VC Tar or Epoxy following Osmosis

[Jcorstorphine]

This is a follow on from a previous post regarding treating a Westerly Pentland for Osmosis. I owned one of these boats some years ago and it had been shot blasted and sprayed with an International epoxy in 1985. A year later, the pox was back so the hull was peeled and very roughly sanded and given a number of coats of VC Tar.

I bought the boat 6 years after the VC Tar treatment and the hull was still perfectly dry, so much so that the surveyor went off to check his moisture meter but eventually declared the hull to be perfectly dry. A further 6 years on, the hull was surveyed again by the new owner and it was still dry.

My question relates to the advisability of using VC tar today as I believe that the new formulation no longer contains any tar. Will the new material be as good as the old stuff.

Thanks.

 

[JasonClark]

Hi.

My Missus works for one of the largest paint manufacturers in the country, i asked her to find out what effects the new VOC regulations have on the paint its self, so off she went to work and asked one of the scientists that come up with the ingredients for the paint, he said it makes no difference at all to the consumer as there are already new developments in place to compensate, so the consumer is basically getting the same product.

hope this helps .

 

[nimbusgb]

Dunno but I VCTarred my bottom with the epoxy version about 4 years ago. Its as good as the day I completed the job. You might as well coat the hull with industrial black plastic sheeting. Its brilliant stuff!

 

[Billjratt]

Chalk me up as another VC fan.
Does anyone agree that you should apply the first coat of antifoul before the VC is totally hard?
We did and everything went well. Some boats, however, ended up with a beautiful shiney black finish that nothing would stick to...(sanding seemed to be a retrograde step)

 

[ridgy]

Primer?

 

[oldsaltoz]

Chalk me up as another VC fan.
Does anyone agree that you should apply the first coat of antifoul before the VC is totally hard?
We did and everything went well. Some boats, however, ended up with a beautiful shiney black finish that nothing would stick to...(sanding seemed to be a retrograde step)

Works well for tar or the epoxy primers, also has the advantage of indicating when you are getting to the last layer when sanding.

 

[Bobobolinsky]

Coal Tar epoxy is certainly a good choice but sometimes needs a tiecoat for adhesion and prevent bleed through. There's a product called Protogol. Applied with a plasterers trowel it was superb at protecting steel. Now it is applied by hot airless spray as a two pack polyurethane tar. A bit too expensive to apply to a boat though. Also similar to Durathane.

 

[Pasarell]

VC Tar

VC Tar is an epoxy. Used to contain "real" tar as in coal tar epoxy but that was banned years ago as carcinogenic. Now coat tar epoxies contain a synthetic tar. Not quite as user friendly as they used to be but not a lot of difference in performance.
Coat tar epoxies used to bleed through to the topcoat but synthetic tars shouldn't do so no barrier coat needed.
Get the timing right when overcoating with an antifouling and you will have an excellent bond. Leave it a little too long though and the epoxy will go like glass and needs rubbing down to provide a mechanical key. At this time of year in the UK you should also rub down with scotchbrite pad and water / detergent to get rid of any amine bloom before sanding.

 

[nimbusgb]

Chalk me up as another VC fan.
Does anyone agree that you should apply the first coat of antifoul before the VC is totally hard?
We did and everything went well. Some boats, however, ended up with a beautiful shiney black finish that nothing would stick to...(sanding seemed to be a retrograde step)

I let mine go off completely ( about 6 months over a med summer in fact ) The finish was stunning! Shiny as anything. The first antifoul I used was a medium priced Jotun and was applied with rollers straight onto the VCtar. The boat spent about 19 months in the water in the med and although there was quite a bit of weed growth it came off effortlessly. Underneath it the antifoul still adhered to the epoxy.

Last trip out I removed and glassed in 3 skin fittings. Once done I refinished the area with VC tar again. It blended right in with no adhesion problems following just roughening up the area with 220 grit.