Guidance Notes for Painting Boats
Guidance notes to help when painting boats constructed from a variety of surfaces.
If in any doubt about any aspect contact us on 01234 273388
FERRO CONCRETE
It may sound strange to think of yourself floating on a “slab of concrete” however this is pretty much what a Ferro concrete boat is, except the concrete is low density and reinforced with an iron structure. The hull is formed in metal mesh and then filled and “plastered” with concrete. This process makes the vessel both cheap and relatively easy to make. Repairs are also fairly straight forward.
Unpainted New Surfaces
Preparation
Ferro concrete is porous and often has an uneven surface profile. If you are painting for the first time onto new work, the surface should be sealed first with a suitable primer sealer which is compatible with the finish coat system. This will block up the open “pores” or small holes in the concrete. Firstly any “salts” or efflorescence formed from the drying process (often seen as white powder) must be removed. This can be done by “washing” the surface with a dilute Acid Etch solution which dissolves any alkaline salts. Thoroughly check over the entire surface to ensure there are no cracks or evidence of structural problems. If there is, then speak to a professional. Whilst you may be able to make the repair, the context of any problem needs to be assessed.
Priming below the waterline
Teamac Chlorvar thinned 10% with Teamac V/607/15 thinners. Two coats will be required.
Priming above the waterline
Teamac Chlorvar thinned 10% with Teamac V/607/15 thinners. Two coats may be needed to provide a non porous and sealed surface.
Finishing below the waterline
Use the selected Teamac Antifouling Two coats are recommended.
Finishing above the waterline
Use the selected Teamac top coat system.
Previously Painted Surfaces
If the surface has been previously painted thoroughly check all areas. Ensure the surface is free from any efflorescence or salts. Remove any loose, fractious or “flaking” paint and spot prime with Chlorvar thinned 10% or a selected compatible primer. Sand down any good surfaces to help the new coating to adhere. Then apply the selected coating. Check for compatibility. Generally Teamac Antifoulings and Marine Gloss coatings have a good degree of compatibility. Care should be taken if using Teamac Chlorvar Chlorinated Rubber Paints or two pack systems.
GLASS FIBRE, GRP
Glass fibre was originally designed to be relatively cheap, easy to use and a low maintenance substrate. Whilst having distinct advantages over some materials GRP does require maintenance, both for protective and decorative purposes. Ultra violet light from the sun, saltwater, abrasion, wear and tear and the dreaded ”osmosis” all mean that protective coating are required.
Unpainted New Surfaces
Preparation
Lightly abrade the surface with 200-300 grade sandpaper to assist the adhesion of the coating. (Wear suitable dust mask). Dust off and ensure the prepared surface is free from any grease, oil, dirt or moisture and especially any mould release wax and grease.
Thoroughly degrease the surface. Inspect the whole area for damage and any blisters, which show that osmosis may well have affected the substrate. Make repairs as required.
If in doubt contact a professional especially in the case where osmosis is suspected.
Painting below the waterline; Antifouling
Apply one or preferably two full coats of Teamac Antifouling of your choice, two coats should ensure that no area is missed. For advice on selection for your water, sea conditions and boat speed contact 01234 273388 or sales@rejel.com
Check no areas have been missed and note the recommended launch times shown on the tin and in the antifouling brochure. Health and Safety as well as waste disposal information should be adhered to at all times.
Painting above the waterline
Proceed as in “below the waterline” then apply the selected colour of Teamac Marine Gloss directly to the prepared surface or P101 two pack Polyurethane if a higher performance is required.
Two coats should be applied, lightly sanding down between coats and ensuring the last coat is dry before applying the next. If changing colour from a blue to a yellow for example, ensure an even application for each coat and an extra coat may be required. (The use of Teamac Marine undercoat is not necessary for GRP substrates).
Previously Painted Surfaces
Preparation
On all substrates ensure the surface is clean, dry and free from wax, oil and dirt. Flaking paint work should be removed and old paint surfaces sanded. On GRP and Glass fibre it is important to ensure that the exposed substrate has been adequately abraded, this could be why the previous coating has come away from the surface in this area (use 200-300 grade paper wet or dry).
Preparation Below the waterline
Self polishing type Antifoulings should be checked for stability and compatibility before applying Teamac Antifoulings, in practice incompatibility is not often a problem (see compatibility chart on the Teamac Antifoulings page or contact 01234 273388 or sales@rejel.com)
Two coats are usually better than one providing better protection.
Preparation Above the waterline
Thoroughly inspect the entire surface. If there are any signs of physical damage, holes etc, to the surface or “osmosis” blisters then more substantial repairs than painting are required and you should contact a professional boat yard. If an inspection reveals no such problems apply as in “NEW UNPAINTED SURFACES”.
