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Sealing Areas Exposed to UV Radiation

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					Marine Application Guide




        5.8 Sealing Areas Exposed to UV Radiation




        Application Description
        On modern ships, yachts and motor boats the        Conventional polyurethane sealants, however,         Sikaflex®-295 UV, available in either white or
        joints between different materials must be         exhibit some sensitivity to UV radiation. After      black, provides excellent resistance against
        sealed for water-proofing, corrosion, etc. But     prolonged periods of exposure the joint may          solar UV radiation and seawater attack, the
        they must also supply an aesthetic finish to the   show fine cracks and degradation at the surface.     white grade also has superior non-yellowing
        joint.                                             This does not affect the sealing properties, as it   characteristics.
        High-performance sealant joints can be             is only a surface blemish. If a durable surface      Sikaflex®-295 UV is therefore particularly suited
        made with conventional one-component,              aspect is required, a specifically formulated, UV-   for sealing such areas as deck fittings, hatches
        polyurethane-based systems, which, due to          resistant polyurethane should be used.               and window rebates.
        their excellent adhesion to various substrates,    Most vessels and in particular, luxury yachts,
        allow permanent elasticity and resistance          require a large number of such joints and hence
        against water ingress and corrosion.               require the use of a high-durability sealant.




                                                                                                                                                 74_Sika Transportation
                                                                                                                                                           Marine Application Guide




Performing UV-Resistant Sealing
Applications
Substrate Preparation
Wood                                                       GRP                                                        Applying Sikaflex®-295 UV Adhesive

             Abrade the contact area on the hull with a                Lightly abrade the contact area with a very           Mask the surrounding area before priming
             sanding pad (80/100 grit)                                 fine sanding pad                                      and sealing


             Remove the dust with a vacuum cleaner                     Remove the dust with a vacuum cleaner                 Sikaflex®-295 UV should be applied to the
                                                                                                                             joint in a bead of the required dimensions
                                                                                                                       295   taking care to avoid air entrapment
        Apply a thin continuous coat of Sika®                          Pretreat the substrate with Sika® Aktivator,    UV
        Primer using a clean brush or a felt                           using a clean, lint-free rag or a paper
                                                                       towel. Change the rag frequently!                     Use a plastic spatula to remove excess
 290 DC applicator. Use Sika Primer-290 DC LOT
                            ®
                                                           Aktivator
        for teak and use Sika® Primer-215 for                                                                                sealant squeezed out around the edges.
  LOT
 or 215 other wood                                                                                                      N    Tool to a smooth finish within the tack-free
                                                                       Flash-off: 10 minutes (min) to 2 hours
                                                                                                                             time of the sealant using Sika® Tooling
                                                                       (max)
                                                                                                                             Agent N
             Drying times:
             Sika® Primer-290 DC LOT - 30 minutes
             (min) to 3 months (max)                                   Apply a thin, continuous coat of Sika®                Uncured Sika adhesives or sealants may
             Sika® Primer-215 - 30 minutes (min) to 24                 Primer-206 G+P or Sika® Primer-215,                   be removed with Sika® Remover-208 and
             hours (max)                                     206       using a clean brush or a felt applicator        208   remove the masking tape
                                                             G+P
                                                             215                                                             Do not use Sika® Aktivator or any other
Aluminium and Stainless Steel                                                                                                cleaning agent or solvent for cleaning
                                                                       Drying time: 30 minutes (min) to 24 hours             purposes
                                                                       (max)
             Pretreat the substrate with Sika Aktivator,
                                            ®
                                                                                                                             For bonding transparent substrate please
             using a clean, lint-free rag or a paper                                                                         refer to Section 6.7 and 6.8
             towel. Change the rag frequently!
 Aktivator
                                                           Acrylic and Polyurethane-Based Paint                              Please consult Sika Technical Service
             Flash-off: 10 minutes (min) to 2 hours                                                                          Department if joints are prone to high
             (max)                                                     Pretreat the substrate with Sika® Aktivator,          dynamic stresses
                                                                       using a clean, lint-free rag or a paper
                                                                       towel. Change rag frequently!
                                                           Aktivator


                                                                       Flash-off: minimum 10 minutes, maximum
                                                                       2 hours


                                                           For the preparation of other substrates, please
                                                           refer to the Pretreatment Chart for Sika Marine
                                                           Applications on page 146-147 or contact your
                                                           local Sika organisation.




Sika Transportation_75

				
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posted:11/2/2011
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