anodizado

10/16/2011 0 CommentsAnodizing and dying aluminum without battery acid

Video and writeup below

The anodizing and dying of aluminum parts at home has long been a popular project for many people. But the

use of battery acid, typically (29% to 32% sulfuric acid) causes concern and reluctance, and prohibits others

from even trying to anodize aluminum at home. It can be difficult to store, dangerous to skin and clothing, and in

general, not fun to work with. OSHA lists it as corrosive. This project provides an alternative to the use of liquid

sulfuric acid and uses instead, a granular pool chemical that is easy to find, mix, store, and work with. OSHA

lists this chemical as only an irritant with no shipping restrictions. Disposal is straightforward using baking soda

to neutralize and the results are comparable to those obtained with the use of the sulfuric acid method. The

alternative chemical is sodium bisulfate (NaHSO4) the sodium salt of sulfuric acid but in weaker form. It is also

known as sodium hydrogen sulfate and is used to lower the ph in home swimming pools. As in the use of any

chemicals, care and caution are in order. The following video is a project overview followed by a step- by- step

write-up:

Author

The author has an eclectic

background in chemistry,

electronics, writing, mental

health, and community

action...Ken

Archives

October 2011

September 2011

August 2011

July 2011

June 2011

May 2011

Categories

All

Anodizing Aluminum

Bar And Cr Code

Chemical Art

Cold Cathode

Color Hot Glue Sticks

Common Chemicals

Copper Plating

Cyanotype/Blueprint

Dot Com

Electroluminescence

Epoxy Art

Experiments

Magnetic Money

Photograms

Science

Observations

Home Observations Trendcasting Odds 'n Ends Science/Technology/Experiments

Observations - Science/Technology/Experiments http://www.observationsblog.com/sciencetechnologyexperi...

1 de 11 18/10/11 01:01

Aluminum and some other metals have a naturally occurring barrier coating that comes about because of a

reaction with the oxygen in air. In the case of aluminum, that barrier is aluminum oxide, Al2O3. All processed

aluminum has this coating. But, it has long been known that by using an electrolytic process the metal can have

additional protection.

In general there are two types of barrier coatings. The first is a thin, hard coating that increases the hardness

and insulation properties. The second is a porous cellular structure that allows a dye to fill in the cells and

provides a decorative and protective coating. This is the structure that is needed for this project. After the dye

has filled the anodized cells with color, the piece is placed in boiling water for 20 to 30 minutes to seal the dye in

completely.

Required materials:

· Sodium Bisulfate, NaHSO4, also called Sodium Hydrogen Sulfate. The pool additive used is

balance+protects- pH down. I found this and similar products to lower pH in pools at both a garden center and

the hardware store. Look for the chemical name and at least 90% active ingredient.

· Sodium Hydroxide. (Optional) NaOH also called drain cleaner or lye, available at all hardware stores.

· RIT liquid dye. I have used several colors but only in the liquid concentrated form. The dry packets may

work but I have not tried them. Available in grocery, drug, and hardware stores.

· Battery or source of DC current. A 1.5 volt D cell can be used. I used a rechargeable 6 volt battery but a wall

wart will also work well. This project likes relatively low voltage and current less than 400ma for these small

parts. Slow anodizing seems to work best. Voltage and current guidelines for larger pieces will be listed in the

closing comments.

· Aluminum or Lead for the cathode. (Negative Battery lead). Both are essentially inert in this chemical. Some

aluminum will be deposited at the cathode but it can be removed easily.

· Aluminum metal to anodize.

Procedure:

Make a 2% (dilute) solution of sodium hydroxide (Drain Cleaner, NaOH) if you desire an etched surface prior to

anodizing. 4 grams of NaOH in 196 ml of tap water. Or, ¾ cup water to 1 teaspoon NaOH. Mix with plastic or

wood tongue depressor. Distilled water is best if you have some. This will be used to clean and prepare the

aluminum surface. This measurement is not critical!

Make a 20 % solution of Sodium Bisulfate, (pool Ph down), also called sodium hydrogen sulfate. 40 grams of

sodium bisulfate in 160 ml of tap water. Or, 2 and ½ Tablespoons sodium bisulfate to 2/3 cup water. Mix well with

plastic or tongue depressor. Ph will be between 1 and 2. This can be increased up to 30% if needed.

Make the RIT dye solution. General guideline is 5 ml liquid dye with color of choice to 250 ml of water. Or, ½

Tablespoon dye to 1 cup water. This measurement is not critical and the concentration can be increased based

on results.

