Spraying (Epifanes) Varnish

[geoffschultz]

Spraying (Epifanes) Varnish


Has anyone had any luck spraying Epifanes varnish? I've been using an HVLP to spray both the high gloss and rubbed effect varnish and am getting an "orange peel" effect. Note that this is an HVLP system with a 4 stage turbine and I'm doing this in the dead of New England winter, so it's very dry.

I suspect that my issue is the viscosity of the varnish. I'm looking for tips from people who have been able to spray varnish and turn out a "factory finish" like Freedom did when they made my boat.

-- Geoff

[David M]

What temperature are you spraying at? My rule of thumb is that if it is too cold to varnish in a t-shirt, then its too cold to varnish.

[Christian Van H]

Geoff, are you using their thinner? I cant use Epifanes at all without thinning...also, I notice Epifanes now markets foam rollers for varnishing.

[geoffschultz]

Yes, I am thinning it with Epifanes thinner for spraying. I just suspect that I have to thin it a lot more than I have been.

Based upon some info that I just found, using a viscosity DIN cup with a 4 mm hole, it should take 20-24 seconds to drain. It appears that they're suggesting a 15-20% thinning.

Now, my HVLP suggests that using the viscosity cup provided, which is equivalent to Zahn #2 (which is a 2 mm hole????), it should take 18-24 seconds for the cup to drain to obtain a usable viscosity.

On Wikipedia, I found the following formulas for viscosity:

• Zahn Cup #2: ν = 3.5(t - 14)
• Zahn Cup #4: ν = 14.8(t - 5)

Using an average of 22 seconds for the 4 mm hole, that places the viscosity at 251.6.

Using an average of 21 seconds to achieve the recommended viscosity for the HVLP sprayer, that would place the viscosity at 24.5.

That's basically a factor of 10 apart! I don't know if viscosity is linear or logarithmic, but clearly they're a long way apart, and I don't understand the differences.

Any help in understanding this would be appreciated.

-- Geoff

[Cheechako]

When building a 31 footer years ago, I put Port Orford Cedar interior ceiling strips in the whole boat, I numbered them and then sprayed them in my barn up here in wet humid Wa state. I was using a cheap airless sprayer and it turned really nice. I used McClosky's Varnish. If you are orange peeling, isnt that an indication that you are too thick or drying too fast for the thickness?

[Cheechako]

Sorry, by too thick I mean putting it on too thick, not viscosity.

[geoffschultz]

Originally Posted by Cheechako

If you are orange peeling, isnt that an indication that you are too thick or drying too fast for the thickness?

Here's a great answer that I got at SailboatOwners.com

Orange-peel is that the surface of the newly deposited layer has flashed off its solvents and has begun to 'cure' before the deeper layers have fully 'leveled out'. An HVLP puts on a LOT of material and too thick 'shots' of paint seem to orange-peel the most.
So, thin-out your varnish to the max. (recommended) shoot on successive but thin coats while carefully watching for the 'flow-out' to reduce and minimize orange-peel. The successive coats will resolubalize the thin coats underneath ... so you have to be relatively quick and not wait for the surface to cure.

A 'trick' to extend the flow time is to 'build a plastic tent' into which you can place the item immediately after spraying, in the 'tent' you've placed a few rags soaked in the solvent/reducer, and quickly as possible close the tent. The 'tent' has the minimum volume possible. The solvent-reducer vapor emissions from the rags will slow down the evaporation of solvent from the coating, allowing better 'flow-out' time ... but once you get the proper visual flow-out then immediately remove the rags or this process can dull the surface and greatly extend the drying/cure time. The excess solvent vapor in the 'tent' slows down the 'skinning-over' of the top surface and allows better flow-out.

Thinning out the varnish is your 'key'. Get a plate of glass , hold it vertical and adjust your spraying mixture of varnish vs. reducer based on how well the varnish flows-out on the vertical glass plate when sprayed ... keep adding 'drops' of either varnish or reducer to get the best 'flow' ... not sags & runs nor a 'dry' rough surface, ... and a minimum of orange-peel. Wipe the plate off with reducer if you need 'more plate'.

-- Geoff

[Joli]

Thin it down more and spray lighter coats. I cut ~30 % first few coats then go less as I build coats. I spray and brush Epiphanes and it's all about thinning. Brushing this batch, 5 coats on and 4-5 to go. I use 320 grit film between coats.

[Christian Van H]

I agree with Joli. I've found that even their thinning instructions for brushing are a little light in the thinner department... Looks like you will be experimenting...

[donw_s11]

To second what others have opined:

If you are having trouble with orange peel texture, the basic problem is that the finish is either too thick to flow, (needs more thinner), or is drying too quickly (can't flow due to solvents flashing off).

Hope this helps,

Don W.

[peterroach]

Try adding about 5% Penetrol and 10% high quality Mineral Spirits. Both are available at hardware stores. Also, if you look at the original finish you will probably be amazed at how little material they put on the surface. They tend to get a smooth finish by shooting it first and then two - three weeks later using a flat sanding block to wet sand the surface. You then shoot it again with a thin coat - Mirror.

[peterroach]

One other note - I have not had a lot of luck with Epifanes - Helmsman (yes the el cheapo) seems to last the longest and give me the best results. The Epifanes is designed for high build and I have not seemed to master this. (West Marine premium seems to be the same stuff)

[Celestialsailor]

Originally Posted by peterroach

Try adding about 5% Penetrol and 10% high quality Mineral Spirits. Both are available at hardware stores. Also, if you look at the original finish you will probably be amazed at how little material they put on the surface. They tend to get a smooth finish by shooting it first and then two - three weeks later using a flat sanding block to wet sand the surface. You then shoot it again with a thin coat - Mirror.

I'm glad you said it first!!! We also used Penetrol as a leveling agent and it worked great. Also if not mentioned earlier, some kind of water separator on the air feed.

[Celestialsailor]

I have began to use Deft product on wood. Since it is not labled "Marine", it is 1/3 the cost and it really goes on smooth.

[geoffschultz]

I talked to the "experts" at Apollo (who makes the HVLP sprayer) and they suggested that I go to a 2 mm tip and a different air cap (which directs the air at the liquid exiting the tip). They also suggested that I thin the Epafanes until I got 45 seconds thru their viscosity cup. The parts are on order from CA, so I'll let you know once I get them and try them.

-- Geoff