How to fully repaint steel / cast iron
Paint Guide BW068
Paint job at a glance
Here's your custom paint guide
Before any project, take these things into account to get the best results:
- Factor in enough time for each stage of your project so you don't have to rush.
- Always check the weather while planning your project. Temperature, humidity and dew point affect the quality of your work.
- Check you have all the equipment, tools and products you need.
- Ensure you read all the information in the health and safety tab above.
Equipment we recommend for this guide
Your health and safety
Your safety is of the utmost importance to us. Ensure that you read and follow all label instructions and the safety datasheet before starting your project. Also:
Ensure the area you are working in is properly ventilated.
Ensure all products are kept out of reach of children during storage and usage.
Ensure solvent fumes and any splashing of material will not affect others nearby.
PPE (Personal Protective Equipment)
Before you begin, always refer to the label and safety datasheet for product specific information. Using the right PPE for your project is important to ensure your safety. You should always check the information from the PPE manufacturer to ensure you use the correct items for your working conditions.
Wear safety glasses at all times to protect your eyes from splashes.
Chemicals can cause skin irritation. Wear overalls and protective gloves to protect your skin and clothing.
To avoid inhalation of dust while sanding; wear a dust mask at all times.
Many products contain either solvents or other chemicals that can build up in confined areas creating a hazard and/or an unpleasant working environment. Wear suitable respiratory protection if ventilation is not sufficient or if required by the safety datasheet to do so.
See the protective equipment overview for further information.
We care deeply about the environment and we want to ensure that our products are disposed of in the correct way. With that in mind, please:
- Always refer to the product label and safety datasheet for any specific instructions.
- Ensure any waste product including cans, rags, brushes, roller sleeves masking tape and paper, gloves and overalls are disposed of according to local regulations.
- Do not allow any waste material such as unused paint to enter any waterways.
- Ensure waste and empty containers are disposed of in accordance with local legislation guidelines and national regulations.
For more information or any special waste regulations, please contact your local waste regulation authority.
Step 1 Cleaning painted steel / cast iron
1.1 Rinse
- Rinse the surface with fresh water to remove loose dirt, growth or any other contamination. You can also scrub it with a hard sponge.
- To tell if the surface is properly degreased, the water should spread across the surface while flushing. Small droplets of water are an indicator that the surface isn’t fully degreased. If so, repeat the cleaning process.
- Never clean antifouling with solvents as this can damage the surface.
- High pressure washing removes most of the growth in an effective way.
- Pay attention on the distance between the surface and the high pressure washer. Some machines have enough power to remove the paint system.
- Special attention should be paid to clean around the waterline or other areas with visible contamination using an abrasive pad with water.
- High pressure washer
- Extension for cleaning tool
- Sponge and/or cloths
- Rubber gloves
- Safety shoes
- Overalls
- Eye protection
- Specialized cleaning product
Step 2 Sanding painted antifouling in good condition
If the new antifouling is compatible with the existing one, you can normally apply it directly on top of the old one without sanding. If this is the case, please go straight to application of antifouling after following the washing / cleaning procedure. However, if the existing antifouling is not compatible with the new one, you will need to apply a barrier primer after a light wet sand.
Please be aware that antifouling must only be wet sanded to minimise exposure to biocides.
2.1 High pressure water wash or light wet sand
- High pressure water wash using scrapers or 80 grit wet sanding on areas that have difficult to remove fouling such as shell growth bases.
If high pressure water washing is not possible/available.
- Wet sand the whole area with 80 grit to ensure the surface is thoroughly clean and free from all fouling residues.
2.2 Rinse
- Rinse surface with fresh water.
- Allow to dry.
- For a longer life expectancy of the paint scheme you could light wet sand with 120 grit to remove the surface layer of the old antifouling (the leach layer). This will decrease the risk for future detachment problems.
- Even if the antifouling is compatible, we recommend a light wet sand around the waterline to ensure the best adhesion in this area.
- Sanding paper 120 grit (various grades for surface preparation)
- Cleaning thinner
- Rubber gloves
- Dust mask
- Overalls
- Eye protection
Step 3 Applying antifouling paint
3.1 Mask off
- Mask off any areas that are not going to be painted such as topsides on the waterline with suitable masking tape.