Process:

Prepare the aluminum for anodizing by cleaning thoroughly. I typically use fine steel wool to remove the surface

contaminants and reduce imperfections. This is followed by a wash with a Scotchbrite pad and dish detergent.

Rinse well and either proceed to the sodium hydroxide etch for 2 to 3 minutes and rinse again, or go directly to

the anodizing solution. The etch step provides some “bite” for the solution and allows for slightly larger cell size.

Aluminum alloys are highly variable so experiments with scrap pieces are encouraged.

Technology

Yogurt

RSS Feed

Aqua Chem


2 de 11 18/10/11 01:01

10/09/2011 0 Comments

Attach the negative battery lead to the cathode which should be at least as large as the piece being anodized.

Attach the positive lead to the piece to be anodized. Picture at end of post.

Small bubbles of hydrogen will be seen at the cathode. The time required for anodizing depends on alloy

composition, current draw, solution temperature, and solution concentration. Start with 30 to 60 minutes. A good

indicator is that the piece will have a slightly yellow tinge as the index of refraction changes with cell growth.

Rinse the completed part in cold water and place in the dye bath at room temperature. Allow about 60 minutes

and rinse the part in cold water. If the color density is low, place it back in the dye bath for a longer period.

When the color is correct, place the piece in boiling water for 20 to 30 minutes to seal in the dye. If a further

protective coating is desired a clear coat of spray acrylic can be added to highlight the color.

For reference purpose, here is the formula that was used to anodize the control with the battery acid method. 50

ml of battery acid (30% H2SO4) , to 150 ml tap water.

Closing thoughts and link:

The current required for anodizing in general is very much a variable, but a guideline is 2.8 to 10 amps for one

square foot of aluminum. This process is very open to experiment and optimization.

Two ideas that I have not tried yet is to raise the temperature of the anodizing solution, and the thought that it

would be helpful to find a material to resist anodizing solution attack. I have tried Sharpie and Krylon clear acrylic

spray with some fair results. Any ideas and comments would be appreciated.

The link for the Encyclopedia of Electrochemistry is here:

Add Comment

Looking for some chemicals?

There are occasions when a project calls for some

chemical solvent, polymer, or a chemical that you just do

not have in your possession. But, the chemical that you

need may be as close as your local hardware store,

garden center, or drugstore. Hardware stores carry

acetone, methyl alcohol, toluene, xylene, and

trichloroethylene, as readily available solvents. If you

need methylene chloride, look at paint strippers. Need

some tetrahydrofuran ? Look for some PVC pipe cleaner.

Polymers are almost everywhere including the home.

High and low density polyethylene, polystyrene, polyvinyl chloride, and others. Polyvinyl acetate is Elmer's glue,

polyvinylidene chloride is Saran wrap, and disposable diapers contain the water absorbing polymer

polyacrylamide.

The garden center has the biggest selection of really good chemicals. Sulfur, Urea, and other soil amendments,

3


3 de 11 18/10/11 01:01

09/27/2011 0 Comments

09/14/2011 0 Comments

root killer also known as copper sulfate. The two main drawbacks with local chemicals are the purity, and

amounts available. Generally speaking the chemicals are not reagent grade. They may only have 90% active

chemical but frequently that is enough. Sometimes these impurities can be removed by recrystallizing in an

appropriate solvent. And, at times, the only available size may be 5 pounds or more.

Another possibility is that some chemicals that are hard to find can be made from common chemicals. For

example, iodine is hard to find but can be made from potassium iodide which is available. I generally start with a

search for the chemical and then find out what it is used for. A little research can go a long way. But, a good

source is to check out the Commonly Available Chemicals list compiled by science educator and consultant,

David A. Katz. It was designed for schools that have a limited budget. The PDF is here. Happy Hunting!

Add Comment

Cold Cathode Lighting...

A cold cathode fluorescent lamp (CCFL) is a type of gas-discharge

lamp similar to linear fluorescent or compact fluorescent lamps.

CCFLs are used in a number of different specialty applications, such

as cold-weather lighting, display back lighting in LCD laptops, and

signage. They are known for high efficiency, long rated life, and their

ability to start in cold conditions. The 15 inch that I tested only draws

150 ma and is rated for 50,000 hours!

