Resin coat before high build

The ugly bits of building
shiraz02
Posts: 25
Joined: Thu Jul 02, 2009 8:00 pm

Resin coat before high build

Post by shiraz02 » Wed Dec 14, 2016 2:20 pm

Ready to start spraying high build (jotun). For the underwater sections I resin coated (X2) before high build. The West brown bog says to do the same above waterline too, not looking forward to it, is it really required ?
Big job...
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Finally
Posts: 223
Joined: Sat Jul 04, 2009 9:24 am
Location: Cairns

Re: Resin coat before high build

Post by Finally » Wed Dec 14, 2016 7:43 pm

Sorry - I don't know the answer but that seems crazy....but I am intrigued to find out why.

You've spent all that time fairing expensive epoxy bog to then add another coat of epoxy - which you will no doubt have to sand to key up / fair before highbuild primer? I understamd ATL's blue bog also requires a coat of epoxy before primer.

Have you been in contact with your supplier to ask them"Why?". With Jotafair and Awlfair you can go straight to the primer stage - no intermediate epoxy coat needed.

David

mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Re: Resin coat before high build

Post by mahnamahna » Wed Dec 14, 2016 9:15 pm

Hey Sean. How awesome that we are at about the same stage considering how long its been. Life huh? I did the resin coat before highbuild on underwater up to 300mm above wl but applied highbuild over tacky resin to avoid sanding or peelply. Above waterline highbuild went straight over bog. I have sanded through highbuild a little too much so am applying one more coat all over, a light wiz over with 320 grit with air rupes orbital prior to topcoat late Jan. Pretty exited. I used jotun penguard hb and have jotun imperite 300 topcoat.

shiraz02
Posts: 25
Joined: Thu Jul 02, 2009 8:00 pm

Re: Resin coat before high build

Post by shiraz02 » Wed Dec 14, 2016 9:28 pm

I think it's supposed to harden and seal the bog, plus an extra water barrier.
The trick is spraying the HB whilst the resin is tacky, too early and it sags, too late and it doesn't stick. I can't see any way of doing it except in small sections, as you lose access once sticky resin is everywhere.
I used some of the blue bog, but it's a lot harder to sand. It ( and the jotun green bog) is very good for coving though.

Just saw you reply Paul, you're up to painting too ? I'm using the Ameron polysiloxane topcoat that George and Cory used, it's pretty hard apparently. Looks like we might be hitting the water @ the same time..

mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Re: Resin coat before high build

Post by mahnamahna » Thu Dec 15, 2016 8:06 am

I had aimed in January this year to be launching now. That like all my timelines has blown out and I plan now to paint in late Jan. I reckon at least 2 more months to fit windows and bolt everything on and get systems like motors and rudders and basic electrics all working so launch say April? I am still seriously out of money so launch could also be delayed by saving for launch costs. I dont have mast posts let alone masts so I will be a 5 knot powerboat for quite a while. I will haul back out to fit all that sometime down the track. Quick question Sean. Did you use the semi rigid hydraulic lines for your uflex steering or have more flexible reinforced rubber hoses made? Did you fit it all yourself! If so do the brass connectors work well and crimp securely to the plastic hose?

shiraz02
Posts: 25
Joined: Thu Jul 02, 2009 8:00 pm

Re: Resin coat before high build

Post by shiraz02 » Thu Dec 15, 2016 9:14 am

Paul, Uflex say to use copper. I've got their tails which come with fittings to attach to the copper tube.
Hope to launch mid year too, but not definite ...

Finally
Posts: 223
Joined: Sat Jul 04, 2009 9:24 am
Location: Cairns

Re: Resin coat before high build

Post by Finally » Thu Dec 15, 2016 11:46 am

I managed to get a bit of information regarding the need for a resin coat.

In effect, if you spray thinned highbuild onto the bog you have used, the solvents in the paint / thinners will be absorbed and "eat" into the bog. May not look like it initially but over time the bog will break down and your paint will flake. The resin coat provides a barrier to the solvents. Also, I was told not to paint onto wet resin as the solvents will still flow through the curing epoxy and get absorbed by the bog - obviously not to the same extent as spraying directly onto unprotected bog.

However, having said that, I would still check with your supplier to confirm whether or not this information is correct.

shiraz02
Posts: 25
Joined: Thu Jul 02, 2009 8:00 pm

Re: Resin coat before high build

Post by shiraz02 » Thu Dec 15, 2016 12:56 pm

Thanks for that. I don't thin the highbuild, just spray it on straight. I'm sure if I asked ATL they'd tell me to resin coat, was just seeing if others have done so. 44C if you're @, what did you do ?

Finally
Posts: 223
Joined: Sat Jul 04, 2009 9:24 am
Location: Cairns

Re: Resin coat before high build

Post by Finally » Thu Dec 15, 2016 2:00 pm

There are still solvents in unthinned highbuild. After speaking to a painter, he suggests you could avoid putting on the epoxy coat by applying a thin coat of unthinned highbuild to "seal" the bog. Just a very thin sealing coat to minimise the amount of solvent ingress. The following day (within your recoat window of 24 hours) apply more highbuild as per normal. The first coat of highbuild should largely act as a barrier to the solvents in the second day's application.

If you are getting nowhere with information from your bog supplier - have a talk to your Jotun rep, he may have an alternative solution.

mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Re: Resin coat before high build

Post by mahnamahna » Thu Dec 15, 2016 8:30 pm

I have seen 2 cats leave my shed both by pro fairers and painters and neither had resin applied before highbuild it went on straight over bog. Bear in mind both also got about 5 coats of highbuild with a fairing sand in between. If they sanded through the hb they sprayed another coat. Then I think they used a primer before top coat.
In my case the hulls got a coat of microsurfacer over the bog then a coat of penguard hb. Because I sanded through that and the microsurfacer back to bog in places (about 5%) I am spraying one more hb before topcoat.

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