Re: question

George,

I have tried the sodium hypoclorite, but no better result got. I also tried
Borax, and got better results. Although there are also some bubbles. Maybe
few, but bugger than before.

The links you sent to me are great (many thanks). I have found something
relevant (at least for me). I have read that the mold must have no "black "
traces, because it indicates organic rests. The molds I tried, all of them
have small rest of "black" powder.

I preheat my molds only for 10 minutes, mybe this was not enough. Besides, I
was using a torch to do it. Maybe it's not the best way to do it.

I have done 3 more molds and they are now drying. I will try to make a small
furnace to let heat my molds for more time (using charcoal). Maybe it's
better to buy a resistance.....will go tomorrow to the shop.

Of the 3 molds, one have an especial vent hole in the side. Will try when
dry. Will post the result.

JRL


"F. George McDuffee" <gmcduffee@xxxxxxxxxxxx> escribió en el mensaje
news:9ic1h1hbkespvt88ku310g0p7hjv8ll9j4@xxxxxxxxxx
>I would not worry about "pure" sodium hypochlorite or grinding up
> the tablets.
>
> Test with a very small piece of the tablet in the molten metal to
> make sure you don't have something strange that may explode. If
> this works ok, use a half tablet to start. Use tongs to get it
> to the bottom of the metal so the chlorine will bubble through
> the metal and combine with the hydrogen. This will boil out as
> white smoke. The chlorine and other noxious gasses are colorless
> and as these are poisonous, you must not inhale.
>
> There are better degas and flux materials available than the
> swimming pool additives, but these are harder to get and more
> expensive. Unless you are a commercial foundry, the extra price
> for the specific degas/flux compounds will not be offset by the
> lower metal loss and lower [minor] sodium contamination of the
> melt caused by using sodium hypochlorite.
>
> If your feed metal is dirty or heavily corroded, you can try
> adding regular salt to the charge before you melt it. This will
> add sodium to the melt, which is not generally a concern for a
> home foundry, and will selectively deplete certain alloying
> elements such as zinc. It will however separate the dirt/oxide,
> and float it to the to where you can skim it off. It is
> generally helpful to keep a layer of flux/slag on top of the
> molten metal until just before you pour to protect it from the
> oxygen and hydrogen in the air. As mentioned before a layer of
> crushed charcoal on top of the metal will also help. I have
> never tried it but some people use crushed glass as a flux which
> melts and forms a protective film. I know of no reason you can't
> use crushed charcoal and salt at the same time.
>
> The slag/flux you skim will be a noxious material and should be
> disposed of properly, such that animals and small children can't
> get to it as it can cause chemical burns and eye/skin irritation.
>
> see
> http://members.chello.se/vikingbronze/casting.htm
> http://budgetcastingsupply.com/Metals.htm
> http://ww2.cowtown.net/mikefirth/metalctr.htm
>
> for more information and info about proper pouring temperatures.
>
> Good luck and let us know how everything turns out.
>
>
>
>
> On Fri, 26 Aug 2005 22:17:54 GMT, "jr"
> <lehmann[quitthat]@telefonica.net> wrote:
>
>>Ok. I have the tablets available now in my home. First I must check if the
>>sodium hypochlorite I have is pure.The tablets are of 20 gr, will need to
>>cut in smallest pieces. I will try it tomorrow.
>>
>>Many test to do together....:-)
>>
>>Thanks. I will post the results after the test. Thanks also for the
>>translation, but I understand better the english..:-)
>>
>>I'm able better to read and understand than to speak/write, this is the
>>result of being reading english text all the day..:-)
>>
>>As far as I see, the server has still not forward the images I posted 1
>>hour
>>ago....:-(, surely they will took more time, even though it is only 100 Kb
>>in size (both together).
>>
>>see you all tmw.
>>
>>Thanks
>>Greetings from Spain
>>JRL
>>
>>
>>"F. George McDuffee" <gmcduffee@xxxxxxxxxxxx> escribió en el mensaje
>>news:rr3vg1p2ne4g9q9on9hcs6951e7gnpb2li@xxxxxxxxxx
>>> That your casting was flat on top and did not have a pronounced
>>> "pipe" appears to indicate a significant amount of gas [hydrogen]
>>> is dissolved in the melt.
>>>
>>> Your ISP [telofonica.net] indicates you are located in Spain. In
>>> the United States, home swimming pools are very common, and thus
>>> the chemicals needed to prevent the growth of algae and bacteria
>>> are widely sold. Assuming swimming pools and the necessary
