boat stuck in mould

this is the pva wax and gel coat i
used



if you look at this picture of the hull where the shine is, its all dented and lumped, the mold was a piece of crap i had.

the only thing now i can come up with is that im left handed and the port side of the boat is the best side, when i was waxing the boat maybe i never properly rubbed off the wax on the starboard side (right) due to been a lefty?? dunno would this matter but its what i can come up with now

 

So you used a waxed gelcoat for the boat? I can't figure out what you're saying.

 

i had to add wax solution to the gel coat so it could dry with air.

 

You need to be more clear. Which gelcoat? The gelcoat you used for repairs or the gelcoat you used for this last boat?

 

Same make gel coat but bough a new half liter tin for the repairs only.

 

He used waxed gel coat for the repairs and these spots released well.

 

Sounds like your ready to move forward, fair up the boat & create a new mold. Just thinking "out loud"(& from far away) in some of the pics esp the deeper part of the skeg/keel the gelcoat looks pretty thin- I usually allow 900 grams per meter square on the basis that you lose some when spraying to overshooting & atmosphere, also if using a cup gun/polycon( http://www.kcmouldings.co.uk/polyconspray.htm ) gun some hangs up in the cup usually about 125 grams & use this for brush touch ups to deep stuff that "shadows" when you spray--- like your keel!
Also have you hosed down the hull? reason is I don't see any evidence of PVA, usually there will be some wispy PVA film that has let go from the molding floating around--- kinda like super thin glad/sandwich wrap.
So my conclusions are that- your gelcoat was too thin in spots allowing the laminating resin to "bite" through & grip onto the mold gelcoat & that the PVA was not sufficiently thick to hold the laminating resin back from doing this. Hoping you get it sorted from Jeff.

 

What he said was I quote "the gel i layed down on the mold with the wax solution stayed and did not stick to the mold."

Which is sort of an assbackward way of saying that when he finally pryed to two apart the gelcoat he used to repair the mold was stuck to the boat. At least that's how I interpreted an earlier post.

"where ever i put the gel coat for the previous repairs on the mold, the boat is glued to it and the part where i can bearly get free on the gunnels its taken parts of the mold off and stuck to the boat, like before but alot worse"


It doesn't really matter which part it stuck to... what matters is that he didn't get a clean release and his tooling (mold) is ruined.

The reason it failed is obvious and involves not one but two missed opportunities to assure a proper release. The first occured during the waxing where each successive layer was applied in fairly rapid succession. The second and most critical failure happened when he thinned his PVA and applied an "invisible" layer.


There is a reason PVA is tinted...it's so you can see it during the application process and gauge just how much you're putting on. If you can't see a color shift then you don't have enough on your mold surface. Under some light conditions that might be hard to determine in which case you need to change your point of view and look along the surface to clearly see that wet sheen that indicates a proper coat of PVA.

Pulling parts from a mold is fraught with dangers...make even one small mistake along the way and you're almost guaranteed that you'll have a ruined part, a screwed up mold or both. Let's hope that we've all learned something from this misadventure and don't make those same mistakes again.

MM

 

I was working from my phone, now From my computer I re-read it and could get a good look at the picks I can see what the issue was.

 

i though the boat was stuck to the repairs but after cutting the mold i realised that it was not. where the repairs were done there was no fuseion between the boat and mold. i jumped the gun by saying there was.
right thats cleared, what was the issue ondarvr?
no pva left on the boat, i have a small perspex sheet and applied the pva on using a cloth, looked at it today and i could see the layer of pva dried on the perspex. i wet it and watched it come off. there was no pva on the mold.

 

What have you decided ???

Well all has been very quiet on the Irish front for a while . all repairs should have been done and smoothed over and polished etc etc . Going to make a mould off the boat ?? or retire to the country ?? i has pent hours and hours going over and over with the products you have used i cant find fault with any of them even if just either one had been used without the other . had to be something you rubbed over the mould before you gel coated it !!,like a rag with something on it that disolved the wax or ate the pva maybe , guess we will never know !.

 

weekend off, from it. flat out sanding, mini grinder, burt out, and my electric sander burn out. so its all elbow greese. but im used to that.

 

In my experience there are various sorts of PVA. I had one customer complaining about the quality of the PVA he used. Even with wax and PVA he sometimes did not get a clean pull. (luckily his products are small, and luckily I did not supply the PVA).

He now uses my PVA (Akzo brand) and has no trouble whatsoever.

I would definately spend some euros on a bottle of different PVA. Of course I cannot determine whether it is the solution, but it is cheap to try.

To Do list:
-fix up the boat. Fair her up (polyester putty and block sanding) then paint here with 2K PU paint. Leave that to cure for at least 7 days.

Lay up a panel with polyester, also putty and block sand, and the PU paint. This panel will be your experimental area. (better lose a panel than lose a boat).

Apply wax to the panel (I have never had any trouble with honey wax) and apply PVA if you wish. (you would not even need it, you can try a section without PVA). Make sure you get a nice and even film of PVA. It might bead off.

Layup some tooling gelcoat and backing laminate. Leave to cure for some week or so. Then pull and see what happens.

The system I usually recommend is:

-paint plug with 2K PU paint (regular "De IJssel" brand, which is a popular brand over here)
-apply Ferrokote FS10 sealer (3-4x)
-apply Meguiars Mirror Glaze 87 (2x)
No pva. Never had problems, except for that one time that the surface got wiped with acetone before applying the tooling gelcoat...

 

Yeah it was the reason i asked to for a picture of the products used the only thing i could see was the pva had ethanol in it . That made ne wonder !!
Ive used pva every where i been and never once had a issue with it . The guys in korea has it in flake form and just mixed a hand full with a liter of water! so i just sprayed it as he has mixed it . had no problems what so ever .
I also asked whacker82 to do a couple of tests on the old bits of his mould one with wax and one with just neat pva and just gelcoat each one but havent had any feed back so still in the dark a little !!

 

im using the mold for these test pieces, going to do alot of experments with it, just using wax, just using pva, spraying pva on, applying it on using a cloth. no water mixed. plenty to be done. just my mine is occupied with sanding. there has been alot of it. trust me