Alkyd Topcoats

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Technical Advisory Document TAD0015

Alkyd Topcoats Over FIRETEX

Alkyd topcoats can be used over FIRETEX thin film intumescent coatings with the following provisos:-

1. Subsequent re-decoration with further coats of alkyd may mean that in a fire situation, the coating may not be able to fully perform its intumescent properties due to a hard crust of alkyd over the top, thereby preventing full char development.
2. Minimum overcoating time with an alkyd topcoat is 24 hours to prevent solvent retention and possible wrinkling of the topcoat.
3. Prior to application of the alkyd topcoat, it is essential to ensure the correct thickness of intumescent has been applied as sandwich coating (FIRETEX/alkyd/FIRETEX/alkyd) will not be possible.
4. Most noticeably at low thicknesses of intu (up to 500 microns dft) there is the possibility of pinholing occurring in the alkyd topcoat.
5. For high thicknesses of intumescent, through drying of the system will be retarded once the alkyd topcoat has been applied.

It should be noted that the above concerns do not apply when using a topcoat such as FIRETEX M71V2 which regardless of number of coats will never form a hard crust in a fire situation, can be applied over the intumescent after 4 hours if required and can subsequently have more applied over the top, and does not significantly retard through drying.

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