Varnishing process 11/7/20
Stripping
Protect all adjacent gelcoat / painted surfaces by applying regular 1” blue tape right up to the edges of the varnish. You should also double it up if its paint and not gelcoat. Paint is more sensitive to heat than gelcoat is.
I would buy a case of 1” 3M blue tape from ‘the paintstore .com’ at the same time as you order your Jen Manufacturing foam brushes. Buy at least 2 boxes of 2” brushes (will be your main brush size) and 1 box of 1” – for the tricky little areas.
With your Milwaukee heat gun set to high and your 1” Craftsman scraper – offer up the heat nozzle to the varnish – start about 4” away and gradually bring it in. The finish should start to bubble.
As soon as it starts to bubble – take the heat away and start to scrape that small area. If it doesn’t scrape readily apply a bit more heat but remember it is now easier to scorch the wood if bare wood has now been exposed by your scraping process.
With that in mind, remember to concentrate the heat ‘play’ on the areas yet to be scraped and be careful at the ever-moving ‘join’ between the varnish edge and bare wood edge – the one and the same edge.
You can ascertain how much heat you’re applying near any paint by keeping an eye on the blue tape. It will discolor slightly as you play the heat but don’t allow any of it to get really brown – that’s when you’re starting to overdo it and damage the paint beneath,
Take your time and never get the gun too close to either the wood or the adjacent surfaces – as you get the hang of it, it will become second nature.
I think the small bubbling that you will see will be your guide to enough heat being applied and also how much of an area you can scrape before applying more heat. Remember you will or should only be scraping a small area at a time – no more than a couple of square inches.
Taping up the stripped area prior to any sanding or varnishing
Once you have the section you want stripped, remove all the blue tape – your applied heat may have caused some of the tape adhesive to stay with the painted surfaces – remove with professional strength ‘Goo Gone’ – available from any good hardware store. It won’t damage the paint.
Now you need to re-tape before you start sanding and varnishing.
I use a ¼” blue plastic tape as my first tape adjacent to the wood/painted edges – it’s 3M and I get it from an automotive paint supply store – you may be able to get it from ‘paintstore.com’ – I’ve never looked for it there. (You also need to source the 60 grit – 3M purple papers described later on)
I use the ¼” tape for 2 reasons – first it’s easy to apply in a straight line and also on curves and it’s easier to remove once your 11 coats have been applied over it.
Like I said it is imperative that you leave a ‘gap’ of around 1/16” or more between the wood/paint joint. This allows the varnish to flow onto the painted surface and make a seal. You could leave a 1/8” gap if you like – you’ll never see the difference once the tape is pulled.
Now using a 1” regular blue tape go over the ¼” by about ½ of its width and then overlap a second 1” tape over the first one. Varnishing will produce some drips and a 2” depth of tape will catch 99% of them unless you’re a very sloppy varnisher.
Now you’re ready to sand.
Golden rule – ‘only ever sand with the grain of the wood’ and don’t sand towards a ‘tape’ line as the paper might get under and lift the tape. Sand away from the tape as if you’re stroking a dog.
I use a 60 grit after stripping – it’s aggressive so be careful – I cut all my papers into ‘quarter’ sheets – so with a quarter sheet 60 I will fold it in half and just sand with my bare hand – I don’t use a ‘block.’ (This is good for all your grit size sanding)
The next trick you need to know about is that applying denatured alcohol will ‘mimic’ how your bare wood will look once varnished. Buy it in gallons from a hardware store and decant into the small size carefully cleaned out ‘Dawn’ dish soap bottles.
Stripping wood will sometimes leave a thin varnish residue which you can’t readily see. Alcohol will show any of these areas up and then you need to sand a bit more – re-apply more alcohol and keep doing it until you have a regular color to all the rail.
Also to apply the alcohol and to clean between varnish coats we only use Bounty paper towel – it has a low ‘loose lint’ profile.
If you have some severe sun ’lightening,’ some fairly aggressive sanding may have to be done with your 60 paper.
Once you’re happy with a consistent color – you need to go over the area with a 220 sand.
We use purple colored ‘3M Pro Grade’ tacky backed sandpapers – buy in 25? sheet packs from Sherwin Williams or Home Depot – you’ll need 220 as your main paper, some 320 and 400 for the final sand before clear-coat. Think you can only get the 400 in 3 sheet packs. These papers are expensive but take less effort and don’t clog easily so last longer.
