Homebrew PCBs

While I was out yesterday, I saw that there were basically 3 kinds of 
spray starch available... regular, heavy, and a non-stiffening 
sizing. I'm not yet set up to etch, or I'd try all 3 myself and 
report back. Is there any kind of "test etch" pattern set up for 
testing these things? Different trace widths or whatever?

Also, I've heard at least some transfer paper is covered 
with "dextrin", a sugar. Just thought I'd pass that on...

On Wed, 10 Mar 2004 20:49:53 -0000, pygar2 <pygar2@...> wrote:

> While I was out yesterday, I saw that there were basically 3 kinds of
> spray starch available... regular, heavy, and a non-stiffening
> sizing. I'm not yet set up to etch, or I'd try all 3 myself and
> report back. Is there any kind of "test etch" pattern set up for
> testing these things? Different trace widths or whatever?
>
> Also, I've heard at least some transfer paper is covered
> with "dextrin", a sugar. Just thought I'd pass that on...
>

I somehow doubt spray starch is really what will work, but try......


A test pattern, which everybody can use, would be great,
we could then compare results better.
However it should not be too big, or maybe we need different sizes.
I think a discussion what is the best pattern is on topic.
it should be able to show minimum line width and spacing, and
also it should show how "black" areas come out.
for me a size of 5cmx5cm would be in the interesting range.
i suggest distributing it as PDF and as high resolution image.

discussion very welcome.


ST

--- In Homebrew_PCBs@yahoogroups.com, "pygar2" <pygar2@y...> wrote:
> While I was out yesterday, I saw that there were basically 3 kinds of 
> spray starch available... regular, heavy, and a non-stiffening 
> sizing. I'm not yet set up to etch, or I'd try all 3 myself and 
> report back. Is there any kind of "test etch" pattern set up for 
> testing these things? Different trace widths or whatever?

Is spray starch for fabric really "starch" as in food starch, like
wheat paste?

> Also, I've heard at least some transfer paper is covered 
> with "dextrin", a sugar. Just thought I'd pass that on...

Interesting. Possible problem: Sugar melts. Don't know at what
temperature.

OK, Niagra Spray Starch:
http://www.niagaraspraystarch.com/index.asp

Excerpt from their FAQ:

****************
Q. What are the ingredients in Niagara Spray Starch?
A. Niagara spray starch is made of modified corn starch, for body,
silicone to help prevent the iron from sticking, fabric softeners,
borax to keep the starch from breaking down, preservatives to prevent
microbiological growth, and fragrance to give a pleasant smell.

Q. What are the ingredients in Niagara Sizing?
A. Niagara sizing is an aerosol spray made of cellulose gum, for light
body, silicone to help prevent the iron from sticking, fabric
softeners, borax to keep the starch from breaking down, preservatives
to prevent microbiological growth, and fragrance to give a pleasant smell.

Q. What's the difference between starch and sizing?
A. Both starch and sizing are ironing aids, which put a finishing
touch on your fabrics.

    * Starch is best used with natural fibers, such as linen and
cotton. Starch adds both body and crispness appropriate for natural
fibers.

    * Sizing is designed to be used with synthetics, like rayon and
polyesters. Sizing adds body without crispness. Sizing can also be
used on natural fibers when you prefer to give fabrics soft body
rather than stiffness.
****************

Sugar melting points;
Sucrose, 160 to 180C:
http://ptcl.chem.ox.ac.uk/MSDS/SU/sucrose.html

Dextrose crosses to Alpha-D-Glucose, 156-158C:
http://ptcl.chem.ox.ac.uk/MSDS/GL/alpha-d-glucose.html

Dextrin says "Starch Gum" (starches are related to sugars), no temp
listed here:
http://physchem.ox.ac.uk/MSDS/DE/dextrin.html

Hmmm, dextrin does not appear to melt. This says "Not Applicable"
under "Melting Point":
<http://209.64.21.115/msds/msds.asp?Prod_num=0281836&LangCode=EN&CtryCode=US&FileType=RTF&DocType=MSDS&File=MSDS.PDF>

Steve