Review of VENDIA marine plank by Adrian Morgan

Last April we wrote about Scottish Adrian Morgan who was fascinated by VENDIA marine plank and built Bob - 4,8 meters long skiff. Adrian found VENDIA marine plank from Richard Jagel's article in WoodenBoat magazine and wrote also a review of VENDIA marine plank himself in the same magazine later this autumn (issue September/October 2015). 

Read more of Adrian's experiences in the original article below and see how VENDIA marine plank was like in the hands of boat builder - writer.

Original article >>

The MUF adhesive used in VENDIA marine plank

Phenol formaldehyde adhesive is the most commonly used glue in marine plywood. It is water-resistant and commonly used in plywood industry. Originally the phenol formaldehyde adhesive is colourless but effect of air and oxygen convert the phenol into brown. That is why the dark glue seams stand out in plank board joints and edges if wooden boat is made of normal marine plywood.

When developing VENDIA marine plank our goal was to create a marine plank that is beautiful and durable. We wanted to get rid of the dark seams of normal marine plywood. When we started to develop VENDIA marine plank, one of the criteria in addition to the water-resistance was that the glue should be colourless. Our choice was MUF adhesive because of its colourless feature, water-resistance and strong references. MUF adhesive is commonly used among high-quality marine plywood producers.

The MUF adhesive is a two-component glue including adhesive and hardener. It is Weather Boil Proof (WBP) glue and meets the requirements of British Standard 1088 for marine plywood. The glue has passed the boiling test, which means that the glue must withstand boiling of 24 hours. In addition to boiling test, we have also made the absorption test of impregnating agents. In the test we had Owatrol, Hempel and linseed oil mixed with zinc naphthenate and it proved that all these impregnating agents were absorbed well also through the glue layers.

What is the difference between VENDIA marine plank and plywood?

There are certain similarities and differences between VENDIA marine plank and plywood. Few weeks ago we wrote (link) about the differences between sliced and peeled veneer. VENDIA is always made of sliced veneer and this is one of the most important differences between VENDIA and plywood. But there are also other differences, for example structure, glue, raw material, form of the final product, and finishing.

Structure

Glued structure is the common feature of VENDIA and normal plywood but there are also essential differences. Plywood is completely made of cross-laminated veneers, which means that every second veneer is lengthwise and every second is crosswise veneer. The idea of cross-lamination is to reduce the tendency of solid wood to crack and also to make the panel stiff across all directions. The crack resistance, longevity, and longitudinal stiffness of marine plank are important features when building a wooden boat. Many boatbuilders prefer VENDIA to the plywood because VENDIA has the maximized longitudinal stiffness whereas plywood is stiff across all directions. VENDIA marine plank has crosswise veneers only the amount what ensures the crack resistance of the marine plank. Depending on the thickness, there are 1-2 crosswise veneers in VENDIA. This structure ensures the crack resistance but keeps the other good characteristics of solid wood and increases the longitudinal stiffness of the marine plank. Plywood is made of veneers that have the same thickness, so after the calibration the face veneer will be the thinnest. Compared to VENDIA the normal plywood is harder to work with because of the thin face veneer and the crosswise veneer right below the face veneer. In VENDIA the face veneer is always the thickest. 

The structure: VENDIA on the left and softwood plywood on the right. (The picture on the right borrowed from: lahdenmaki.fi)

Glue 

Commonly used glue in plywood panels is water resistant, brown phenol resin adhesive. In VENDIA we use water resistant, colourless MUF adhesive (melamine-urea-formaldehyde). MUF adhesive is commonly used for example in traditional marine plywood, so it is very suitable also for nautical environment. Clear advantage of MUF adhesive is its’ neutrality. When working with plywood the phenol resin adhesive appears as a dark seam in the edges and joints of the plank because of the plywood’s structure. Colourless MUF adhesive is in turn indistinguishable. 

Commonly used glue in birch plywood is brown phenol resin adhesive.

In VENDIA we use colourless MUF adhesive.

Raw material

Raw material of VENDIA marine plank is Finnish, old-grown pine butt logs, which means that the raw material is the same high-quality wood as traditionally used in wooden boatbuilding. The vast majority of plywood is manufactured from lower quality raw material, which weakens the longevity of plywood when considering boatbuilding. Wood species have also an impact on the longevity. Birch and Okoumé are faster decaying species while conifers are generally more resistant to decay.

Form of the final product

The fact that VENDIA looks more like natural solid wood and plywood doesn’t, results mainly from the differences between sliced and peeled veneer. Also the form of the final product affects in the appearance. Plywood is manufactured and sold in large sheets while VENDIA already in finished planks. Each VENDIA marine plank is handmade and sliced veneer is centralized in the middle of the plank according to veneer’s pattern. 

Spruce plywood on the left and Okoumé on the right.

Finishing 

There is also a difference in the features of impregnation. In absorption test of impregnating agents, the absorption of impregnation agent was 1 ½-2 –fold better in VENDIA than in birch plywood.