micro PU question

[David Schwab]

Watco is sooo slow in PDX! I once had a winter project that never dried! What recoat schedule can you use with Watco?

Really? I just follow what it says on the can. It gets very humid here, which makes things dry slower. Right now it's 90°F and 50% humidity.

This bass was finished with Watco.



Under lacquer, I just wiped on some, and then let it dry, and then sprayed right over it. Makes the wood look great:

[rjb]

It gets very humid here, which makes things dry slower. Right now it's 90°F and 50% humidity.

You call that humid? In Baltimore, the Temp & RH generally stay in the mid-90s all Summer.

-rb

[David Schwab]

You call that humid? In Baltimore, the Temp & RH generally stay in the mid-90s all Summer.

Well you are also on the East coast. I was comparing it to Arizona.

[rjb]

Well you are also on the East coast. I was comparing it to Arizona.

For some reason, I thought tedmich was in Portland.
Portland isn't exactly known as the Sunshine City.

-rb

[David King]

Watco changed the formula a few decades ago to slow down a spate of spontaneous combustion fires from folks who couldn't or wouldn't read the instructions. Once the first few coats of any oil finish go on the oil stops drying from the inside because the outer layers seal in the volatiles. The stuff stays soft forever and won't polymerize correctly. I don't think it has much to do with Relative Humidity (RH). Recently I started experimenting with the German OSMO product that's intended for floors and it's unique in that you remove it completely from the wood's surface. It seems to dry very hard. Because it doesn't build up on the surface it's strictly low luster but I'm quite convinced at the level of moisture protection and the over all toughness of the surface when dry.

[tedmich]

thanks David! I'll look up german stuff, did you have to buy 55 gal drum?

There are many potential DIY products used in the Museum/Conservator community which are ripe for use by woodworkers/ luthiers. Their requirements always include complete removal with simple chemicals, which makes sense if you're sealing up a centuries old piece of sculpture or painting. This is where Renaissance Wax was developed after all, by the British Museum. While Renaissance Wax is just micro crystalline wax Cosmolloid 80 H mixed with paraffin wax and naptha (4:1:6 wt ratio) you can substitute a resin for the wax, like MS2A or (better) laropal A81. If you use high flash naptha or pet. ether, drying times are far lower, but a little more dangerous.

I'm going to make up some of this
Cosmolloid 80 H 23%
Laropal A81 7%
Tinuvin 292 1%
VM&P naphtha 69%
(wt %)

cosmolloid/Laropal ratio governs gloss, while Tinuvin makes it VERY UV stable, could keep some woods like purple heart and Paduk from turning black with time.
oh and its ~1/3 the price too.
conservator stuff available online at
Kremer
http://www.kremerpigments.com/
Talas
Talas || Professional Archival, Bookbinding, Conservation and Restoration Supplies
CSS
Conservation Support Systems - Art Conservation, restoration and archival supplies

[David King]

Ted, you can buy the OSMO polyx oil from Environmental building supply (now Eco-house (Eko-haus?). I've also seen it at Goby Walnut and Woodcrafters in the last month. I get a .125l can for $12 which seems expensive for such a tiny quantity but it's enough for many instruments.

[tedmich]

Thanks David! Stuff sounds nice! Since it contains sunflower, soybean, and thissle oil, Carnauba and candelilla wax, you could probably drink it! (maybe not as it also has 10-25% Naphtha and ~1% 2-butanonoxime and cobalt carboxylate it probably adds nice depth and color, eh?