Varnish woes

[Wouldchuk]

evening all,

I've recently made some kitchen cabinets from beech-veneered MDF for my narrowboat and as always was in a rush to progress so went for the first quick-drying varnish I could find - Ronseal Quick-Dry 20min clear satin finish stuff.

I didnt really think but now realise it was the acrylic stuff and i've since been told by someone who isnt a total beginner like I am, that this stuff isnt much good to seal against water as it will just dissolve and that I should have used a polyurethane varnish.

A) is that correct? I wanted the cabinets to be well sealed in case my dodgy plumbing leaks, and to protect against the condensation/damp that is inevitable in a 1960s boat...

B) should i apply PU and if so can i just put some over the top of the existing two coats of acrylic

C) will PU varnish yellow - even if on top of the acrylic - i really dont like that yellowed colour and would want to avoid it

Or should i stop worrying and leave it? There are some pieces already installed and im not taking them out again so i could only redo those bits i had access to anyway...

This is just one of many 'learning curve' moments in my first significant woodworking project - i probably should have just made a simple stool or a box....!! At some point i will upload the pictures to the builds page - a sort of 'how not to do it'!

 

[No skills]

I belive most non gloss varnishes are microporus to some degree, so thus the surfaces you have coated wont be 100% water proof.

I'll leave the difficult questions to the rest, sorry.

 

[jimi43]

I am not a great fan of acrylic varnishes and finishes but I don't believe they are necessarily "bad" in terms of waterproof protection. Yacht varnish or high quality marine varnish is the traditional finish for boats I believe (though I am not an expert).

The good news is that acrylic varnish can be over-coated...you might get better adhesion if you key it with some sandpaper first. One thing often forgotten is there are two sides to the wood...the hidden inside often gets forgotten and no finish gets applied and the damp gets in this way and warps and stains before you know it. Make sure you are covered in the hidden areas and ends!

Cheers

Jim

 

[moz]

If you are happy with the finish, relax and enjoy it. It will not dissolve. Someone is talking pure tripe. These finishes dry by evaporation of the solvent, i.e. water, and then 'cure' over a much longer period. It is is an irreversible, chemical change. It is totally different to something like shellac for example where you can reactivate it by application of the solvent, i.e. alcohol.

John

 

[tomatwark]

If you are happy with the finish, relax and enjoy it. It will not dissolve. Someone is talking pure tripe. These finishes dry by evaporation of the solvent, i.e. water, and then 'cure' over a much longer period. It is is an irreversible, chemical change. It is totally different to something like shellac for example where you can reactivate it by application of the solvent, i.e. alcohol.

John

You should be ok, alot of the big companies use water based finishes now I use water based laquer and have not had any problems other than the more opaque colour on some timbers and I think I have seen some where that alot of car paint is now water based.

Tom

 

[Dee J]

Never got on well with varnish 'til I found the quick drying acryic stuff (especially the satin finish stuff). Yacht varnish, pu, whatever - took ages to dry, and even longer to harden. Acryic is brilliant on mdf especially - use it as a sealer/ hardner before final sanding and edges especially come up loads better. Don't use it much outside - except sealing some artwork (which was done with acrylic paint anyway) - but kitchens, bathrooms etc - brilliant - never had a problem.

Dee

 

[Woodwizard]

Don't swap half way through - PU and acrylic dry to a different finish. Acrylic gives a more modern 'natural' color, PU a bit more yellow.

You can (as has been said already) overcoat acrylic with PU. If you think about it, quick drying primer is acrylic, and it is normally to over painted with oil / solvent gloss / eggshell...

But i wouldn't bother unless you expect exposure to splashes of cooking oil / curry sauce / chili sauce - the turmeric stained oil in particular seems to pass straight through clear acrylic.

I have stopped using it on table tops for this reason.

For every other (indoor) purpose, it performs and looks good - but take care for the first month or so, it seems much more vulnerable when it is 'fresh'.

 

[Wouldchuk]

Right. B*gger i then. I cannot face yet another coat, plus its mostly installed in the boat now so having wet surfaces and a Significant Other with clothes that are more suited to the ballroom than a 40ft boat, i think i will have to just see how it goes... ive taken some reassurance from here (selective hearing....!)

 

[Wouldchuk]

Right. B*gger i then. I cannot face yet another coat, plus its mostly installed in the boat now so having wet surfaces and a Significant Other with clothes that are more suited to the ballroom than a 40ft boat, i think i will have to just see how it goes... ive taken some reassurance from here (selective hearing....!)