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Hi all. Ok I am finishing my first top ! I am using Epifanes Varnish. it has a 24 huer drytime. So far I have sprayed 4 times 24 huer apart but the last spraying was 48 huer.

here is what I have been doing so far.

Day 1. Sprayed 2 layers of shellac . Then 50/50 ratio of white spirit/Varnish. Light sanding with 320 paper ones dry (dry paper)
Day 2. 25/75 ratio of whiteS/varnish. Sanding with 400 ones dry. (dry paper)
Day 3. 25/75. Once dry, Sanding with 800grit wet paper
Day 4. ???

I seem to be getting tiny tiny specs, over the surface like dust, not sure its dust or if its my spraying. and when looking from the side of the now shiny top I see longer scratchmarks from last wetsanding. will this go away. and how should I spray this 4th coat ? and perhaps the 5th coat. what ratio etc. I am using an iwata LPH-80 that is using very low pressure. so I am spraying at 12-16 psi. 20 cm away. (thats what it is built to be spraying with) Looks georgeous now accept for the tiny specs and sandingmarks. Did not like the feel of using wetpaper !. Gonna continue spraying tomorrow at about 5 aclock my time. (Sweden)

Lars

Hey Bro,

First of all you really want to hope the "little specks" are on the surface and not too deep in the finish. The only way to get them out is either sand or scrape. I've used that varnish and although it is a great product I don't think it is well suited for our application due to the long dry time. Too much time to pick up air borne matter.

But since you're committed( to the finish ) I would try working the specks, scraping with a fresh razor blade. then wet sand with 400, 600, 800 and see how it looks. If you can get the temperature up in your dry room you can decrease the dry time considerably. And if you scrape try to do it over a larger area so not to create a crater.

FWIW lacquer is a very forgiving finish and dries very fast and I think wet sanding is a good thing.

Hopefully someone else has more ideas.

Good Luck

Lars, I would wait longer after spraying the first coat of varnish, typically I wait 2 days each for the first 2 coats. I hope for you it has properly cured. If not, your varnish will remain soft for a long time, but eventually through the years, it will cure. No need to spray 2 coats of shellac before the varnish, one light coat is enough to block the oils in rosewoods and such, and it needs to be scuffed before the first coat of varnish. I don't know what you call white spirit, but I would use either Epifanes reducer, or naphtha or *real* turpentine as a solvent.
The specks are dust that get trapped on the surface of the finish, the light sanding gets rid of them. It is unavoidable with oil varnish, given the long cure time. To avoid those as much as you can make sure you strain your varnish before pouring it in the gun, and make sure you spray in a well ventilated area free of dust (a conundrum if there is one). Another pitfall is to spray too close to another surface (such as a wall, cabinet, door and so on) and have the air and varnish particles bounce back to your guitar in the form of dust specks. Obviously you need to leave the guitar cure in a dust-free area.
Through the years I have develloped an elaborate, yet simple schedule for oil varnish, what you want is as flat a surface as you can manage to have without sanding through the layers. The Epifanes is not too amber, but if you sand through the wood it will show as a lighter area. For the first 4 coats I just scuff lightly, with 220 with the Epifanes or other softer varnishes. When I feel I have a build, I dry sand (220 if you have a light touch, 320 or 400 otherwise), trying to achieve the flattest surface without going through the varnish. After that I spray one more coat, flat sand to 320, one more coat, flat sand to 400, one more coat, wet sand to P600 and so on. I stop wet sanding at P800 or P1000 before the last coat, which should look "perfect". You may have to go back through a grit or two a couple of times if you get runs. Count on spraying at least 8 coats, probably more, the Epifanes builds fast and is high in solids. I mix it 1:1 with their accelerator, which is nothing less than added resins, and mix that 1:1 with their reducer. I add naphtha or turps as the varnish inevitably thickens in the can. A can of Bloxygen is a must.
It has done most of its shrinking and curing after about 3 days and can then be cut back and buffed, don't go through the last coat to avoid witness lines. That can be minimized by adding a bit of acetone to the mix. It will remain a bit on the soft side for a short while.

_________________
Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Thanks alot. Well the "specs" goes away easily when lightly sanding, so I to think they are dust. I am spraying water on the floor and around the shop before spraying and doing my best to keep it dust free. " hard work"
I will go buy their axelerator tomorrow .

Lars.