How do they work? A cold cathode lamp functions by using electricity

emitted from the cathodes to excite mercury vapors using the process of inelastic scattering in order to create

fluorescence, just as a typical linear fluorescent does. What sets the cold cathode lamp apart is that by using

higher voltage, a cold cathode lamp does not require the cathode to be heated in order to fire and produce light.

This allows it to draw less current, run cooler, and last longer. They can be very bright, do not flicker, and are

totally dimmable.

These lights are available in both 120 Volt and 12 Volts and come in many colors. They arrive with the 680 volt

invertor. The 12 Volt that I used had a 4 pin Molex connector but I cut it off and just used a wall wart, 12

Volts@500ma and connected the red and black leads. These are really inexpensive and fun to experiment with

so have some fun. There are so many sites that offer these lights that I did not post a link. Just search "Cold

Cathode"Let there be light...

Add Comment

Epoxy adhesive as art?

0

0


4 de 11 18/10/11 01:01

09/01/2011 0 Comments

Epoxy is one of the primary adhesive technologies and is used extensibility in industry and in households

around the world. It is available as one- part, two- part, paste, and with variable set times. It can help build,

repair, and form castings to encase items for show. A very versatile material as an adhesive. But, like everything

I see, I want to use it in a way that it was not really intended. So, the photo above shows the capture of a

magnetic force in 3D.

I used a two- part 5 minute set epoxy (Devcon), but any quick set should work. I mixed a black pigment into the

epoxy and then added the hardener. I had some epoxy pigments for coloring epoxy from TAP plastics, but any

enamel paint, or shavings from oil pastels will work. I then added some iron filings purchased at a local toy store.

But water soluble dyes fail to work so food coloring is not usable. And, in fact, no color is necessary to show the

effect. I let the epoxy set for about three minutes to increase the viscosity and then placed the magnets near the

epoxy and the particles were attracted to the magnet. Holding for another minute and the epoxy form was set.

This photo shows a combination of two colors

blending together. I just dropped a little white mix onto

the black still unset epoxy. I then used a toothpick to

make swirls. I just had to go fast and probably should

have used a slow set epoxy. It sort of looks like

enameling. Both of these ideas are really crude and

need refinement. But I wanted to post so others can

try these ideas or discover others. As they say

"beauty is in the eye"...

Add Comment

Autocatalytic deposition of copper

Autocatalytic deposition of a metal in ionic solution is sometimes

called electroless plating. In this case we will be plating copper onto

an iron surface without any electricity. The process has been around

for a long time and has many interesting applications. In this

experiment we will use 1/4 cup of distilled white vinegar, and 1

teaspoon of regular salt and dissolve with stirring. The salt is added

to the vinegar (5% Acetic acid) to provide more of an electrical

carrier. (More conductive). Old pennies that have reacted with the air

over time form copper oxide on the surface. Copper without the

oxide is bright and shiny. If you place about 10 old dull pennies in the

vinegar, the oxide will be removed and the pennies will be bright. The copper from the copper oxide that has

been removed is now in ionic form, not as the metal. This makes it chemically available to plate out on iron.

0


5 de 11 18/10/11 01:01

08/10/2011 8 Comments

Leave the pennies in the solution for about 5 minutes then remove and rinse. Note: If you leave a couple of the

pennies wet with the solution, they will form a green "patina" in about an hour, which is an accelerated form of

copper oxide. Place an iron nail or other piece of iron in the solution for about 30 minutes. You will see the

copper actually plating out on the surface of the iron. Shiny screws, nuts, and washers fail to work as they are

bright and have been coated with zinc (galvanized) to prevent rust. So, you really need plain iron.

This experiment is a fairly simple demonstration of

electroless plating. But, the process used in industry is

much more complicated and involves a lot of "secret"

protected chemistry. It is used extensively for plastics

which are not conductive at all. They are "seeded" with

a conductive chemical and then copper plated with a

strike coat. This is just enough to make them

conductive and can then be plated with other metals such as chrome or nickle. Enjoy...

Upcoming posts: Ultrasonic cavitation, Cold cathode lighting, and a really cheap Digital counter.

Add Comment

Make your own color hot glue sticks!

Due to the high readership of this post it will remain

posted for one more week. Thanks to all for the interest

and great comments...Ken

Hot glue guns and hot melt adhesives are a part of most

homeowners, hackers, and craft folk’s arsenal.

