HELP....... Polyester Flow Coat

[lloydlloyd]

HELP!

Has any one ever put flow coat, onto flow coat.

Basically we put the flow coat onto the boat, and it was applied incorrect. Because it went on to thin in many places, so when we sanded it down we started going all the way through, until we reached the fibre glass.
Now the problem is is the flow coat has wax in it, and as far as we are aware nothing will stick to it.

Please some one share a miracle that will allow us to re apply a new coat of flow coat over a newly laid patchy thin layer of already sanded flow coat. (done on grit 80 to get rid of the high spots)
As we are presuming the two won't bond very well if at all and will flake apart either over time or very soon.
Many Thanks

 

[matt1]

HELP!

Has any one ever put flow coat, onto flow coat.

Basically we put the flow coat onto the boat, and it was applied incorrect. Because it went on to thin in many places, so when we sanded it down we started going all the way through, until we reached the fibre glass.
Now the problem is is the flow coat has wax in it, and as far as we are aware nothing will stick to it.

Please some one share a miracle that will allow us to re apply a new coat of flow coat over a newly laid patchy thin layer of already sanded flow coat. (done on grit 80 to get rid of the high spots)
As we are presuming the two won't bond very well if at all and will flake apart either over time or very soon.
Many Thanks

I just abraded then a quick wipe with acetone and then applied the new flowcoat

still good 13 yrs later

 

[steveeasy]

As stated above the wax sits on the top .it is perfectly normal to recoat by light sanding and wipe to build up layers.
Steveeasy

 

[Keith 66]

As above degrease with acetone, then sand it, degrease again & apply second coat.

 

[dankilb]

I’ve often wondered, though, if the plan or intention is to build up layers (as it often is), wouldn’t it be best to save the flowcoat for the final coat only?

In other words, build up with regular gelcoat, then use a flowcoat layer as you might with PVA etc to seal and cure the lot at the end?

(Obviously the OP didn’t intend for multiple coats here...)

 

[lloydlloyd]

As stated above the wax sits on the top .it is perfectly normal to recoat by light sanding and wipe to build up layers.
Steveeasy

Actually the wax seems to sit all the way through.
As we are aware of it coming to the surface, so gave it a test sand with wet and dry on one of the thickest parts after sanding. and found it coming to the same smooth wax finish.

 

[lloydlloyd]

I just abraded then a quick wipe with acetone and then applied the new flowcoat

still good 13 yrs later

Thank you

 

[lloydlloyd]

I’ve often wondered, though, if the plan or intention is to build up layers (as it often is), wouldn’t it be best to save the flowcoat for the final coat only?

In other words, build up with regular gelcoat, then use a flowcoat layer as you might with PVA etc to seal and cure the lot at the end?

(Obviously the OP didn’t intend for multiple coats here...)

I don't understand why one would build up layers with flow coat, its a finishing product is it not.
are aim was to put on one thick coat and then sand down.
But being are first time with the product and applying it onto a 24ft boat,
We had issues with it going of faster than we would have liked plus my rushed rubbish applying skills onto the boat.

 

[dankilb]

I don't understand why one would build up layers with flow coat, its a finishing product is it not.
are aim was to put on one thick coat and then sand down.
But being are first time with the product and applying it onto a 24ft boat,
We had issues with it going of faster than we would have liked plus my rushed rubbish applying skills onto the boat.

Yes - basically just as you’ve described - that it can be harder in practice to build up a thick enough layer to achieve the required finish, before it starts to cure.

Whereas my understanding is that normal gelcoat will stick to itself, like a laminating resin, as it doesn’t fully cure.

What I should have said is the intention is to lay on a thick coat (not necessarily more than one coat/layer) - but at least in my case, my technique isn’t up to it!

 

[PaulRainbow]

I don't understand why one would build up layers with flow coat, its a finishing product is it not.
are aim was to put on one thick coat and then sand down.
But being are first time with the product and applying it onto a 24ft boat,
We had issues with it going of faster than we would have liked plus my rushed rubbish applying skills onto the boat.

