Working on making little exterior directional signs with a laser engraver for outside. About a square foot or smaller for each

The usual - UV protection, clear

the special, ideal need:

. No VOCs

. Dry and ready to send or install in less than four hours.

 

We are looking at SpeedoKote with an activator for  cars. . It says it is an acrylic urethane. I have no idea what that is.   I am concerned that it may not have the elasticity needed for wood.

 

OK, so if there is a compromise to get speed with VOCs, what would the solution be?

If there is a compromise to not have any VOCs but delay to 24 hours, what would the solution be?

 

Thanks,

Robert

SpeedoKote is used on plastic car bumpers so, any wood movement shouldn't be a problem. 

thanks for this.

 

I wonder if flexibility is the same as expandability.  

Also, while I understand that the two components polymerize rather than drying, there are few VOCs in the drying process. Yet, as I read the MSDS, or whatever the new name is, the primary stuff is pretty volatile  until mixed.  

 

I see an old Woodonline post to use untinted exterior paint. No pigment at all yet with UV, fungacides, mildwcides.  Does this actually exist?

@kmealy did post here about the exterior paint. Try to search for the post. I think that might be a better solution

 

Just curious, why do you have the need for no VOC? Especially for an exterior project

1 hour ago, Bob Hodge said:

I see an old Woodonline post to use untinted exterior paint. No pigment at all yet with UV, fungacides, mildwcides.  Does this actually exist?

Yes, use a deep tint base (that is, one without any white pigment added, so it's used for the darkest colors).   Thin coats   If you want the original reference, http://www.askhlm.com/Home.aspx

 

2 hours ago, Chips N Dust said:

@kmealy did post here about the exterior paint. Try to search for the post. I think that might be a better solution

 

Just curious, why do you have the need for no VOC? Especially for an exterior project

No  VOCs because my very environmentally concerned son in law doesn't like the thought of them.  It seems to me that super fast dry = dryers = VOCs, yet I am not a chemist.

The Speedokote dries by polymerization, which does not create VOCs, yet the Part 1 product is full of them, so they have to go somewhere.  This part is out of my league.  

That exterior paint article references oil based paint, and it indeed works well.....but doesn't fit your criteria. You can use exterior acrylic paint, same considerations (the one for deep colors). I can tell you that the SW A100 exterior acrylic dries clear (base #4) as does the Olympic,  but Olympic has changed their names around again and I'm not sure which one it is (the one I used was Premium Exterior Acrylic paint, or some such). I really doubt the acrylic paints are going to hold up as well as the oil based, but so far (at least for me) they are doing well.

Edited January 21, 20179 yr by Fred W. Hargis, Jr

The best way to look at polymerization is that you mix two compounds (liguids) together and they combine to form a new compound (in this case a finish).   There are some of these reactions that allow the VOCs to escape, but some reactions tie up any VOCs and don't let them loose and are considered more environmentally "friendly".   You would have to read the full SDS on the product you are thinking about using to see what is in it to start and how much is left after the reaction.   It's not a bad way to go if you have the right stuff to work with, but the deep base has even less.

Thanks for these helpful responses.  Who knew that becoming a good woodworker would get so deep into chemistry.

 

I think we are going to try both the water based, untinted exterior paint and the automotive Speedokote.  I'm tempted to devise a serious test of water spray, sun lamp, slow baking, etc to see what happens.  

Bob, can you let us know the results of your tests? It would be interesting to see.

Yes,  we'll post the test results.

I also found General Finishes 450 Water Based Varnish, an acrylic for external finishes with UV and mildewcide.  This seems to fit the criteria for no VOCs, pretty fast dry.

Thanks all for thinking this through with me.

GF 450 gets very high marks form those who use it, and it should also do well.