"Tacky" and transparent FUD after Bestine soak

[chicken45]

So, this got a 24 hour soak in the Bestine. Why does this clear area have a little tack to it? Why did the Bestine not frost it up?

[Xmtrman]

Bestine doesn't "frost it up".
Getting rid of all the wax makes it opaque.

Try a little Bestine and a brush to scrub the transparent/tacky areas and see if that fixes the problem.

I always end the process by letting all the Bestine evaporate then wash with warm (not hot) soapy water, rinse & dry.

[peteski]

I have said this a million times on the Bestine thread, but I'll say it again:    Bestine does not frost the FUD surface. It simply washes away the wax which makes the rough FUD surface appear transparent.

Example:  piece of frosted glass looks frosty (or like de-waxed FUD) becuase its surface is rough (on a microscopic level).  The glass itself is clear - only the surface looks frosted (white) because it scatters the light rays.

Now wet the frosted glass with some water - it magically becomes much more transparent and the frosted look is almost gone.   It looks like FUD with wax still on it. That is because water is transparent and it fills and smooths out the microscopic roughness of the frosted glass. When the water evaporates or is dried up, the frosted look returns.

Same goes for FUD.  When the rough surfaces (which are that way due to the printing process, most often on the surfaces which were printed over waxy supports) still have some wax resudue, the translucent wax fills the microscopic voids on the FUD's surface making it appear to be translucent. The FUD resin itself is translucent.

But when the wax is washed away and the FUD surface is dry, it will appear frosted because like frosted glas, it is scattering the light rays.

Some surfaces of FUD-printed items are printed without needing wax supports. Those have much smoother surface which will stay translucent after removing the wax (because the printed surface is much smoother to begin with).

I think that is the reason some parts of your building look smooth and translucent after the wax is washed away.  Those shouldn't really be sticky, but the smooth surface might feel sticker than the frosted areas.

That's my 5 cents worth of info.

[chicken45]

I misspoke.  I do know it doesn't "frost the FUD." I was speaking in a more general sense.
 I remember someone talking about them using UV light to help cure the resin. My concern was it wasn't fully cured on my model.

[sd45elect2000]

So, this got a 24 hour soak in the Bestine. Why does this clear area have a little tack to it? Why did the Bestine not frost it up?

I've seen this. I would try soaking it a bit more perhaps in a different orientation in the Bestine.

I assume your Bestine was fresh or filtered? The wax in suspension will deposit on the bottom of the jar and on the models.

I have about 200 Shapeways printed models of mostly interurban cars and I have had a few prints like this.

One time I evidently let the temperature of the Bestine get below 50 degree's (it was in the fall) the model I had in the Bestine soak developed a look like frost on leaves. The model was obliterated by waxy crystals. I warmed the Bestine and it turned out fine.

Randy

[peteski]

Are you sure that FUD is UV cured?  If yes, then leave it out in sunlight for a while - sun provides lots of free UV rays for all of us. 

[chicken45]

Are you sure that FUD is UV cured?  If yes, then leave it out in sunlight for a while - sun provides lots of free UV rays for all of us.

Not sure at all. I heard that from somewhere and just wanted to cover my bases.
Tonight, I'll scrub Bestine in with a toothbrush and see what happens. If not, I'll soak some more. The last time I worked with FUD, the same thing happened  in the same area of a the same print of the model.
Soaking an extra day did nothing.

I'm not sure that soaking orientation is the culprit this time. They were completely submerged, and on some other sheds, there are similar issues. I'll try to take pics of the lot later today.

[C855B]

I brought this issue up a few weeks back on receiving this FXD shell:



You'll notice the same smoothness/darkening under the cab and on the rear section of sill. I also did a double Bestine soak, and then put it under two different UV lights for about 12 hours each with no change. It was suggested at the time that this may be encapsulated uncured resin, but the UV light would have penetrated. One sample was primered shortly after, and there are no indications of issues where these darkened surfaces were.

Bottom line? Ya' got me. 

[chicken45]

Thanks for all the help, guys!

[up1950s]

Maybe we need Bettertine .

[chicken45]

Maybe we need Bettertine .

Upvotes for you, sir.

[chicken45]

All 8 sheds from the same vat:


Look closely, you can see a sticky film on there. Is that the wax that didn't dissolve? I leave fingerprints in it.




This side was completely submerged:



SO, these pieces were stuck together. It was almost like they were printed that way. I could not separate them without damaging them.

[wazzou]

Maybe we need Bettertine .

But...doesn't it go Good, Better, Best?  I think Bettertine might be less affective?   

[up1950s]

You say stuck together . That means the solvent couldn't reach the area , and the areas it did reach it only did a half assed job . I think you should bathe it in Bestine for the same amount of time as you did originally . Maybe somebody stepped on your can and it is diluted . Is this new stuff or has it been used before ?

[peteski]

You say stuck together . That means the solvent couldn't reach the area , and the areas it did reach it only did a half assed job . I think you should bathe it in Bestine for the same amount of time as you did originally . Maybe somebody stepped on your can and it is diluted . Is this new stuff or has it been used before ?

I think that it will be the best from now on to use the proper chemical name.   

What could Heptane be diluted with?  It is a solvent already.    I seem to recall that it can eventually get saturated with the dissolved wax. I also seem to recall that putting the saturated solution in refrigerator will crystalize the wax, so ti can be removed from Heptane, making it reusable.

Josh: were those buildings fully immersed in Heptane or just rinsed with it?  If the solution was contaminated with wax, wouldn't it do poor job removing wax on all the walls?