One builds up layers of gelcoat and/or flowcoat, because if one tried to do it in one thick coat, one ends up with a nasty mess that one has to sand off and start again

Best bet is to apply a coat in the same way that you would a coat of gloss paint.

De-grease then lightly sand before applying subsequent coats. When you get the last coat on and sanded to remove brush marks, sand with very fine wet and dry, down to 1000 grit, then polish with compound and finally wax it. It'll look like new.

You can use gelcoat for the initial layers, as Dan suggested, but you would need to cover the gelcoat or it will not dry properly, so you cannot sand between coats. You can use gel coat for all layers, even the final one, if it's covered. Cover with cling film, peel ply or, i use 2" wide clear packing tape for small repairs.

 

[dankilb]

To add - the best ‘technique’ I’ve seen is Andy on the BoatWorks YT channel who brushes on regular gelcoat in layers, wet-on-tacky, until he’s happy with the finish/opacity. Then he sprays the lot with PVA using a compressor!

Works great if you’ve got a workshop/spray kit! But it sounds like in theory a final layer of wax-in flowcoat coat could achieve the same (sealing to allow a final cure)?

 

[lloydlloyd]

One builds up layers of gelcoat and/or flowcoat, because if one tried to do it in one thick coat, one ends up with a nasty mess that one has to sand off and start again

Best bet is to apply a coat in the same way that you would a coat of gloss paint.

De-grease then lightly sand before applying subsequent coats. When you get the last coat on and sanded to remove brush marks, sand with very fine wet and dry, down to 1000 grit, then polish with compound and finally wax it. It'll look like new.

You can use gelcoat for the initial layers, as Dan suggested, but you would need to cover the gelcoat or it will not dry properly, so you cannot sand between coats. You can use gel coat for all layers, even the final one, if it's covered. Cover with cling film, peel ply or, i use 2" wide clear packing tape for small repairs.

This made me laugh and cry, as we are currently in this situation. we are looking at 4 days for two of us to sand it all back down to a smooth surface (live and learn)

So flow coat (not gel coat) will stick to itself after it has cured with a light sanding?

 

[lloydlloyd]

To add - the best ‘technique’ I’ve seen is Andy on the BoatWorks YT channel who brushes on regular gelcoat in layers, wet-on-tacky, until he’s happy with the finish/opacity. Then he sprays the lot with PVA using a compressor!

Works great if you’ve got a workshop/spray kit! But it sounds like in theory a final layer of wax-in flowcoat coat could achieve the same (sealing to allow a final cure)?

When I get a chance to build another boat, I will defiantly consider spraying the layers on.

 

[PaulRainbow]

This made me laugh and cry, as we are currently in this situation. we are looking at 4 days for two of us to sand it all back down to a smooth surface (live and learn)

So flow coat (not gel coat) will stick to itself after it has cured with a light sanding?

Flowcoat is gelcoat, with added wax. Gelcoat will not dry if exposed to air, so you have to cover it with something, the wax in flowcoat comes to the surface and excludes the air, allowing it to dry.

So, you can go wet on wet (partially cured) with gelcoat, using flowcoat as the final coat (or cover it), no sanding between unless you cover each coat.

Or you can use flowcoat and sand between, but you must first de-grease it to remove the wax.

For best adhesion between coats, allow to dry (in the case of flowcoat), but not fully cure.

 

[lloydlloyd]

Flowcoat is gelcoat, with added wax. Gelcoat will not dry if exposed to air, so you have to cover it with something, the wax in flowcoat comes to the surface and excludes the air, allowing it to dry.

So, you can go wet on wet (partially cured) with gelcoat, using flowcoat as the final coat (or cover it), no sanding between unless you cover each coat.

Or you can use flowcoat and sand between, but you must first de-grease it to remove the was.

For best adhesion between coats, allow to dry (in the case of flowcoat), but not fully cure.

