Flowcoat problem

[Stemar]

Yesterday afternoon, I flowcoated the inside of my lazarette cover. It was a bit slow going off, and it was cold in my workshop overnight, but it's all gone off now apart from a patch a couple of inches square that's still wet.

My first thought was that it wasn't mixed properly, but I've used epoxy resin & polyester filler before and never had a problem, so I do know about the need to mix well, and am pretty sure I did.

Is there anything I can do to salvage the job and persuade this bit to go off - a drop of catalyst brushed into it, perhaps?

Also, what can I do to ensure I don't have the same problem when I do the outside, where the appearance will matter?

 

[fisherman]

I've had this happen for no apparent reason, black flocoat in the open it took days. Sometimes it depends whether the surface is horizontal or vertical, something to do with the styrene gas sitting on the job or not, I can't remember which. Apply gentle warmth, maybe a roving light/anglepoise? If that doesn't work I would brush over a bit more flocoat well catalysed.

 

[Bosun Higgs]

Yesterday afternoon, I flowcoated the inside of my lazarette cover. It was a bit slow going off, and it was cold in my workshop overnight, but it's all gone off now apart from a patch a couple of inches square that's still wet.

My first thought was that it wasn't mixed properly, but I've used epoxy resin & polyester filler before and never had a problem, so I do know about the need to mix well, and am pretty sure I did.

Is there anything I can do to salvage the job and persuade this bit to go off - a drop of catalyst brushed into it, perhaps?

Also, what can I do to ensure I don't have the same problem when I do the outside, where the appearance will matter?

becuase the ratio of catalyst is so small with polyester, it really is difficult to get a 100% thorough mix. I'd be inclined to wipe it off with acetone and redo that bit - it being flowcoat inplies it isnt really a cosmetic job.

 

[HunterWanderer]

Its probably condensation as water prevents the catalyst acting. Try a hot air gun or hairdryer to raise the temperature such that the water can evaporate then the catalyst will start to cure. If there is water trapped under the flowcoat it will take a long time but will eventually cure. If you can't wait remove with acetone soaked paper towels.

 

[fisherman]

I once applied a sacrificial patch to the hull, and found I had used one tenth of the normal catalyst, between 0.1 and 0.2%. I scraped the work off and chucked it in a bin. At the end of the day it had gone off perfectly well, although it probably would not have bonded very well on the job. Incidentally, the patch was applied to the hull between tides as a temporary measure: 12 years of dragging thousands of pots across it and it's still there.

 

[Stemar]

Thanks everyone. I've tried warming it and it hasn't made any difference, so I've ordered some acteone and will have another go this weekend.

BTW, where it has gone off OK, it's a flat finish. Is that normal? If so, would it polish up to a reasonable shine or is flowcoat not suitable for stuff that's on view?

 

[PirateMark]

Flow coat is intended to be the top layer, hence why the wax is mixed with the gel cost ie finishing coat, a good rub down with wet and dry starting at 1200 grit up to 3000 then a good rubbing compound with give you a good shine, normal gel coat with no added wax will always stay tacky ready for a top coat or flow coat.

 

[sailorman]

Whats wrong with simple bilge/locker paint

 

[Quandary]

All the non visible internal surfaces in our boat (Finngulf) are flowcoated; the hull, inside of lockers, bulkheads. locker lids and floors. bilges etc. White generally, but brown in bilges below floor, underside of floorboards etc. It is an even satin matt finish with roller texture, extremely tough and durable but easy to scrub and the all white locker interiors make stuff easy to find, no chips or bare spots anywhere after 5 years of use, not even in the anchor locker.
Perhaps a bit harder to apply but looks as if it will last the boats lifetime. Recommended.

 

[Stemar]

Whats wrong with simple bilge/locker paint

Nothing, but I was given 5 litres of flowcoat + the hardener a couple of years ago and it seemed like a good way to use it. It does seem as though it probably wouldn't be the best finish where it's on display, though. I need to redo the insides of a couple of lockers, so I think I'll use it in them and use paint for the bits that are on display.

 

[basil421]

BTW, where it has gone off OK, it's a flat finish. Is that normal? If so, would it polish up to a reasonable shine or is flowcoat not suitable for stuff that's on view?

Flow coat is basically a gel coat with a wax solution added to ensure a good surface cure. Surfaces exposed to air are inhibited from curing and the wax solution solves this by migrating to the surface and forming a film which excludes air allowing the surface to cure. The wax layer is mat in appearance but can be flatted back and polished to a good gloss using compounds.

The fact that an area has not cured could be due to:
a. poor mixing of the catalyst
b. styrene being trapped above the surface (this usually occurs in a deep recess such as the skeg in a hull moulding or similar)
c. very low temperature during the curing period.
To check the rest of the job is not suspect so I would recommend you try a test on a small area of the cured flow coat before applying the repair coat. Test by cutting back with 320 grit wet and dry paper, used wet and ensure the paper is not blocking. If the paper blocks the cure is suspect and the whole area may have to be removed and re-done.
I hope this is not the case as it's an awful job to do

Good luck
Basil

 

[nigelmercier]

Thanks everyone. I've tried warming it and it hasn't made any difference, so I've ordered some acteone and will have another go this weekend...

How long did you warm it for, minutes or hours? A fan heater overnight on a low heat setting is best, the airflow is as important as the heat.

 

[Quandary]

Nothing, but I was given 5 litres of flowcoat + the hardener a couple of years ago and it seemed like a good way to use it. It does seem as though it probably wouldn't be the best finish where it's on display, though. I need to redo the insides of a couple of lockers, so I think I'll use it in them and use paint for the bits that are on display.

There might be a clue to the problem here, most of these two pack resin products have a shelf life, (though I have used stuff a couple of years older without a problem). However, if the OP is like me, stuff I have had for 'a couple of years' can turn out to be up to ten years old.