Lars, just a suggestion.
I have a fine dust filter (mine is a Microclene) and run this for a while after sanding, cleaning and blowing the guitars (and surrounding area ) down with air but before tack clothing them.
It filters to 0.4 micron and really seems to really help with controlling the dust for finishing.
I am wiping varnish or brushing it on in my normal workshop, which is quite dusty, although I do clean up a bit before finishing.
If your finishing area is a smallish size it may be an idea to consider.

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Great Info colin. I have just mailed them for help on what model I should use etc.

Thanks.

Lars

Lars,

You've had good advice. The topic reminded me of refinishing my mahogany speedboat. I built a
portable "clean room" of plastic pipe and plastic all around my boat after all the prep work was
done on the decks and hull. I was using Epifanes, but brushing, not spraying. I'd go out at 5:30
in the morning, wet down the ground around the boat, do a last wipe with a tack cloth, then
brush on the finish. I wore no shirt, just shorts and a hat, so no dust would come off the shirt material.
Even then, I'd always get some small dust specs, but as you've found out, they sand off
easily. You'll also see the scratches you're seeing now get less and less noticeable as the
varnish layers shrink and harden. With the boats, we'd let them harden for a week or 10
days minimum, then use wet sanding (always put a drop or two of dish detergent in the
water to break the surface tension) up to 2000 grit, and then polish out.

_________________
Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain

I tested a bunch of varnishes and decided Epifanes would be best suited for guitars. I'm glad to see Laurent using it. Laurent's a really smart person, so it makes me think I made a good choice. I've got it on guitars that are over 2 years old with no problems. I didn't like the darker color of Rockhard. It also seemed easier to scratch or ding than Epifanes, and harder (at least for me) to spray consistant, level coats.

I've never used over 25% accelerator. The accelerator is a bunch of resins, some naphtha, and a little cobalt so I suppose a 1:1 mix isn't much. Using the Epifanes spray thinner will allow it to dry a little quicker than either naphtha, or turpentine. I guess the epifanes spray thinner has............"something" in it to accelerate drying. Spraying it....."good" is a must. Orange peel, dry spray or runs are trouble. I wait at least 36 hours between coats. A light scuffing (by hand) with 400 grit is all that's necessary if it was sprayed right. The little specs are easily sanded out with light sanding. A clean spraying area is a must. I clean my spray room very good, then turn the exhaust fan on for a while before spraying. My spray booth/room is 12' X 8'. I've got a 3600 CFM fan, with a filtered 24" X 24" air intake across the room. The room is pretty much in a vacume when my fan's on. I wear a tyvek suit when spraying, not for my health, but to eliminate any dust from my clothes. I leave the fan on for ~4 hours after spraying, and I turn the body so that the treble side is up after spraying. If my pore fill was good, and I don't mess up spraying I'll have 5 coats on the top, with 6 on the back and sides. Final thickness after buffing will be around 4 mils.

I don't use any accelerator in the last coat. A minimun of 3 days after the last coat I lightly wet sand with 1200 grit and mineral sprits to get rid of the little specs, then to the buffer. It buffs easily as long as you're careful not to overheat it.

Here's a picture before buffing


Here's the same guitar after buffing.


Laurent, I'd bet you've got pictures of some really great looking varnished guitars. Let's see 'em!!!

_________________
I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Thanks alot for the inputs. Good info !! .
I put on a thick layer yesterday, so today I am just waiting and tomorrow I will sand some and put the last coat on. Cant wait. I am not much for sitting still and the sprayroom is in my workarea so I cant do anything else than wait hmm

Lars

Woody you're too kind, I'll try to post pics when I find my spouse's camera.

Lars, oil varnish is a different kind of finish.
It's not even a finish, it's a lifestyle.

Unlike evaporative finishes, if the under coats have not cured properly, your varnish will remain forever soft, preventing the outer coats to dry properly, and vice-versa. Oil varnish cures by polymerisation: exposure to oxygen, and UV to a lesser degree. There's little, if any, chemical bond between the layers. Acetone seems to help with that a great deal, and also accelerate curing a little bit.
Woody waits 36 hours between coats, and that seems wise. I wait 48 hours between the first two coats, and then 24 hours for the subsequent ones. My shop is 40% RH and 70 to 75º F, so varnish cures fast. I'd wait longer in a colder/more humid shop. I can spray Rockhard twice, or even thrice a day, but it cures much faster than the Epifanes.

_________________
Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Thank you laurent for your great input. I guess I need to be more patient from now on .

Right now my progress is in a halt as I get scratches after wet sanding, not sure what I am doing wrong, might it be that The underlayers are a bit on the soft side still and there for easily gets scratches

Lars