Thanks for the reply,
But we have been told differently from the company called east coast fibre glass supplies. (FAQs

Their words are
"Flowcoat is not designed for high end aesthetic paint like finishes and second coats will not bond due to the wax content, any second layer applied no matter how well the first coat it is abraded, will most likely eventually start to flake and peel especially if the part is exposed to the outdoor elements."

Are thinking is its better to spend time sanding it all now, why we are here. Than to have to redo the work in how ever many years time it takes to slowly come apart.
At least we can guarantee a proper bond by sanding it all back down. Because the waiting for it to fail will be worse + it won't feel like a proper job
A lesson learnt the hard way, is a lesson better understood
At least I won't do it again. and can take this experience and apply it to other things in life....................

 

[PaulRainbow]

Thanks for the reply,
But we have been told differently from the company called east coast fibre glass supplies. (FAQs

Their words are
"Flowcoat is not designed for high end aesthetic paint like finishes and second coats will not bond due to the wax content, any second layer applied no matter how well the first coat it is abraded, will most likely eventually start to flake and peel especially if the part is exposed to the outdoor elements."

Are thinking is its better to spend time sanding it all now, why we are here. Than to have to redo the work in how ever many years time it takes to slowly come apart.
At least we can guarantee a proper bond by sanding it all back down. Because the waiting for it to fail will be worse + it won't feel like a proper job
A lesson learnt the hard way, is a lesson better understood
At least I won't do it again. and can take this experience and apply it to other things in life....................

So what's the plan now ?

What are you going to do when you've sanded it all off ?

 

[Trident]

If you do as advised and acetone, sand and redo it will be fine. You cant really feel the wax - it rises to the surface and eventually "evaporates" off

If you choose to sand it off then just go mad with 40 grit on a grinder and get it gone quickly and easily - you don't need to treat it with kid gloves.

I sort of do this for a living and always just use gel coat to build up multiple layers , wet on tacky or wet on dry, it makes no odds really if you don't have the time to wait for it to tack off and need to come back another day. The las coat of gelcoat gets a little wax additive to finish it off so it goes off fully. Then send it back (I start with 240 then 320, 400, 800 then polish) .

Just remember that its infinitely redo-able and renewable so you don't need to be too worried about doing it.

 

[lloydlloyd]

So what's the plan now ?

What are you going to do when you've sanded it all off ?

We are taking it back to the fibre glass epoxy layer and then re applying again.
But this time using a roller and having a extra helping hand to mix.
As last time my dad mixed and i applied using a paint brush
But this time we will both apply so I wont have to rush like last time

 

[lloydlloyd]

If you do as advised and acetone, sand and redo it will be fine. You cant really feel the wax - it rises to the surface and eventually "evaporates" off

If you choose to sand it off then just go mad with 40 grit on a grinder and get it gone quickly and easily - you don't need to treat it with kid gloves.

I sort of do this for a living and always just use gel coat to build up multiple layers , wet on tacky or wet on dry, it makes no odds really if you don't have the time to wait for it to tack off and need to come back another day. The las coat of gelcoat gets a little wax additive to finish it off so it goes off fully. Then send it back (I start with 240 then 320, 400, 800 then polish) .

Just remember that its infinitely redo-able and renewable so you don't need to be too worried about doing it.

I find the grinder super aggressive and struggle to keep I smooth surface area through out. It also seems to suck its self into the surface, like the speed of the spin is creating some sort of suction.
Also their are some thin spots around and trying to avoid eating into the fibre glass, so im just using belt sander with 60 grit and then dad comes over the top with orbital.
Getting their, just a pain around the curve of the keel

 

[PaulRainbow]

We are taking it back to the fibre glass epoxy layer and then re applying again.
But this time using a roller and having a extra helping hand to mix.
As last time my dad mixed and i applied using a paint brush
But this time we will both apply so I wont have to rush like last time

Still going with a single, super thick coat ?

I'd avoid that idea, as it's almost impossible to get enough on in one go. If you were laying up in a mould, it can be done, because you wouldn't need to sand and polish it. Applying it how you are doing it you'll need to build it up to a suitable thickness, at least 2 or 3 coats.