Енциклопедія яхт
Barrier coat cycle
The word barrier does not name one coat count. West System sheets and Gelshield 200 print different dry-film numbers, and this page does not collapse them.
In the West System sheet on blisters, a barrier is at least 20 mil of epoxy, usually five or six coats. The first coat has no additives. The others take additive 422. The sheet allows up to ten coats, but it says the extra coats do more for a boat that has already blistered in warm water than for a boat in cold water with no sign of hydrolysis. In the same maker's manual, the September 2021 file, osmosis repair is given as six coats or about 600 microns. On these pages 20 mil and 600 microns are not one number. They must not be collapsed.
What it is
A barrier-coat cycle is the planned application of epoxy barrier coats, often after sanding or after the old coating has been taken off, before antifouling goes back on. One coat and a fresh colour on top is not yet a cycle.
On the short West System instruction, two coats are called enough as a moisture barrier, three if the surface will then be sanded, and protection grows to six coats or about 20 mil. Two coats are not the repair the blister sheet is talking about. The distributor Wessex Resins repeats six coats or about 600 microns and writes that there is no hundred-percent success for years ahead: a return is possible. Before the work they advise asking a surveyor. These texts do not guarantee "dry forever". A wet laminate core is not cured with barrier paint: that is a moisture strategy, not a substitute for a core repair.
On International Gelshield 200, in the sheet whose file name is 20241126, the minimum is five coats by brush and 250 microns of dry film, 50 microns a coat. Grey and green alternate, and the job starts and ends with grey. In the bilge, only two coats. That sheet forbids laying the product over single-pack paints. Old antifouling is often single-pack. A fresh colour on top does not show that. An earlier how-to from the same brand already speaks of six coats, the first one green, and at 23 degrees gives a window of 3 to 7 hours in which to get the first antifouling coat on. That window belongs to that how-to. It is not glued to the five-coat sheet.
On an invoice it is useful to see the product name, the number of coats and the dry thickness, and, separately, whether the old single-pack paint was removed. The words "barrier done" are not enough for that. This page does not choose one thickness from 20 mil, 600 microns and 250 microns. Nearby on the site: epoxy barrier coat, antifouling, blistering, survey checklist and the osmosis article are other pages, not this invoice.