Waterlox?

[Ken Fitzgerald]

I bought a quart can of Waterlox. How do you guys use it in the winter time if you have a heated shop. Reading the information at their website it indicates that drying time is based on cross ventilation not temperature. I use a gas furnace to heat my shop. Do I shut the furnace off for 24 hours to dry a coat? They plainly state that 30ºF with 10% humidity will dry quicker than 90º with 90% humidity. Our low humidity will help but what to do as it plainly states it's combustible. One of the reasons I feel I don't have a lot of trouble with tool rust is the low humidity and I set my thermostat to 58ºF when I am not using the shop so there aren't a lot of temperature swings with the tools.

Advise based on experience?

[Bennett Ostroff]

Temperature is absolutely a factor in dry time, along with humidity and cross ventilation. The example they use is 30F/10% humidity with ventilation vs 90F/90% humidity without ventilation. I personally think they overemphasize the cross ventilation thing...but Waterlox is super stinky so ventilation is a good idea.

I'm not a physics expert, but I think it's very very unlikely that the vapor would combust unless you had an impossibly high vapor concentration in your garage. But better safe than sorry. I'd heat the shop and get a cross breeze going with a fan blowing out one of the windows, ideally in the direction the wind is already blowing.

FWIW, unless specifically requested, I stopped using Waterlox due to the finicky/long dry time, ridiculous odor, high cost, and skinning over of less-than-full containers.

[Edward Dyas]

I bought a quart can of Waterlox. How do you guys use it in the winter time if you have a heated shop. Reading the information at their website it indicates that drying time is based on cross ventilation not temperature. I use a gas furnace to heat my shop. Do I shut the furnace off for 24 hours to dry a coat? They plainly state that 30ºF with 10% humidity will dry quicker than 90º with 90% humidity. Our low humidity will help but what to do as it plainly states it's combustible. One of the reasons I feel I don't have a lot of trouble with tool rust is the low humidity and I set my thermostat to 58ºF when I am not using the shop so there aren't a lot of temperature swings with the tools.

Advise based on experience?

You can use an oil based finish in cold weather but you have to allow it to dry a lot longer than the directions recommend. One of the resins in Waterlox is tung oil which in itself is a very slow drying finish. You may end up having to wait a week or two between coats. The best way to tell if the finish is dry enough to recoat is to briskly rub the finish with a clean dry cloth and see if the odor of the finish is on the rag. When there is no small the finish is ready.

As far as shutting the furnace off, yes if it's gas. Any open flame can set off the fumes of the solvents in the finish. If your shop is small the fumes can build in concentration and with enough concentration the spark in a light switch can set it off.

Because it is a slow drying finish I wouldn't try to create cross ventilation due to getting dust in the finish. Once it is dry to touch you could provide ventilation for it to finish drying.

[John TenEyck]

I personally would not worry about blowing up your shop by using Waterlox while the furnace runs. I been doing it for 30 years with both my gas fired boiler and hot water heater sitting 20 feet away.

A shop at 60F or higher will go a long way towards faster drying. Your low RH will definitely help, too. The third leg of the equation is easily handled by setting a small fan to circulate air over the work. That will improve evaporation of the solvent and also provide oxygen for curing.

John

[Tom Bender]

Edward and John are both right about air movement. You need to find a middle ground. With your low RH it should be easy. Gentle circulation in a dust free room with some clean fresh air added in.

[Carl Beckett]

This is an interesting question, what amount of waterlox fumes would be required for combustion? Has anybody done any real calculations? (I did a quick search and other than lots of references on stoichiometric calcs, nothing specific to wood finishes). I can imagine calculating an entire can worth of material into a shop air volume and still not being anywhere close to what is needed for combustion. Or not.

Any of you chemistry gurus have thoughts?

(oil soaked rags in a pile are heat buildup due to oxidation, where the heat isnt being released from the inner pile - flash point would only apply directly above the oil surface so again unless smoking cigs while finishing wouldnt apply - what level of o2/fuel mix would be required for combustion? ) I have no sense of what it would take.

[Stan Calow]

Carl, there are reference books put out by DOT for transportation of hazardous materials, and one NIOSH/CDC for chemical hazards that give you the Lower Explosive Limit for most common chemicals. Its expressed as a percentage of the air (as in a room) volume. I don't know what the solvents are in Waterlox. Maybe this info is in the Material Safety Data Sheet for Waterlox.

[David Utterback]

I have used Waterlox a couple of times so not a great deal of expertise. However, I do know about indoor air quality and believe in protection of health. The dominant odor that I sense from Waterlox is phenol. The long cure time is consistent slow emission of the solvents and carriers. The chemicals would be at higher concentrations during and soon after application but then decrease as additional air circulates through the shop.

The explosion hazard from use of finishes indoors is small but could be higher from spray applications and from highly volatile materials such as lacquers, naphtha and denatured alcohol. In any case, flame sources could transform some gases but it is unlikely that the products would be at hazardous concentrations unless used for long periods of time with little dilution air. IIRC, water based finishes also contain volatile organic compounds (VOCs).

