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Painting with Two-Part Perfection - Interlux

Step 1: getting ready

Two-part polyurethanes are tough but sensitive beasts.

  • The curing agent, a clear liquid in a separate can, has to be mixed at the precise ratio to set the paint off.
  • High humidity (over 70%) could cause 'blooming' which is a loss of gloss surface.
  • The paint ideally needs to go on at 15-20CDeg (59-68Deg F)
  • Preparation is the key. Previously, we had:

  • Sanded the hull
  • Faired all the gouges with epoxy filler
  • Applied two coats of undercoat to give depth of colour and to avoid patchiness in the topcoat
  • Flatted back the final undercoat and then washed the hull down to remove all the dust
  • As our boat was staying blue, we used a blue undercoat - but had we changed to a lighter colour, two coats of white would have been used instead.

    1. All of the areas to be painted must be instantly accessible. You need to be able to keep moving and don't want to waste time repositioning ladders. If a wet edge of the paint goes hard, it will leave a visible ridge.

    2. Have all your tools to hand. Make sure you have enough paint trays, enough paint, and spare rollers and tipping brushes ready to go.

    3. Down with dust! Saturate the area around the boat with water to stop any dust rising, and try to pick a day when there's no wind.

    4. Check the masking, as tape can be dislodged or damaged during the painting or curing times, so just check it's all still in place.

    5. Give the gunwale a wipe with tissue just to ensure that all residual moisture from the wash-down has been removed.

    6. Wipe any dust or grease from the paint trays using thinners.

    Top tips

  • A quality finish needs quality tools. We used a 3in 'Fine Finish' nylon tipping brush, and 'Fine Finish' decorators' rollers. We found the cheaper ones from some DIY outlets tended to break up after a short time.
  • Only touch the hull while wearing gloves. Sweat and oils on your skin can be transferred to the hull, which can affect the paint.

  • Step 2: mixing the paint

    1. Open both cans and stir the base paint thoroughly as the contents settle with storage. Always use a clean stirrer. A flat, ruler-type stick works best.

    2. Add the curing agent. The tins of base colour are deliberately only two thirds full, so you can tip the entire curing agent into the main tin for the right ratio. For smaller amounts, use a measuring cup which has the ratios marked on the side. Stir well and in a random pattern. The curing agent has to be thoroughly mixed with the base.

    3. Decant the amount of paint you think you'll need into a measuring cup (you'll have discovered from the undercoating stage how far the paint will go, and can become quite accurate). Add between 5-10% thinners depending on how warm the day is - the warmer the day, the more thinners. We used a ratio of about 8% thinners.

    4. Again, stir well. Lifting the stirrer out and letting the paint fall back in will show how consistent the mix is.

    5. To minimise the chances of dust settling on the hull, give it a final wipe with a tack-rag just as you are about to paint. The tack-rags contain a wax, so only wipe them gently over the hull. Put on too much pressure, and the wax is transferred to the glassfibre, which could interfere with the finish.

    6. Pour enough paint into the paint tray so it reaches to the edge of the incline. Dip in the tipping brush so the ends are pre-primed, and load up the roller. Move everything you need close to the hull.

    Top tips

  • Some tin lids have a double lip. Try to make sure you've inserted the lid remover under the uppermost lip, and not the second one. If the lid is putting up a fight, this may be the reason.
  • Pour paint into the measuring cup carefully. If it slops it will obscure the graduation marks for the thinners.
  • Cover over the tin when leaving it for any time, just in case a seagull decides to add to the formula. Although activated, the paint will stay workable for a long time in its tin.

  • Step 3: applying the paint

    'Don't be afraid of it,' Richard Jerram advises. 'It's only paint.' His secret is to be bold and confident with the brush, using a series of strokes, diagonally, and then finishing with a downward 'tipping off' motion.

    1. If you're right handed, start from the right. Begin at a hard edge, ie the bow, and be prepared to end at a hard edge - the transom. You won't be able to stop for more than a minute or so along the hull, or the wet edge of the paint could dry.

    2. Roll the paint on by driving the roller in several directions for an even coverage.

    3. Now work the tipping brush across the paint, diagonally at first, and then finishing with downward strokes. The idea is to remove all the 'orange peel' effect from the roller.

    4. Start the next area a few inches beyond the wet edge, and work back to it. This allows the roller to empty some of the paint before it hits the wet edge again, and gives a more even coverage.

    5. Work the tipping brush right across the area, especially over the seam between the panels of paint. Finish off again with the downward strokes.

    6. Keep going, rolling vigorously, and then quickly tipping off. Note how Richard is holding the brush, using all his fingers for greater control.

    7. If you need a comfort break, stop at a natural junction. You may decide to call a halt here and start again a following day. The bow and quarters form a natural break line, and some hulls will have other places you can stop. If you decide to keep painting, the tipping brush can be used to merge the paint seamlessly around the corner.

    8. By the time we had done one side of the 21-footer, which only took Richard about 30 minutes, it was time to change rollers, as the first one was starting to soften and lose its shape.

    Top tips

  • Don't use paint pads! International's Perfection has been formulated for use with a brush and roller. The solvents tend to cause paint pads to shed hairs in alarming amounts.
  • If an insect lands in your gloss coat, leave it alone. You can extract it once the paint has dried. 'If it looks like it might move, pick it out,' Richard advises. 'You don't want it walking across your work.'
  • The best way to remove the old roller is simply to knock the shaft against a suitable post. The roller will fly off, saving messy fingers.

  • Step 4: cleaning up

    Unfortunately, there can be a lot of wastage with two-part paints. Unused activated paint is simply allowed to go hard before being binned - it can't be poured back and reused like ordinary paint. Rollers are also deemed one-use. Brushes, however, can be thoroughly cleaned out with solvent, (it has to be the right solvent, such as Thinners No9) and then washed in warm, soapy water before being allowed to dry. Masking tape should be removed as soon as possible, and is one of the satisfactions of the job. Solvent can be disposed off at the yard's solvent bin.

    The gloss coat should be left until the next day before being wiped over with a Scotchbrite scouring pad, and then recoated. There is no variation in the thinner ratios or mix, and the second coat will add extra depth to the first.

    If the job has been left for a while, the topcoat will need a gentle rub down with 400-grit (perhaps 280-grit to flat off any runs) before recoating.

    International advises that the final gloss coat is left unmolested for about six days for it to fully harden, so avoid having the boat lifted or moved until then.

    Et voila! Although our rubbing down of the undercoat hadn't been quite up to Richard's standards, he achieved a superb finish in a very short time. We used about 500ml of paint for one coat on the 6.4m (21ft) hull, and she looks great. The 80-micron layer of gloss will cure back to just 40 microns, which is why a second coat is recommended.

    Obviously, a lot of time was spent in the preparation, but when you see the results sparkling in the sunshine, you sort of forget about all that.

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    Topside Paint FAQ
    Refinishing NonSkid
    Three Options to Painting Non-Skid
    Topside Paint Selector
    Two-Part Perfection Preparation Scheme
    One-Part Paint Preparation Scheme
    Preparation and Priming for Topside Paint
    Applying Gloss Finish
    Fill Holes, Voids and Nicks
    Painting with Toplac
    Painting with Two-Part Perfection
    Tips on Applying Perfection
    Painting Bilges
    Do's and Don'ts for Paint Finishes

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