCore SBC you will need approx. 400-450 g/m²/mm: e.g. SphereCore SBC 8,0 mm = approx. 3,2 kg resin.
  3. SphereCore SBC is compatible with UP and VE resin. We recommend to use standard resin for hand lay up process. Best results are achieved when using resin with a viscosity of approx. 350-600 mPas. If you are not sure if your type of resin can be used, you may laminate a small piece of SphereCore SBC for testing. If the resin is absorbed from the material within 20-30 seconds, the resin can be used for laminating Spherecore SBC.


  1. Laminate the first glass layers on the gel-coated mold as usually and de-aerate these layers. Important notice for thick laminates: Adjust your resin system to control exothermic reaction at low level. The first glass layers can be laminated in one shot and cure before continuing with the core. However, SphereCore SBC should always be laminated onto one glass layer wet-in-wet to ensure perfect bonding of core and covering layers.
  2. Firstly impregnate the zig-zag side of SphereCore SBC with approx. half of the resin amount that is required for the core.
  3. Place SphereCore SBC onto the previously laminated glass layers with the zig-zag side facing the mold. Impregnate SphereCore SBC until the recommended amount of resin is used and de-aerate the material.
  4. While de-aerating, SphereCore SBC can easily be shaped. The edges are flattened by slight pressure of the roller. During this step you may also flatten overlapping parts or connect adjoining layers of SphereCore SBC
  5. Continue by laminating the covering glass layers onto SphereCore SBC and de-aerate them as usual.

Mold Construction:

SphereCore SBC is the ideal core material for making durable and light molds – – – Why?

Stability of shape: Due to its low resin consumption (approx. 400-450 g/m²/mm) and when combined with mold resins, shrinkage of the mold is almost eliminated.

Easy and efficient processing: Dry SphereCore SBC material can be cut in the required shape simply by using scissors or a knife. When impregnated with resin, the material gets soft. Overlapping areas can easily and entirely be flattened. Wet-in-wet processing considerably reduces working time.
Resin compatibility: SphereCore SBC is compatible with UP, VE resin with a normal hand lay up viscosity. SphereCore SBC HT is compatible with epoxy resin.
Durability: Its high impact strength ensures durability and prevents damages from demolding.


Below please find some suggestions for composite molds made with Sphere.core SBC:

Small mold Gelcoat

(11 mm thickness) 1 layer CSM 225 g/m²
2 layers CSM 450 g/m²
1 layer Sphere.core SBC 6,0 mm
2 layers CSM 450 g/m²
Laminate these layers wet-in-wet

Medium-sized mold Gelcoat

(16 mm thickness) 1 layer CSM 225 g/m²
2 layers CSM 450 g/m²
1 layer MX 600 g/m² + CSM 450 g/m²
1 layer Sphere.core SBC 10,0 mm
2 layers MX 600 g/m² + CSM 450 g/m²
Laminate these layers wet-in-wet

Big mold Gelcoat

(23 mm thickness) 1-2 layers CSM225 g/m²
2 layers CSM 450 g/m²
1 layer complex MX 600 g/m²/CSM 450 g/m²
1 layer Sphere.core SBC 8,0 mm
1 layer CSM 300 g/m²
1 layer Sphere.core SBC 8,0 mm
2 layers complex MX 600 g/m²/CSM 450 g/m²
Laminate these layers wet-in-wet
++ For molds made in VIP, we offer SphereCore SBC IP. Please contact us for more detailed information++



Spherecore SBC is an excellent solution for making transoms up to 70 mm(2.75″) thickness. – – – Why?

High mechanical properties: Laminates made with Spherecore SBC are more resistant to pressure than laminates made with most other core materials. Furthermore, the thermoplastic microspheres inside SphereCore SBC absorb vibrations.
Water resistance: The water absorption of Spherecore SBC is comparable with solid glass laminates.
High shear strength: SphereCore SBC can be laminated and shaped wet-in-wet to connect the transom with the sides of the boat. In this way, stress is transferred to the hull of the boat. This helps to avoid microcracks in the intersection between transom and hull.

Transom Construction with SphereCore SBC

Transom Construction with SphereCore SBC

Here is a lamination suggestion for a transom of approx. 55-65 mm thickness:
++ Laminate two layers of SBC around the corner (as shown in the drawing)
to firmly connect the transom to the side walls and thus transfer stress from the transom to the hull ++


  1. Covering glass layers (outside) 7-12 mm
  2. SphereCore SBC 10,0 mm
  3. CSM 0,6 mm
  4. SphereCore SBC 10,0 mm
  5. CSM 0,6 mm
  6. SphereCore SBC 10,0 mm
  7. CSM 0,6 mm
  8. SphereCore SBC 10,0 mm
  9. Covering glass layers (inside) 7-12 mm