What do I need... Gelcoat or Topcoat?

KevO

KevO

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I've got some dinks to repair in the stem of my Hustler. A previous owner had done a rough and ready job but now is the time to do it properly.

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Despite never having done this before I am nevertheless happy to have a crack at it. But now I come to the ordering of supplies... Do I want coloured gelcoat or coloured Topcoat? (I have used a RAL colour sheet to identify an acceptably close match). I intend to grind and sand it back to sound material where appropriate, then build up the surface by brushing on polyester in layers until it is all fair etc then polish in to match the rest of the topsides. Is one material easier to work with than the other and why? Is gelcoat or topcoat going to be more appropriate for my needs and intended method of application? :confused:
 
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Yes, cleaning out all that rubbish and making good with gel coat is the correct way. Topcoat is an International paint, not for repairing gel coats. You may well find you have to do some making good before you gel coat.
 
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Apologies if telling granny about eggs:
my understanding of flowcoat is slightly different, but it doesn't really matter.
Basic gelcoat will not cure unless isolated from the atmosphere: that's what the wax does.
So your choices: paint with waxed gelcoat after filling and fairing, then sand smooth and finish the gelcoat surface.
Or, apply gelcoat, then cover with something to exclude air to allow it to cure. Masking tape will suffice, although there are proprietary plastic membranes for this purpose which give a smoother finish. If carefully applied, the covering will help in approximating the gel to the desired contours. Then sand and finish as before.
 
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Thanks to all and especially Mac,... a clear confirmation of what I thought was correct but wanted to be sure about.
 
Flowcoat is basically gelcoat with the wax in it to allow it to cure on the surface in the presence of air. Perfectly fine for repairs imo and used it many a time with no ill effects. If you want to use gelcoat, the best way to exclude air and not disrupt the surface is to spray the gelcoat with PVA mold release. This excludes air to allow it to cure fully on the surface and is easily washed off.
 
G'day KevO,

I would use the flow coat, you are in for some sanding anyway, so make the application easy rather wrapping and getting wrinkles that need further filling.

get a good key on the base after filling and low areas and double check the colour match before you apply it, also a good idea to mask the area.

It's not rocket science mate, just a lot of rubbing down with finer and finer grades of wet n dry to get a mirror finish, almist forgot, all anding should be with blocks only, or your mirror finish will like a deformed mirror.

Good luck and fair winds. :)
 
Thanks again folks,

using flowcoat and thus avoiding having to seal it all off with sheeting when working off a ladder sounds attractive :D.

Ok... final question (I hope)...

Having ground out, keyed, filled and faired (with suitable marine filler) and wiped it down I paint on the flowcoat and let it cure. Having rubbed it back I find that I need to add another layer or 2. Can I do that or is flowcoat a one coat only job? :confused:
 
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Ok .... ballcox... now I see they sell pre-coloured gelcoat filler. Does that mean I can prep the area, fill the dinks/shallow areas and leave it slightly proud, sand it all back fair and then just polish without having to add anything else?

Sorry for the many questions... I just want to get it right with min fuss and expense and avoid duplication of effort. :p
 
davidej said:
what is that peel ply (???) or what ever they call it that is made to cover this type of repair?

Where do you get it?
Click to expand...

peel ply is used more for vacuum bagging. It's a special material although taffeta(sp) or rip stop nylon from the local haberdashery works just as good.

And Kev0 you can use multiple coats of flowcoat. The wax in it rises to the surface so if you wet sand you will remove most of it anyway. The rest can be cleaned off with acetone or MEK. To ease your fears, a lot of DIY fibreglass resins contain wax for the same reason flowcoat does and there's no issues doing multiple layers if reasonable precautions are taken.
 
ReefMagnet said:
peel ply is used more for vacuum bagging. It's a special material although taffeta(sp) or rip stop nylon from the local haberdashery works just as good.
Click to expand...

Macd mentions "proprietary plastic membranes" to cover a job like this to keep the repair in place and smooth it off while it cures.

If peel ply is not the stuff - and i know polythene is far from ideal- what should be used?
 
Peel ply will keep it smooth if it can be applied without scrunching or wrinkles in the first place. It's just a fabric with such a fine weave that any resin that soaks through will shear when the ply is pulled away from the job. Maybe that is what macd was referring to? Anything thicker won't conform to contours. When vacuum bagging you general use peel ply against the job, then a breather fabric then a plastic sheet to form the bag.

For this particular job, i'd just throw the flowcoat on and sand it off. Polyester isn't that difficult to sand. For a bigger job or to build up thin gelcoat, thinned with acetone and sprayed works very well.

For the mechanically minded it is possible to make a very nice vacuum machine on the cheap from an old fridge compressor, rubber dent puller and a few micro spray irrigation fittings. A deluxe model can also include a vacuum gauge, limit switch and dashpot. You can use vacuum for gelcoat repairs and it would be ideal for the op's repair and I suspect it would give good results with minimal sanding once cured.
 
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