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The Mainline => Kit Building => Topic started by: Dave K. on March 11, 2016, 05:43:12 PM

Title: Warping
Post by: Dave K. on March 11, 2016, 05:43:12 PM
Question for y'alls...

I've adopted the routine of painting the interior of my walls with flat black paint...just in case lighting gets added down the pike. But does having both sides painted (as well as braced, of course) also help prevent warping over the long haul? T'anks.
Title: Re: Warping
Post by: deemery on March 11, 2016, 07:15:32 PM
Short answer, Yes. 


(Longer answer, warping happens because moisture gets into the wood.  The paint seals the wood, making it much harder for moisture to intrude.)


dave
Title: Re: Warping
Post by: Dave K. on March 11, 2016, 07:18:48 PM
Not only do we have the midwest's fluctuations in humidity, but the layout is located in a garage (air conditioned) on a lakeshore. I've been using heavier than normal bracing as well. Maybe overkill, but I'd rather be safe.
Title: Re: Warping
Post by: deemery on March 11, 2016, 07:28:18 PM
If you want to be really safe, seal the edges as well as the sides.


dave
Title: Re: Warping
Post by: Dave K. on March 11, 2016, 08:10:46 PM
Was just thinking about that, Dave. Thanks a bunch for the input. 👍🏻
Title: Re: Warping
Post by: bparrish on March 11, 2016, 08:53:40 PM
Here is an experiment that shows what happens to wood when only painted or sealed on one side. 

Take a kitchen sink sponge.  Let it dry out completely. Press it absolutely flat.  Then pour a small amount of water on your counter top and place the sponge it.  The wet side will swell up and bend the sponge.

Sealing both sides stabilizes the wood so as moisture or humidity moves around both sides will be affected equally.  The shape will be unchanged.

See ya
Bob
Title: Re: Warping
Post by: Dave K. on March 11, 2016, 08:59:37 PM
Great visualization, Bob. Thanks! 👍🏻
Title: Re: Warping
Post by: donatode on March 11, 2016, 09:52:59 PM
Wood is known to absorb moisture.  Woodworkers and furniture makers have known for a very long time to apply finish (wet) on both sides of the wood, even if one side is not visible.  The moisture applied to both sides of the surface counteract the swelling that would have taken place if only one side received the finish. 


In our applications, if you are going to apply an AI wash to the outside, then you should at least apply the same AI wash on the inside....or rattle can it black (or any color).
Title: Re: Warping
Post by: Mike Engler on March 12, 2016, 01:04:31 AM
Does AI seal as well as the spray paint? The AI dries or evaporates so quickly I would question its sealing potential, but then I have a very limited knowledge of chemistry. Maybe AI on both sides, then spray paint one side and acrylic or whatever on the other, or is this overkill?


I spray the black not so much for future lighting, but to prevent seeing the lack of interior detail when there are windows on two or more sides. I also add black on both sides cardstock for view blocks.


I also am from the school of "you can't over-brace" structures. That's why I try to be first in line at the Mt. Albert booth when Gerry sells his bundles of odd size strip wood "seconds" for bargain prices.
Title: Re: Warping
Post by: bparrish on March 12, 2016, 01:29:35 AM
Mike .....

Good questions. AI is a color with no sealer or finish. The alcohol serves two functions. It is a diluting agent and more importantly it is a carrier.  That means a liquid to get a pigment onto something.   Almost all wood stains are some earth colored clay in an oil base as a carrier.  Minwax, for example, uses a mineral spirit and linseed oil as a carrier. In addition the company puts in some thinned varnish that is at best a sealer.

AI with its alcohol carrier leaves nothing but the blacking pigment that I think is nothing more than lamp blacking. It has no sealing capabilities. 

If anything like dull cote is used then it is best to do both sides. It is a sealer / finish in that application. 

See ya
Bob
Title: Re: Warping
Post by: Dave K. on March 12, 2016, 07:29:32 AM
Wonderful contributions, guys...thanks so much! 👍🏻
Title: Re: Warping
Post by: Mike Engler on March 12, 2016, 10:42:59 AM
So my take on a wooden building would be:


Individual boards, or board-on-board- stain both sides of the stripwood with whatever you stain with.


Board and batten, scribed siding, or clapboard sheets or die-cut pieces- black rattle-can on inside walls
and maybe rattle-can khaki followed by acrylic paint on outside? Could try your peeling paint methods!


I have a lot of structures that are AI or AI and chalk on both sides that are well-braced that haven't warped, but for the most part they have always been in climate controlled inside locations,
Title: Re: Warping
Post by: ReadingBob on March 12, 2016, 11:00:14 AM
Interesting discussion.  We have a little humidity problem down here in Florida.  It warps everything.  Even me.   ;D   

Since I moved here and most of my structures are stored in the garage with no climate control I fall into the school of you can never brace too much.  The only time I encounter any warping issues is when I apply the A&I wash or thinned acrylic paint wash during a build.  Then I figure out where I may need to add some additional bracing to straighten things out.  Fortunately I've never had a finished structure, stored in the garage, suffer from any 'post build' warping issues.     
Title: Re: Warping
Post by: Dave K. on March 12, 2016, 11:28:24 AM
Count me as a member of Overbracers Anonymous.
Title: Re: Warping
Post by: bparrish on March 12, 2016, 01:03:50 PM
Gent ...

I'm an interior guy so I try and minimize bracing when I can.  Perhaps living in downtown Idaho gives me an unfair advantage. 

I do use bracing hen I can.

See ya
Bob
Title: Re: Warping
Post by: Erieman on March 13, 2016, 10:37:53 AM
Good Morning Everyone,

This is a great topic and effects us all, no matter where you live. Living in the Arizona desert does not exclude you from the problem. I have found that long structures are especially prone to this problem. I have scratchbuilt two long structures; Ironia Station and East End Market. I learned a valuable lesson from Ironia Station. Long, narrow structures have a greater tendency to warp even with all the bracing you can install. Painting the inside helps a little and only a little. If you followed my build on East end Market, you may remember that I build the building around an inner structure ( see pic below ) the inner structure was heavily braced. The orientation of the lumber was horizontal to prevent warp. I found that this technique worked very well. it means added time and understanding of the size of the inner body. I built the inner core, then added the braced exterior walls to it. The outer walls were painted, weathered, etc. prior to installation and there were no signs of warping prior to install or after.

With Ironia station, which is 2 1/2 wide and 21" long. only the exterior walls were braced. after assembly, i noticed that one end of the building was slightly off the wooded base. That dimension continued to grow to about 3/16 or greater. Well, I fixed it by re-glueing the structure to the plywood base and clamping both ends of the station for an extended period of time. That also worked, but i would not recommend it.

The only other experience that I have had with warping was with Chester / Ft/ Edwards Station. It occurred only on the station platform extension. Both sides were painted, but the warping was very evident. The solution will make you feel a bit on edge. I held the station between my legs with the extended platform up close to my chest. ( this is not recommended for the faint of heart). The base was away from me and the top of the station was towards my chest. I grabbed the platform extension with both hands and using the end of the platform as a lever, bent the platform extension. (it gets better). Nothing happen right away. Then I heard a snap. While I thought the problem was solved, a few days later the warp was back, but not as much. So-o-o, I bent it again, waiting for the crack. Sure enough, I heard the crack and this time the platform extension warp did not return. now I cannot speak of the Ft. Edwards Station that I built for Robert Seckler, but my Chester station has stayed flat.

That's my story about WARPING.

frank / Erieman

(https://modelersforum.com/gallery/98-200615002905.jpeg) (http://modelersforum.com/gallery/98-200615002905.jpeg)