If using P101 two pack Polyurethane top coat check the compatibility with the existing coating first. For advice on using P101 two pack contact us if in any doubt.
WOOD
Wood is a natural material and as such is more susceptible to attack by plants, small animals and microbes than any other substrates. To prevent this it must be treated and protected with a durable effective paint system. Existing growth and infestation must be removed. Watch the moisture content; failure to ensure the timber is dry (this will depend on the type of timber but typically below 12-15%) will often result in micro blistering of the paint system and consequent coating failure.
Unpainted New Surfaces
Preparation
Before priming the wood should be dry, clean and free from grease. It is recommended that wood should be “sanded” to achieve an even surface. Check for damage, knots, rot etc. treat as necessary, with knotting marine filler or replace if required. Thoroughly inspect the surface to double check its condition. Check all joints are sound and repair as required.
Painting Below the waterline
Teamac Metaclor Underwater Primer must be used. Stir the paint well. Apply by brush or roller to wet film thickness of approximately 90-100 microns at 20 C. With good ventilation the paint should be touch dry after 3 hours and can be re-coated after 8 hours. One or two coats may be required depending on the porosity of the wood. Spray can be used but the best penetration for the initial coat is achieved by brush application.
After application check the primed surface to ensure there are no untreated/uncoated areas then apply two coats of the selected antifouling.
Painting Above the waterline
Teamac Penetrating Wood Primer can be used or Teamac Metaclor Underwater Primer for a stronger performance. One coat may be enough but two coats would be beneficial. This can then be over coated with Teamac Marine Undercoat and Marine Gloss.
P101 two pack Polyurethane can be used for enhanced performance as a topcoat on top of Teamac 2 pack Epoxy Primer.
Previously Painted Surfaces
Thoroughly clean and check the integrity of the existing paint and the hull.
Spot prime and treat any exposed areas. Then proceed as in “Unpainted New Surface”. Ensure any loose and flaking material has been removed prior to the application of any new paint. Check the moisture content of the timber if it has been exposed or soaked in water – moisture can take a long time to leave the timber and will cause small blisters in the finished paint film if trapped in the wood.
Vanishes & Oils
Vanishes are clear coatings generally used to protect timber. A marine varnish is of exterior U.V. resistant quality. The surface must be clean, dry and sanded smooth. Start with 80-120 grade, then finish with 200-300 grade paper. The surface can be wiped with a rag dampened with V/607/15 Thinners to help ensure all dust is removed or use a tack rag. Check for any damage and make the necessary repairs as required. Apply a first coat of Teamac Yacht Varnish slightly thinned with White Spirit. This will help the varnish penetrate into the wood. More coats can then be applied lightly sanding down between each coat (with 280-300 grade sandpaper) and ensuring the previous coat is dry before applying the next. The gloss and colour will deepen with each coat.
Teamac 2 pack Polyurethane Topcoat varnish will provide a high performance finish on stable timber but cannot be applied over existing single pack yacht varnishes. Teak oils can be used inside on hard woods which have a high ‘oil’ content and are not suitable for traditional varnishes.
IRON AND STEEL
Iron and Steel must be prevented form breaking down into their “salts” or “oxides” (i.e. rust). To do this water and air must be prevented from coming into contact with the surface – the oxidisation process must be stopped.
Unpainted New Surface
Preparation
Ensure that the surface is clean, dry and free of rust, mill scale and any loose or flaking material. It must also be thoroughly degreased. Mechanical abrasion, wire brushing or preferably shot blasting is the recommended method. A suitable primer should be applied to the bare steel as soon as possible to prevent the new exposed metal from “flash rusting”.
The performance of the paint system will depend on the quality of the preparation; short cuts here will result in premature paint failure.
Painting Below the waterline
Apply at least two coats of Teamac Metaclor Underwater Primer and two coats of the chosen grade of Teamac Antifouling Paint. Thoroughly stir the products and apply two good coats to achieve a film thickness of at least 70-80 microns of primer plus 100-120 microns of antifouling.
Alternatively two coats of Teamac ‘Ephidox’ 2 pack Zinc Phosphate primer will provide a high performance barrier followed by the selected antifouling (two coats).
Painting Above the waterline
Apply at least two coats of Teamac Metaclor Primer and two coats of Teamac Chlorinated Rubber Paint of the selected colour for excellent protection. The traditional system involves applying two coats of Teamac Zinc Phosphate Metal Primer, one coat of Teamac Marine Undercoat and two coats of Teamac Marine Gloss, which will provide excellent protection and value for money. For the highest specification use Ephidox 2 pack Zinc Phosphate primer followed by Teamac 2 pack Polyurethane Topcoat of the selected colour.