>>> maintenance chemicals are also widely used in Spain, you should
>>> be able to buy sodium hypocholorite, as this is the active
>>> ingredient in most swimming pool powder and tablet treatments.
>>>
>>> Note that this is the dry powder and adding a water solution of
>>> sodium hypochlorite to molten metal will result in a steam
>>> explosion with the likelihood of serious personal injury.
>>>
>>> In the United States, swimming pool treatments are commonly
>>> available in both powder and tablet form. The tablets tend to be
>>> considerably higher in cost on the weight basis and offer no
>>> benefit when used to degas metal.
>>>
>>> Buy the smallest possible bag of powder pool treatment that
>>> indicates sodium hypochlorite as the major active ingredient for
>>> this test. You will need a short piece [50 m/m / 2 inches long]
>>> of one-half inch [13 mm] nominal i.d. pipe. This should be what
>>> is called black iron pipe in the US meaning it is not plated and
>>> has a black oxide finish. This is commonly used here for gas
>>> pipe.
>>>
>>> To degas your metal, put a wad of soft paper such as newspaper in
>>> one end of the piece of pipe, tamp the pipe full of the sodium
>>> hypochlorite powder and put another wad of soft paper in the
>>> other end of the pipe. When your melt is up to full pouring
>>> temperature or slightly hotter, and wearing face mask, apron,
>>> gloves and other protective clothing, thrust the pipe and powder
>>> to the bottom of the crucible using tongs or a welded handle, and
>>> gently stir. The powder will decompose, liberating chlorine gas
>>> that will combine with any hydrogen in the molten metal. Be sure
>>> not to breathe any of the smoke that comes off the melt when you
>>> do this, as it is poisonous. This will also create a quantity of
>>> slag or residue that will float to the top of the molten metal.
>>> It may be helpful to cover the molten metal with a layer of
>>> powdered charcoal to protect it while melting and after
>>> degassing. You will need to skim this off before pouring the
>>> casting. Stir the metal when you degas and skim off the slag to
>>> insure you have a good mixture of the metals as these may want to
>>> separate.
>>>
>>> If this helps but does not eliminate the bubbles in your casting,
>>> get a bigger piece of pipe and use more powder. Be advised that
>>> the chlorine will also combine with any zinc in your brass/bronze
>>> and will lose excessive amounts of metal if you over-degas.
>>>
>>> [computer translation follows/la traducción de la computadora
>>> sigue]
>>>
>>> Que su echada era llana en cima y no tenía que una "cañería"
>>> pronunciada parece indicar una cantidad significante de gas [el
>>> hidrógeno] se disuelve en la fusión.
>>>
>>> Su ISP [telofonica.net] indica usted se localiza en España. En
>>> los Estados Unidos, casa las piscinas que nada son muy comúnes, y
>>> así se venden los químicos necesitados prevenir el crecimiento de
>>> algas y bacterias ampliamente. También se usan ampliamente
>>> piscinas de la natación arrogantes y los químicos de
>>> mantenimiento necesarios en España, usted debe poder comprar
>>> hypocholorite de sodio, como esto el ingrediente activo está en
>>> la mayoría el polvo de la piscina que nada y tratamientos de la
>>> lápida.
>>>
>>> Note que éste es el polvo seco y agregando una solución de agua
>>> de hypochlorite de sodio al metal fundido producirán una
>>> explosión de vapor con la probabilidad de lesión personal seria.
>>>
>>> En los Estados Unidos, los tratamientos de la piscina que nada
>>> están normalmente disponibles en los dos el polvo y forma de la
>>> lápida. Las lápidas tienden ser considerablemente más alto en
>>> costo en la base de peso y no ofrecer beneficio cuando acostumbró
>>> a metal del degas.
>>>
>>> Compre la posible bolsa más pequeña de tratamiento de piscina de
>>> polvo que indica hypochlorite de sodio como el ingrediente activo
>>> mayor para esta prueba. Usted necesitará un pedazo corto [50 m/m
>>> / 2 inches] de media pulgada [13 mm] i.d nominal. Esto debe ser
>>> lo que se llama cañería de hierro negra en el significado
>>> americano él no se chapa y tiene un acabado del óxido negro.
>>> Esto normalmente se usa aquí para la cañería de gas.
>>>
>>> Al degas su metal, ponga un taco de papel suave como periódico en
>>> un extremo del pedazo de cañería, tamp la cañería lleno del polvo
>>> del hypochlorite de sodio y puso otro taco de papel suave en el
>>> otro extremo de la cañería. Cuando su fusión es a abatanar
>>> vertiendo temperatura o máscara de la cara ligeramente más