To make sanding easier you could use a ¼ sheet electric sander – but only on the flat upper part of the rail and use 320 grit, using 220 in a machine is too aggressive.
Sweep the bare wood with a hand brush.
You’re now ready to varnish
We only buy pints of Epifanes High Gloss Marine Varnish – shop around for the best price – buy in cases – each case has 6 pints – also has a long shelf life so don’t worry about it going ‘off.’
I decant varnish into 9oz. Solo clear plastic cups – pour back any that’s left and throw away.
Don’t thin the varnish unless you’re now using a pre-opened can – sometimes it goes slightly thick if left for a while. We only thin using ‘Interlux 333’ spirit – it’s cheaper than the Epifanes equivalent and just as good.
Apply the first varnish coat full strength – using a 2” brush for your main areas and a 1” for probably the undersides. You don’t need to thin – this first coat will disappear into the wood.
Dip each new brush into the varnish about half way and leave in the cup for about 10 seconds. This allows the varnish to soak into the foam and will now be ‘wet’ for the session.
Working from one end, varnish the whole rail as you go and try to always get the finish consistent, It’s not vital but helps.
This is true for all coating work – brush the finish on working either from left to right or right to left. Now before you load the brush again, brush the other way into the varnish you’ve just laid, lifting the brush off as you reach the point where you’d just started to lay – this will smooth out the varnish. Repeat this every time you lay a section – normally a loaded 2” brush will lay about 6” depending on width of rail.
We put on one coat per day.
For your second coat, don’t bother to sand, just go straight over the first coat.
Now you need to start sanding between every coat. Brush off the dust, no need to clean after you brush – you’re only building up a layer and sanding after each coat will smooth out any little bits of dust.
An occupational hazard when varnishing is that your brush will tend to lay a thinner coat on curves and edges – by virtue of the brushing action.
Conversely it’s easy to over-sand these areas because they present themselves too readily to your sand-papered hand.
So bear that in mind – what you’re trying to achieve is a consistently ‘thick’ varnish layer when all coats are applied. Don’t overthink it though.
So sand between each coat with 220 but don’t be over-aggressive. The sole purpose of your sanding is to achieve the best possible ‘key’ for the next coat.
10 coats later, you’ll be finished the varnish layer.
Sand with 320 and then re-sand with 400 to prepare for the clear-coat layer.
Now you need to wash the boat and dry it off – to get rid of any dust left lying around from all your varnish sanding.
Clear Coating
Awlbrite J3005 is the base clear-coat – comes in a quart.
Awlbrite J3006 is the ‘kicker’ – comes in a pint.
Awlbrite A3001 is a thinner/catalyst – comes in a pint (Some people may tell you this is not required – not so – it’s vital to the process)
So into a cup and using a ‘fine’ paper/mesh strainer (Sherwin Williams or PaintStore) put no more than 12 spoons (I just use plastic teaspoons for this) of the ‘base’ in, then 6 spoons of the ‘kicker,’ then 3 spoons of the ‘thinner.’ Mix well with the spoon – you will see it becoming clear as you mix.
Never put a ‘used’ spoon back into the ‘base’ can – the contamination will ruin the can of base.
The mix is always 4 base to 2 kicker to 1 thinner – so you can use any amount using that mix – but don’t do over 12 base – it will start to ‘kick’ before you can use it all.
Apply using the same technique but be careful – it’s much thinner than your varnish and will ‘run’ more easily. Application has to be ‘smoothed’ as best you can – but you can’t lollygag either as you need to keep the ‘flow’ going.
This clear-coat for some reason also tends to attract ‘dust’ so you need to pick the day carefully – a day with minimal wind.
Leave the clear-coat for a couple of days – it dries in a couple of hours but gets to full hardness only after 2 days.
Now you need to pull the tape.
Because you’ve now got 11 coats over the tape – this needs to be done slowly and carefully – you can easily ‘rip’ the finish off as you tape remove. Always pull tape as close to 180 degrees as you can – never pull it at right angles.
Sometimes you’ll need to scribe the ‘gap’ line carefully with a box cutter before you start to remove. Some folks recommend re-taping every 4 coats or so to make removal easier – it can be done that way but it’s a lot of work. If you’re careful we remove 11 layered tape all the time.
Remember that the clear- coat components are deemed to be carcogenic – so don’t breathe too close to the cup and always have good ventilation – not wind just ventilation.
You now know as much as I do, practice will make perfect.
Good Luck,
Mick Anderson
Naples Yacht Finishing