Baking Soda turning yellow?

[QuintusPeltrasius]

Hey all, I'm getting ready to do a snow effect on one of the bases for my mini. Through my research (articles, forum postings here, and Youtube vids) I've seen that people have used baking soda, microballoons, crushed glass, alum, snow flock, etc...

My 2 questions are these: Can anyone with experience using baking soda for their snow effect, tell me what exactly causes the yellowing of the bicarbonate? Some sources have said sunlight, others have said that it just absorbs stuff in the air. Second question: Can sealing it really well with a varnish keep this from happening? Or perhaps, what is the best way to keep the baking soda white over time and protect it?

Thank you all... any advice is much appreciated

 

[MAXXxxx]

there can be 2 causes:
- Impurities in the baking soda. There are differences between manufacturers. --> no real way to find a good one except by trying out different ones.
- It can take up impurities from the materials it's touching/from air. --> to avoid it you'd need to protect it from the underlying material by varnishing it first, then applying the soda AND varnishing from top too (depending the snow effect this may ruin some of the finish)

The finish problem can be fixed easily by applying some snow flock (or crushed glass, etc) on top after the varnish and using those products for small things like snow on clothes.

I know I'll stick with baking soda as it's good enough for my needs, but if you want to go 100% sure it's better to use a product designed for it. They are not that expensive and unless you do whole armies in winter they last long enough.

 

[Zab]

careful with the crushed glass, if you can smell it you are already bleeding internally. wear a mask

 

[QuintusPeltrasius]

Thanks guys...

And Zab, no crushed glass for me... If I really super duper want a sparkle, I'll experiment with the alum that I saw Airhead had mentioned several times in various threads (saw his posts in my searches).

MAXXxxx, do you know if Elmer's glue has the yellowing problem? It's the glue I was considering using.

 

[MAXXxxx]

no idea as I live in the eu and Elmer's is a US brand as far as I know.

I use PVA / White Glue which should be the same and I had no problems with it.

Also a nice reference (snow is in Chapter 5): https://drive.google.com/open?id=0By8jtRYhiOr1SEtwcXB2anhHLXM

 

[ekipage]

Elmer's shouldn't yellow on you. The only reason it might is if you put it on top of paint that hadn't dried so it might pull in some of that color. It is just PVA glue as MAXXxxx said so it dries clear.

 

[MegaMole]

careful with the crushed glass, if you can smell it you are already bleeding internally. wear a mask

Seriously? That sounds a little extreme to me. Why would bleeding internally and the smell connect? I would assume it's more of an irritant the same way resin dust is.

I've heard adding white glue to backing soda will stop it yellowing. I don't know if it's a long term solution or not.

 

[EddieVanShatner]

While I have not tried it myself, I have heard that mixing a small amount of white acrylic paint to the baking soda/glue mix will prevent yellowing.

 

[bullfrog]

Seriously? That sounds a little extreme to me. Why would bleeding internally and the smell connect? I would assume it's more of an irritant the same way resin dust is.

I've heard adding white glue to backing soda will stop it yellowing. I don't know if it's a long term solution or not.

I think Zab meant it as a joke, but on that note...... mice and rat baits are made out of ground glass and a blood thinner so they bleed to death internally. If you get a little to close to the crushed glass you could possibly do the same. Injury from ground glass is much more serious than a singular cut. Because it’s so fine it’s possible to inhale it inadvertently. Not likely unless you deliberately breathe it
in though. Again.....wear a mask.

Not all white glues are created equal. I’ve heard that the Elmer’s all purpose white glue has major issues with yellowing. Go for the Elmer’s craft glue as it is acid free. The yellowing occurs due to a chemical reaction between the glue, oxygen and to a lesser degree UVA.
You could also try Vallejo water effect instead of glue. I haven’t had yellowing at all with that. I have read elsewhere that Pledge Future floor finish instead of white glue works brilliantly if you want glistening snow. Although that tip is mainly for those in the states.