Air circulation can be indirect, i.e. not aimed at the finished piece, and in most hobby-sized shops could be directed away from the piece. If HVAC or natural ventilation is available, it should provide sufficient air movement.

[David Utterback]

Link for the useful NIOSH pocket guide on chemical hazards - https://www.cdc.gov/niosh/npg/pgintrod.html.

[Jim Becker]

I honestly do not believe there is going to be an explosive issue using Waterlox or any other oil based product in the manner we apply it. (non spray application methods) The fumes are certainly something that we need to consider for personal health reasons, but they are not likely going to be in a concentration that's going to go up suddenly just because we're in a room heated by burning something like gas in a furnace. Doing it right next to an open flame? Yea...that's not a good idea. Turning the heat off is going to adversely affect the cure time, too. Waterlox takes about 24 hours for a coat or two wiped on ... within the stated temperature range from the manufacturer ... to properly cure.

So "my" bottom line would be to make sure there is ventilation during application for sure (and maybe even a respirator for some folks) and then let it set overnight with the heat on to do what it does. I kinda agree with Bennett that I don't like to actually use Waterlox because of the l-o-n-g cure time and higher level of fumes. I only use it when I have a client that requires it, usually to match existing work. On the rare occasion where I decide to use an oil based product, it's generally something that doesn't have high odor and dries a bit more quickly if at all possible.

[Ken Fitzgerald]

I have been using it since I started this thread. I do like the results but can't handle the LONG drying time. I will not be using it again.

[roger wiegand]

Does anyone understand why humidity would have any effect on evaporation of a different, unrelated solvent? Clearly it could affect water based finishes, as evaporation of the water is driven in part by the differential in partial pressure of water vapor in the air. In general though, there is no difference in the partial pressure of the gas phase of the hydrocarbon solvents between air with 0% water vapor and 100% saturated with water vapor. This has perpetually confused me, and the assertion that it makes a difference is contrary to the simplified theory I learned way back when in Chem 101.

Ventilation is all about decreasing the concentration of the evaporating substance in the air near the surface-- again increasing the difference in partial pressure.

Temperature should be a direct effect on diffusion for the solvent evaporation as well as for the polymerization reaction. Across a very broad range of reactions (diffusion limited ones) the rate of reaction (or evaporation) should increase by about a factor of two for each 10 deg C increase in temperature. , so for going from 30 f to 90 f, that's a ~30 degree C difference so evaporation should be 2^3 or 8 times faster.

[David Utterback]

Does anyone understand why humidity would have any effect on evaporation of a different, unrelated solvent? Clearly it could affect water based finishes, as evaporation of the water is driven in part by the differential in partial pressure of water vapor in the air. In general though, there is no difference in the partial pressure of the gas phase of the hydrocarbon solvents between air with 0% water vapor and 100% saturated with water vapor. This has perpetually confused me, and the assertion that it makes a difference is contrary to the simplified theory I learned way back when in Chem 101.

Ventilation is all about decreasing the concentration of the evaporating substance in the air near the surface-- again increasing the difference in partial pressure.

Temperature should be a direct effect on diffusion for the solvent evaporation as well as for the polymerization reaction. Across a very broad range of reactions (diffusion limited ones) the rate of reaction (or evaporation) should increase by about a factor of two for each 10 deg C increase in temperature. , so for going from 30 f to 90 f, that's a ~30 degree C difference so evaporation should be 2^3 or 8 times faster.

A mystery to me as well, Roger. Here is the explanation from Waterlox. Unclear to me how higher atmospheric moisture reduces "free oxygen" other than through dilution.

Humidity. In high humidity situations, ventilation is even more critical. High humidity will impede the drying process because there is less free oxygen in the atmosphere; therefore, the lower the humidity, the better the drying conditions.

[roger wiegand]

That sounds like even more mumbo jumbo. Surely going from 21% oxygen to 20.998% oxygen (making that number up) will have no measurable effect.

I found a paper describing the effect of water on the evaporation of ethanol, where the slowing was attributed to cooling of the ethanol droplet by absorption of water from the air. I think that will only work for solvents that are miscible with water.

Water might well have an effect on the polymerization reaction. The free radical hydroperoxides formed from the triglycerides in the oils could certainly react with water rather than the other alcohols in the fatty acids and inhibit polymerization, but that has little to do with evaporation, nor with the amount of oxygen available.

I may try calling Waterlox customer service to see if they have an actual chemist on staff who can explain this.

[David Utterback]

Roger, it appears you know details of the reactions involved. I do not. Another possible explanation (from my shower this morning) is if water is a reaction product, greater moisture in the air may shift equilibria toward the reactants. Waterlox website does state that the hardening of the finish is a 2-step process of solvent (or carrier) evaporation and chemical reactions of the substrates. The latter takes months to reach final products.