How to use wood treatment and varnishes

Before applying any varnish it is advisable to increase protection by applying a penetrating wood oil. The main purpose of this product is to increase the waterproof barrier of the system, to provide good protection against fungus and rot and provide a well  prepared substrate for varnishing. Jotun Yachting offers two traditional one component varnishes, and one cross-over product which is a combination of oil and varnish.

1. Preparation

Before starting, mask and protect surrounding areas not to be varnished with solvent resistant tapes or plastics.
Note: If the antifouling has already been applied, protect the underwater area to avoid dust, paint mist and any other type of contamination that may affect the performance of the antifouling.

2. Protection

It is also important to protect yourself with the proper overalls, gloves, goggles and mask. Adhere to safety instructions on the back labels and technical data sheets.

3. Stirring

It is essential to thoroughly stir any type of varnish. For up to three litre cans, use a wooden/metallic stirrer and for bigger can sizes, use a mechanical stirrer. The stirrer should be completely clean to avoid contamination of the varnish.

4. Application tools

  • Brush: The preferred method due to its properties of application and easy access to small areas. Must be solvent resistant. It is important to use a high quality brush to avoid loosing bristles.
  • Roller: A medium or short pile mohair roller, resistant to solvent should be used. Alternatively a foam roller can be used, but with this type there will be more air entrapment, so extra brushing work will be necessary to achieve a perfect finish

5. surface preparation

Regardless of the application method, the key factor for achieving a professional finish is a correct surface preparation. All areas to be painted must be washed with fresh water to remove dust, salts and other contamination. If the surface has stains of grease or oil, it should be degreased. Once the surface is clean and dry, sand it to obtain a good adhesion and a smooth surface. For previously varnished surfaces in good condition, sand with P280-P320 and remove all dust from sanding. Surfaces with minor damages, sand with P280-P320 and repair the damaged area before new varnish is applied. Small damages and scratches may be repaired by filling the damage with multiple layers of the varnish used
for the rest of the boat. Finish by sanding the repaired damage to achieve a smooth surface for the continued varnish application. For surfaces in poor condition, all varnish needs to be removed by scraping or sanding the surface, possibly with the help from a hot air gun.

6. Application

On top of new wood, apply several coats of varnish to protect the surface. To achieve good protection, apply 4-5 coats of one component varnishes. Apply thin coats to obtain a glossy and smooth finish. It is advisable to sand between coats to remove possible dust inclusions. This will help to achieve better leveling and a uniform thickness, and thus better finish with resistance and durability. Apply the recommended coats. Avoid applying under adverse conditions such as strong wind, high sunlight/heat (specially at noon in summer time), low temperatures or high humidity or rain. It is not recommended to add solvents as these reduce the thickness applied and there will be more risk of sagging, splashes, etc. However, if necessary to apply paint in strong wind or in high temperatures, it is possible to add between 5% and 10% (maximum) of solvent. Only use Jotun thinners and carefully read the product specific technical data sheet prior to use.

The recommended application system

  1. Apply 5-15 coats of Clipper I, wet-on-wet, as per the application guide. 
  2. Apply a first coat of Jotun Yachting varnish which should be diluted with 10% and 15% of the recommended Jotun thinner to help penetration.
  3. Apply three to four coats of the product. If long lasting protection is desired, a total number of 10-15 very thin coats should be applied. 
  4. As more coats are applied sand the surface with a fine grade to avoid defects and dust inclusions that may be visible on the following coats. 
  5. Follow the drying times and the recoating intervals as stated in the technical data sheet of each product. A good rule would be to apply one coat per day.
The best finish is obtained by applying thin coats in the same direction as the grain of the wood. Although not necessary, it is advisable to sand between coats with a very fine grade sandpaper to remove wood fibres, dust and other defects. By doing this, a uniform thickness will be achieved and the finish will be defect free for the following coats. Use good quality brushes and rollers in order to avoid fibres on the wet paint.

  • Do not apply in very high or very low temperatures, under strong sunlight or in strong wind.
  • Wet the floor around to avoid dust on wet paint. 
  • Stir the product thoroughly and every now and again during application.
  • Use high quality mohair rollers or solvent resistant foam roller. 
  • Apply thin coats following the direction of the wood grain. 
  • Apply 5-15 coats of Clipper I, wet-on-wet. If Clipper I is not available, the first coat of varnish can be diluted 10-15% to improve the penetration.
  • After the first coat, it may be necessary to sand with a medium to fine grade sandpaper to remove wood defects. 
  • Apply the product by brush at 45º angle to avoid brush marks.