Generally speaking, they are an effective way to bond a

variety of surfaces. But what happens when you want

some color other than clear or amber? Well, you can buy

color glue sticks with a limited range of color at a high

price, or follow this project and make virtually any color

as needed. The slideshow is intended as a guideline for

making a limited number of hot glue sticks at one time. It

is not intended as a method for mass production.

Domestic hot glue adhesives are all over the map in composition, open time, tack, viscosity, and bond strength.

Many are based on ethylene-vinyl acetate with added modifiers. The two sizes most easily acquired are 11 mm,

(7/16"), (.43”), and 7mm, (9/32"), (.28”) diameters. The standard length is 4”. For this demonstration I am using

standard “Surebonder All Purpose Glue Sticks”, 11mm, the most commonly available size. But, there is the

opportunity for experimentation with all of these hot glue adhesives. The key to this process is the Reynold's

parchment paper which is coated on both sides with silicone. It is food safe and performs up to 420 Fahrenheit.

0


6 de 11 18/10/11 01:01

It is a great release agent for hot glue.

CAUTION: Hot glues guns operate at close to 400 Fahrenheit and can cause burns. This project is not for

children, but for responsible, safety conscious adults. There is more surface area when heating in an open

container and more fumes as well. Due to the unknown composition of hot glue adhesives it would be advisable

to do this project in a well ventilated area.

Parts and pieces:

Brass tube 12 inches long, 17/32" diameter, .014 wall thickness. K&S Engineering Stock# 140 .

Available at Ace and True Value hardware as well as others. K&S home here:

Reynold's Parchment Baking Paper. Others may work but this is the one that I used.

Silicone spray (Optional but helpful to protect tube exterior and other surfaces from unwanted hot glue

adhesion.

Standard hot glue sticks for melting.

Color crayons. I used Crayola.

Disposable metal container for melting and mixing hot glue. I used a tuna can fashioned with a pouring

spout.

Tips and tricks:

If there is difficulty with pouring, make a silicone funnel as shown. You can also make a cardboard funnel with a

parchment paper insert if no silicone funnels are available. Silicone seems to be the best material for release

properties. You can also add up to 10% by weight of paraffin wax to reduce the viscosity without sacrificing bond

strength. Preheating the tube while heating the glue/color can buy you a little more pour time. Let filled tube cool

about 20 to 30 minutes and disassemble. Parchment paper can be reused many times.

Before cutting the tube, wrap a glue stick in the parchment paper and push it beyond where you will make the

cut. This will reduce the depression made by the tubing cutter.

There may be some variability in the tubing ID so making the parchment paper longer will decrease the finished

stick diameter.

As in any additive color system, white crayon can be added to lighten the color.

Good luck and let me know if I can improve the process. Thanks, Ken...


7 de 11 18/10/11 01:01

08/02/2011 0 Comments

07/21/2011 0 Comments

8 Comments

Art and Chemistry

I have always been interested in art but, unfortunately have very few skills in creating

original images with traditional media. But I have been able to use chemistry to do some

interesting and creative image making. For example, moving images with chemical

clock reactions, chromatography, and food coloring with milk and dish washing

detergent. It may sound unlikely, but the latter is a good example of kinetic art. I have

made a short video and that follows with the easy instructions. Anyone can be a kinetic

artist with simple chemistry!

Place just enough whole milk to fill the bottom of any container. Whole milk contains about 3.5% fat and either

skim, 1% or 2% will not work. Add a few drops of at least three different food colors. Then add a drop or two of

liquid dish washing detergent and watch the show.

The explanation:

Dish detergent has a material called a surfactant, or surface active agent. The molecule has two ends, a head

and a tail. One end likes water and lowers the surface tension. The other end likes fats and lipids and dissolves

fats which is why they can clean dirty dishes. In this demonstration, the surfactant is dissolving the fat and the

water portion is attracting the food color. I will post other demonstration on chromatography and chemical clocks

at another time. If you come up with an interesting idea, please pass it along in the comments. By the way, Don't

drink the milk...

Add Comment

Bar and QR Codes

Almost everyone is familiar with the Barcode, also known as the Universal Product Code (UPC). It was

6

0


8 de 11 18/10/11 01:01

07/13/2011 1 Comment

introduced in supermarkets for inventory control 1n 1974. Today, every product has at least the barcode

attached for scanning. The image on the right is a QR, or Quick Response code. Both of these codes use OCR,

or optical character recognition software to be scanned and read. But that is where the similarity ends. The

barcode has space for 20 digits and is read by interpreting the width and space between the bars. But it can only

read in a horizontal plane.The QR has a capacity of 7,089 characters and can read both in the horizontal and

vertical plane! The three squares in the QR allow the code to be read in any position so that scanning is very

fast, in milliseconds!