>>> caliente, y desgastado, delantal, guantes y otra ropa de la
>>> protección, empujó la cañería y empolva al fondo del crisol que
>>> usa tenazases o una asa soldada, y suavemente el movimiento. El
>>> polvo descompondrá y liberará gas del cloro que combinará con
>>> cualquier hidrógeno en el metal fundido. Está seguro no respirar
>>> nada del humo que se cae la fusión cuando usted hace esto, cuando
>>> es venenoso. Esto también creará una cantidad de slag o residuo
>>> que flotarán a la cima del metal fundido. Puede ser útil cubrir
>>> el metal fundido con una capa de carbón de leña empolvado
>>> protegerlo mientras fundiendo y después del degassing. Usted
>>> necesitará desnatar esto fuera de antes de verter la echada.
>>> Revuelva el metal cuando usted el degas y desnata fuera del slag
>>> para asegurarlo tiene una mezcla buena de los metales como éstos
>>> puede querer separar.
>>>
>>> Si esto ayuda pero no elimina las burbujas en su echada, consiga
>>> un pedazo más grande de cañería y usa más polvo. Se aconsejado
>>> que el cloro también combinará con cualquier cinc en su
>>> brass/bronze y perderá cantidades excesivas de metal si usted
>>> encima de-degas.
>>> ============================
>>> On Fri, 26 Aug 2005 20:53:40 GMT, "jr"
>>> <lehmann[quitthat]@telefonica.net> wrote:
>>>
>>>>Yes, could be, but I don't see how to put a new degassing tube in the
>>>>mold,
>>>>this is a very easy and simple mold. Mmmmm, As I have just said in my
>>>>last
>>>>post, I will make another test tomorrow,now it's 23:00 here...:-).
>>>>
>>>>I will try to add some vents to let the gass go out. I have read the
>>>>plaster
>>>>is not so porous, so I will try it.
>>>>
>>>>Thanks.
>>>>JRL
>>>>
>>>>
>>>>
>>>>"jk" <klessig@xxxxxxx> escribió en el mensaje
>>>>news:vfvug15sqtom67vdbc14106hunlbhe1jj8@xxxxxxxxxx
>>>>>
>>>>> Could be you are not degassing?
>>>>>
>>>>>
>>>>> "jr" <lehmann[quitthat]@telefonica.net> wrote:
>>>>>
>>>>>>Mmmm, I think it would be not the problem, because the mold is an open
>>>>>>mould, so there is a lot of metal over it. Think it's a cylinder, so
>>>>>>the
>>>>>>mold only have an entry. I will try to draw with characters:
>>>>>>
>>>>>>******** *********
>>>>>>******** *********
>>>>>>******** *********
>>>>>>******** ********* Think in the figure as a box with
>>>>>>a
>>>>>>cylinder hole in the middle.
>>>>>>***********************
>>>>>>***********************
>>>>>>
>>>>>>The * are the mold, and the [spaces] the cavity of the mold. I fill it
>>>>>>all
>>>>>>with melt bronze. The result piece I get is like that:
>>>>>>
>>>>>>
>>>>>>--------------------
>>>>>>--------------------
>>>>>>-------------------[]
>>>>>>--------------------
>>>>>>-------------------- Think in the figure as a
>>>>>>Cylinder
>>>>>>--[]-----------------
>>>>>>---[]-----[]---------
>>>>>>--[][]----[]------[]--
>>>>>>
>>>>>>
>>>>>>Being the [] holes in the bronze resulted piece. Of course the "-" are
>>>>>>solid
>>>>>>bronze. It seems there were captured some bubbles in the piece.
>>>>>>
>>>>>>I will try to make some pictures right now and post here.
>>>>>>
>>>>>>Thanks
>>>>>>JRL
>>>>>>
>>>>>>
>>>>>>"F. George McDuffee" <gmcduffee@xxxxxxxxxxxx> escribió en el mensaje
>>>>>>news:tsnug11fnni5qdctg4s2ucgo3o37pshogt@xxxxxxxxxx
>>>>>>> On Fri, 26 Aug 2005 16:01:50 GMT, "jr"
>>>>>>> <lehmann[quitthat]@telefonica.net> wrote:
>>>>>>>>Hi,
>>>>>>>>I'm just trying to make a mold with plaster + kaolin (25% + 75 %) to
>>>>>>>>hold
>>>>>>>>bronze. The mold works fine but the final piece have a lot of big
>>>>>>>>bubbles
>>>>>>>>inside the bronze , so the piece it's totaly unusable.
>>>>>>>>any idea?
>>>>>>>>Thanks
>>>>>>>>JRL
>>>>>>> ==============
>>>>>>> That the bubbles are inside the casting indicates that these may
>>>>>>> not be bubbles but rather voids left when the metal solidified
>>>>>>> and shrank. Water expands when it freezes but metal shrinks by
>>>>>>> quite a large amount in volume when it changes from liquid to
>>>>>>> solid. In casting it is common to provide a large volume of
>>>>>>> liquid metal in the mold above the casting [the riser] to feed
>>>>>>> metal into the casting as it cools and solidfies. The sprues and
>>>>>>> runners that feed the metal into the mold cavity must be large
>>>>>>> enough so these will not solidify first so that additional liquid
>>>>>>> metal [from the riser] can fill any voids in the mold cavity.
>>>>>>> Design and creation of molds to allow ouring of sound castings is
>>>>>>> an art. Lindsay books has a good selection. see
>>>>>>> http://www.lindsaybks.com/prod/sub/foundry.html
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>> jk
>>>>
>>>
>>
>