Previously Painted Surface
Preparation
Thoroughly inspect the substrate. Remove any loose or flaking material and remove or treat all rust. Spot prime in accordance with the materials used in “Unpainted New Surfaces” but if you are uncertain about the compatibility of the new paint contact 01234 273388 or sales@rejel.com.
Teamac Rust Convertor can be used to stabilise rust areas but there is no substitute for complete removal and re-priming.
Abrade the entire surface and check the spot priming for adhesion before applying the appropriate selected undercoat and topcoat.
2 pack Polyurethane should not be applied over existing single pack paint systems or if there is any doubt about the type of existing coating.
ALUMINIUM
Aluminium is widely used for marine structures – it is light as well as strong but it suffers from oxidation as does iron and steel. It must be coated to protect if from air and water and to provide the desired decorative finish.
Unpainted New Surfaces
Below the waterline
Use Teamac Metaclor Underwater primer. Stir the paint well. Apply by brush or spray to 90-100 microns wet film thickness at 20C with good ventilation. The paint should be touch dry after 2 hours and can be re-coated after 8 hours. Two coats are recommended followed by two coats of a suitable antifouling.
NB. The Metaclor acts as a barrier between the aluminium and the antifouling. Any coating damage in use must be repaired and a cuprous oxide free, antifouling is then recommended.
Above the waterline
Thoroughly clean the surface and then lightly abrade to assist adhesion, or use Teamac Etch Primer (black only).
Then prime with either Teamac Zinc Phosphate Primer or Teamac Metaclor Primer. After this you can apply Teamac Marine Undercoat and Gloss as appropriate. For a higher performance system use either Metaclor Primer followed by Chlorvar Topcoat or Ephidox 2 pack Zinc Phosphate Primer followed by P101 Topcoat.
Previously Painted Surface
Over existing paint ensure the paint is stable. Remove all loose and flaking areas back to clean aluminium then spot prime with either Metaclor or Zinc Phosphate Primer. Inspect the whole surface again to ensure no areas have been missed, thoroughly degrease and clean. Sand down all existing paint then apply the selected top coat.
Apply the selected undercoat and top coat as in “Unpainted New Surfaces”.
DECKS
Decks are critical areas. They are exposed to all elements (wind, sun, salt water) and also to the wear and tear of foot traffic. In addition they want to be safe to walk, stand and even run on! The best way to achieve this is to use an anti-slip deck paint which both protects the surface and helps grip. Shoes are a part of this equation. Using good footwear makes a difference. Teamac Suregrip is a ready mixed paint system, which contains aggregates to provide slip resistance.
Steel and Aluminium Decks should be primed first after a thorough cleaning. All rust should be removed from steel (an etch primer can be helpful on aluminium) prior to the application of Teamac one pack or two pack Zinc Phosphate Primer.
One or two coats of Teamac Suregrip can then be applied. Brush well out and avoid applying a thick film which will be slow to dry. Two well brushed out coats are superior.
GRP and Glass fibre should be cleaned and sanded to provide adhesion for Suregrip to be applied directly to the surface; again two well brushed out coats.
Wood decks must be checked, cleaned and then sanded before priming with Teamac Exterior Wood Primer. Two well brushed out coats can then be applied.
Teamac Deck Paint can be used in areas where slip resistance is not critical. The same preparation applies.
SPECIAL POINTS
Avoid painting in strong direct sunlight where possible. This increases the risk of the paint coating surface drying too fast, skinning with the subsequent formation of blisters, in addition, the “wet edge” is rapidly lost resulting in brush or roller marks.
Do not paint in dusty conditions, for example immediately after you have sanded off a surface. This will result in a rough finish.
Sounds obvious but paint in a systematic manner, start at one end and work to the other. Avoid breaks when in the middle of a large area and try to be consistent in brushing or rollering.
Do not apply the paint to thickly; stick to the coverage guide. Failure to do this can result in “solvent entrapment” in the paint film followed by blisters. Don’t be tempted to get full coverage in one thick coat.
Always observe the recommended overcoat times when using two pack products. Ensure the previous coat is dry before applying the next coat. Single pack air drying paints must be given time to dry. Failure to do this will cause blisters and a “cheesy” paint film.
Most conventional coatings cover 8-10 Square metres (this is a general guide)
The most obvious one – make sure the surface is clean and dry, that includes during and after application. Do not paint before dew forms or the sea mist arrives! The finish will “bloom” i.e. go cloudy in appearance as moisture becomes trapped in the paint. You’ll have to let it dry, sand it down and reapply (watch out for rain when using any two pack products).
Try to avoid contaminating your paint by using a separate container or “kettle”.
Wood is a natural material and whilst care should be taken with every surface, moisture can be a problem in timber. Ensure the surface is dry this can take a long time (i.e. weeks in some cases). Good ventilation and conditions are essential.