The QR code was developed in Japan by a subsidiary of Toyota, Denso Wave, for the inventory of automobile

parts. Introduced in 2000, the QR caught on and soon smart phones had the ability to take a photo of the code,

read it, and allow the consumer to go to a website, a magazine, download an mp3, or find a sale in a nearby

store. The concept has been slow to catch on here but with the explosion of iphones, it will not take much longer

to be a dominant code. There are code generators available on the web so try it out.

I was doing some exercises in imagination and it may be possible to get even more information in the code by

using 3D technology or by using color. Interesting thought. Just another project! Click click...

Add Comment

Cyanotype/Blueprint

As promised in the last post on photograms, here are my results with real blueprint or cyanotype chemistry.

Photo 1 was made using a high contrast negative on inkjet transparency. Photo 2 is a negative printed circuit

image that I had made some time ago. Photo 3 is the dye made from the reaction of the two chemicals used

after the mix was exposed to light and the water evaporated. The dye formed is Prussian Blue, sometimes called

Turnbulls's Blue. The chemicals needed and the formula are below, and at the end of the post, I will provide a

source of the ingredients, and a great reference site:

Potassium Ferricyanide (10 grams dissolved in 100 ml distilled water) Sensitizer called part A.

Ammonium Ferric Citrate Green Variety (25 grams dissolved in 100 ml distilled water) Sensitizer called

part B.

Mix part A with part B in equal amounts in subdued light. (About 15ml for an 8X10" sheet of paper).

Coat paper with a foam brush in subdued light. Watercolor or coated inkjet paper works best but any

paper will provide an image.

Let paper dry in a dark place. Image in the sun or source of UV for 10 to 20 minutes. Color of the image

should be almost gray or appear over-exposed.

Rinse image in a couple of changes of water and let dry. Image will intensify as it dries.

This should provide a good start as to what can be an addictive hobby. It can be a real challenge to get images

that are exceptional, but also great fun. As with all chemicals, be careful and locate the MSDS, (material safety

data sheets) on both chemicals. A very good site for cyanotype and other photographic processes can be found

0


9 de 11 18/10/11 01:01

07/06/2011 0 Comments

here. A site that I have used successfully for these chemicals and other photographic chemicals also sells a

cyanotype kit. From the description, it appears that you only have to add distilled water and mix. It is less

expensive to use the kit if you only want to try out the process. But the other chemicals are available in several

different quantities if you want to go further. I have had good service from here. Good luck and send questions in

the comments section and I will update the post.

1 Comment

Photograms without the paper...

Photograms are images made on photosensitive paper called Sunprint. The paper is essentially blueprint paper

or some form of cyanotype. The chemistry is potassium ferricyanide and iron ammonium citrate in solution.

More about this at the end of the post. The image is made by placing an opaque object on the paper and

exposing it to the sun. The image is then washed to remove the unreacted chemicals for semi-permanence. But

what can you do if you don't have the chemicals or the Sunprint paper? Make your own using construction

paper! Most dollar stores have variety packs of construction paper in many colors. This paper is cheap because

of the low quality of pulp used, and the dyes that are called fugitive. They fade easily in the sun. So, I took

samples of all of the colors in the pack and placed opaque quarters on the samples and put them is the sun for

six hours. I wanted to use reflective metal to minimize the effect of heat on the dye. See before and after photos

below:

The sample with the most contrast seemed to be the red, so I used a fern under a piece of glass to make the

image in photo one at the top of the post. But this has other potential as well. How about testing several types of

clear plastic the see if they have UV absorbers? Or different colored plastic? Theoretically, yellow or amber

should block blue and UV while blue will pass all blue and UV. What about putting a thin film of sunscreen with

different SPF values. Well, you get the idea. For the next post I will show how to make blueprint paper with the

above mentioned chemicals. Pretty cool and the image only requires about 20 minutes of sunlight. Stay really

still and smile!

0

0


10 de 11 18/10/11 01:01

<< Previous

Add Comment


11 de 11 18/10/11 01:01

anodizado

Documents

aluminum surface

aluminum metal

aluminum parts

aluminum oxide

case of aluminum

processed aluminum

solution of sodium bisulfate

sodium bisulfate nahso4