.

Relevant Pages

  • Re: question
    ... I would not worry about "pure" sodium hypochlorite or grinding up ... I have the tablets available now in my home. ... >> ingredient in most swimming pool powder and tablet treatments. ... >> insure you have a good mixture of the metals as these may want to ...
    (rec.crafts.metalworking)
  • Re: Deciphering some Chinese formulations
    ... I'm nearly certain that "grass sodium" is sodium oxalate as that salt ... Another formula calls for what Google translates as "mixed lithium ... Sodium Nitrate meal powder: 71% ...
    (rec.pyrotechnics)
  • Re: question
    ... sodium hypochlorite I have is pure.The tablets are of 20 gr, ... > ingredient in most swimming pool powder and tablet treatments. ... > insure you have a good mixture of the metals as these may want to ... > los Estados Unidos, casa las piscinas que nada son muy comúnes, y ...
    (rec.crafts.metalworking)
  • Re: question
    ... the United States, home swimming pools are very common, and thus ... ingredient in most swimming pool powder and tablet treatments. ... insure you have a good mixture of the metals as these may want to ... los Estados Unidos, casa las piscinas que nada son muy comúnes, y ...
    (rec.crafts.metalworking)
  • Re: Musing about steels for woodturners. (way too long)
    ... Back in the days when I was a regular turning club member, ... I'd love to hear anyone else's take on the newest metals and their ... melting powder onto metal will make a thick ... on your vehicle, keep an eye on it for the next few years. ...
    (rec.crafts.woodturning)