BLO cure time

Re: BLO cure time

Mark Mandell - Gone Round In New Jersey

Give it 24-36 hours to let the diluents evaporate and then go with your oil poly. The poly will incorporate the blo and they will cure "together" without incident. The additional oil may slow the poly cure a bit but the stuff takes a week to 10 days to polymerize anyway.

Re: BLO cure time

Don Stephan

Are you leaving a "wet" coat of BLO on the wood, or scrubbing the surface as dry as possible with clean paper towels after a few minutes?

Re: BLO cure time

AZ in Colorado Springs

I'm using an old t shirt. One piece to apply the BLO. Another piece to wipe away the excess after about five minutes.

Then all rags laid our to dry/cure without starting a fire.

Re: BLO cure time

John McGaw

I know this isn't useful but I'll put it out anyway: it is cured (polymerized) when it is cured -- there is no set time. The temperature and humidity have a bit to do with it but probably more important is the amount of catalyst (the modern replacement for 'boiled') the maker put in it.

When I was using BLO, before switching to straight tung oil, I usually tried to put out a drop of finish on a piece of glass or plastic and let it sit. When the drop got gummy then what is in the wood was probably good to go.

Re: BLO cure time

John in NM

If the project can stand it, give it about 20 minutes in the sun. Not sure if its the heat or UV, but it polymerizes fast in sunlight at ~6000'

For complicated builds, it might not work as well.

Re: BLO cure time

John McGaw

To expand: polymerization is a straightforward chemical reaction where oxygen, accelerated by the chemical driers (substituting for old-school boiling) cause the oil molecules to cross-link. As with most chemical reactions, raising the temperature will accelerate the rate at which this occurs. Since it is oxygen that is being incorporated I guess the ideal conditions would be heat and increased oxygen levels. That is, of course, if the project doesn't spontaneously combust...

Re: BLO cure time

JL

The answer is - it depends.

As others have said, the BLO is oxidizing. It takes as long as it takes.

I have added drying agents (either into or on top of) BLO to speed drying. It works better when added into the BLO - but you can't use the remaining BLO.

If you "shine a light" on the BLO, especially a light rich in UV rays, it will speed up the drying (sunshine works fine).

Thinning the BLO w/ mineral spirits gives you a thinner coat and seems to promote oxidation.

As always, YMMV

Thanks everyone