3.2 Mixing
- Single pack products:
- With single pack antifoulings mix the paint thoroughly with a stirring stick ensuring that any settlement is well mixed in. Stir frequently during application as the heavy compounds may settle during use.
- With single pack antifoulings mix the paint thoroughly with a stirring stick ensuring that any settlement is well mixed in. Stir frequently during application as the heavy compounds may settle during use.
- Two pack products:
- If you are using a 2 pack antifouling, mix the individual components thoroughly (if both are liquid). For some products the second component can be a powder.
- Combine the two components and mix the paint thoroughly as indicated on the datasheet or the can.
- If you are using a 2 pack antifouling, mix the individual components thoroughly (if both are liquid). For some products the second component can be a powder.
3.3 Application
- Antifouling paints are formulated to be applied as they are, so there’s no need to add thinners to them. However, there are some occasions where a small amount of solvent can be added to aid application. Diluting the antifouling too much will affect the amount of product that's applied to the surface and in turn its long term performance. Please see tips for more details.
- Pour the paint into a clean roller tray.
- Roll or brush the paint onto the surface ensuring that a good even film of paint is applied. For additional information related to your specific product, please refer to the datasheet, the label on the can or further information on this website.
- Allow the paint to dry as per datasheet or label on the can.
3.4 Overcoating
- Most products will require more than one application or coat as per datasheet or label on the can.
- If additional coats are required follow the recommended overcoating times as per the datasheet or label on the can.
- It is good practise to apply an extra coat to leading and trailing edges such as the waterline, trim tabs, outdrives, keels and rudders. These areas experience more water flow and turbulence and hence more wear on the paint surface.
3.5 Finishing up
- Be sure to follow immersion times carefully. If you don’t, it could result in the detachment, blistering or cracking of the antifouling. The marine environment is harsh so the paint must be allowed to dry thoroughly before immersion.
- Once the paint is dry, remove all masking tape.
- To clean equipment, use the recommended solvent from the datasheet or the label on the can.
- For waste disposal please refer to the top of this guide.
Working with a roller:
- Applying paint with a roller is a fast method of covering large areas.
- For most antifoulings applications a 7-9 mm nap solvent resistant mohair roller is suitable. For thinner antifoulings, a 5-6 mm nap solvent resistant mohair roller, or a high density closed cell foam roller should be used.
- If rollering with felt or mohair rollers, wrap masking tape around a new roller and then pull off to remove any loose fibres.
- Some rollers may be affected by solvents in the product and can swell during use. When they become too soft to use, or look like they are breaking up, replace them with a new one.
- When using a roller and tray it is a good idea to keep the tray covered loosely to avoid the wind, sun or air creating a skin over the paint during use.
Working with a brush:
- Brushes are best used for small areas. As the finish achieved is unlikely to be as good as a topside finish, the type of brush you use isn’t so critical.
- Wash your brushes with the thinner and dry them thoroughly before use to avoid contamination.
Other useful tips:
- If it is particularly hot or cold weather conditions, you can add a small amount of suitable thinner (no more than 10%) to help ease the application. Check labels and data sheets to ensure that the correct thinners are used as some antifouling products are water based.
- Never add anything else (additives, etc.) to an antifouling as this won’t improve performance of your coating. It may adversely affect the chemistry of the paint formulation. In many regions or countries it is also illegal to do this.
- Do not mix different antifoulings because they could be based on a different chemistry and may impact performance.
- Don't leave masking tape on longer than needed as it will be difficult to remove.
- Ensure you apply the correct amount of paint as stated in the datasheet.
- Solvent mask
- Paint rollers (suitable sizes and types)
- Paint brushes (suitable size)
- Safety shoes
- Hand protection (as per product SDS)
- Overalls
- Eye protection
We're here to help
We're ready to help. Our friendly help desk is open weekdays 8:00 - 16:30
Call 01489 775062
Send an e-mail to iyp.uk@akzonobel.com
Whether you call or e-mail, please mention your paint guide reference: BW068