when to seal windows

[umpire111]

am repainting my boat, not taking the windows out. Have cut back the old sealant around the windows but not sure when to put the new in. Do I do it before painting and then paint over it or seal after the final coat has gone on?

[Neil Smith]

Is the sealant what squeezed out when they were fitted or applied after.

 

Neil.

[forsberg]

Sealant first.

[blackrose]

Really? I thought it was paint first. Isn't that why professional boat painters take windows and fittings off so that they can paint the steel behind first before refitting and sealing them? I know the OP isn't removing windows but surely the same principal applies?

 

Also most of these supposed "overpaintable" PU sealants like Marineflex don't really like being painted.

Edited March 7, 2015 by blackrose

[blackrose]

am repainting my boat, not taking the windows out. Have cut back the old sealant around the windows but not sure when to put the new in. Do I do it before painting and then paint over it or seal after the final coat has gone on?

 

I guess the answer depends on how well you're prepping the surface under the sealant that you've removed. If it's being properly prepped and keyed, going back to bare steel in areas where there was any corrosion for example, then I think it should be primed, undercoated and painted first. Otherwise if you're not prepping it perhaps it doesn't matter which you do first, but then I wonder what the point of removing the sealant around the windows was in the first place....

 

What sealant are you using?

Edited March 7, 2015 by blackrose

[Higgs]

am repainting my boat, not taking the windows out. Have cut back the old sealant around the windows but not sure when to put the new in. Do I do it before painting and then paint over it or seal after the final coat has gone on?

 

 

When you say "put the new sealant in", are you thinking of taking the windows out at some point after the paint job or, are you thinking of sealing around the windows, without taking the windows out at any point?

 

If you have any rust around the windows it has, more than likely, spread from beneath the windows and windows out would be a good thing to do prior to painting. The surface under the window will need prepping and painting. If your windows aren't leaking, there's no need to seal beyond the window frame edge and trimming has only cleaned the edge back. If you have used a blade to trim the sealant back, are you sure you haven't cut through the old paint, down to the steel. Doesn't matter if you're stripping back to steel. If you're not going down that far, the cuts will lead to rusting at a latter date.

 

I used to double seal the windows, after the paint job. Fit them in on butyl, wait a few days, clean back to the window's edge, put a bevel of black rubber sealant around the windows to finish for sealing and cosmetic reasons. It is something I used to do because I found painting to the edge of window frames never produced the best looking or robust finish. Over time, painting cracks around where it has overlapped sealant and looks untidy. The rubber finish over the paint avoided the paint looking tired and added some extra sealant protection.

 

If you are planning to only reseal the edge, do this after painting

Edited March 7, 2015 by Higgs

[forsberg]

As not taking windows out I assume a touch-up job so no or minimal rust, sealant will bond well with sealant, with paint in between...

As for overpainting sealant very much depends on how long you let it harden and which paint you use.

I'm always to eager, sigh.

[The Bagdad Boatman (waits)]

If by cuttinng out the old sealant you have scratched through the paint to raw steel then you have a problem preventing rust.