# discoloration when casting in resin



## GaWoodworker (Dec 26, 2005)

If I use dyed snakeskins, I have a problem that the skins darken as the resin bonds. Is there something that can seal the skins prior to adding them to resin? Any help would be appreciated.


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## PenWorks (Dec 26, 2005)

Don't think so. The resin is causing a reaction with whatever they tanned or dyed the skin with. This has happened to me when I cast the python & cobra skins from Implora. So I just cast good old regular tanned rattle snake.


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## JimGo (Dec 26, 2005)

Anthony, did you try coating with CA or something like shellac before casting?


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## its_virgil (Dec 27, 2005)

I have tried both and if the skin want to go black it will. I too, have chosen to stay with rattlesnake skins that I get from http://www.sdsnake.com  I had some python, lizard and alligator from a local cowboy boot maker and whatever they cure or dye the skins with to make them into leather does not like being eternally encapsulated in PR and turns black on us just to laugh in our face. 
Do a good turn daily!
Don



> _Originally posted by JimGo_
> <br />Anthony, did you try coating with CA or something like shellac before casting?


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## ldimick (Dec 27, 2005)

Maybe the answer is to find a different medium than resin?


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## GaWoodworker (Dec 27, 2005)

> _Originally posted by ldimick_
> <br />Maybe the answer is to find a different medium than resin?



Do you know of another medium that will produce the same clear blank as resin?


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## ldimick (Dec 28, 2005)

Yes. I know CA has been used but I don't know if it discolors the skins.


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## its_virgil (Dec 28, 2005)

PR and rattlesnake skin....how can it get any better?
Do a good turn daily!
Don




<br />





> _Originally posted by ldimick_
> <br />Maybe the answer is to find a different medium than resin?


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## PenWorks (Dec 28, 2005)

Did you use your pressure pot ?? Looks like it, that cast is crystal clear [] How about the recepie, did you go to 10 drops ? Looks great.


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## its_virgil (Dec 28, 2005)

Thanks Anthony. I will never do 10 drops again. Everything melted but the tubes.  I used 6 drops (droping back to 5 next time) and yes, this was cast in the pressure pot at 60 psi. It really is clear; I was very happy with the results . I took it to bubbasville last nite and no one could find any bubbles. It worked great. This was my first time to pressure cast. The blanks were for a baron and cigar. I gave the barron tubes to Ron McIntire and I ruined one of the cigar blanks due to my stupidity, which seems to be running rampant lately. Got the pressure pot (for paint) from HF for $79...it is a 2 1/2 gallon pot and I made a shelf for it and have two layers of shelfs to put the molds on. I can get 8 molds(maybe more) in at once, except I only have 3 at the present. More experimenting today. Chow!
Do a good turn daily!
Don


> _Originally posted by PenWorks_
> <br />Did you use your pressure pot ?? Looks like it, that cast is crystal clear [] How about the recepie, did you go to 10 drops ? Looks great.


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## PenWorks (Dec 28, 2005)

To be clear, "crystal clear"...... I ment 10 drops per 4 oz. Did you mean 5 drops per oz?  Carefull on that experimenting Dr. Frankinstein [] I would think the pressure pot would take the tempeture and the humidity out of the equation , yes ?


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## its_virgil (Dec 28, 2005)

Sorry, tht would be 5 drops per ounce. You had told me 4 per ounce, but 10 in 4 oz is even less. I'm going to make another cast today and will drop back to 4 per ounce. Don't know if the pressure pot would take the temp and humidity out or not. One would think so, since altitude (reduced pressure) lowers the boiling point just as pressure increases it...thats why we cook in pressure cookers....more pressure means more heat since the boiling point is raised. Back to the
 "La Bore Ah Torey"
Do a good turn daily!
Don


> _Originally posted by PenWorks_
> <br />To be clear, "crystal clear"...... I ment 10 drops per 4 oz. Did you mean 5 drops per oz?  Carefull on that experimenting Dr. Frankinstein [] I would think the pressure pot would take the tempeture and the humidity out of the equation , yes ?


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## GaWoodworker (Dec 28, 2005)

> _Originally posted by its_virgil_
> <br /> Got the pressure pot (for paint) from HF for $79...it is a 2 1/2 gallon pot and I made a shelf for it and have two layers of shelfs to put the molds on.


[/quote]

What company does 'HF' stand for?


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## DWK5150 (Dec 28, 2005)

Harbour Freight


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## GaWoodworker (Dec 28, 2005)

> _Originally posted by DWK5150_
> <br />Harbour Freight



Thanks, Don.


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## JimGo (Dec 28, 2005)

Thanks for the hint WRT the pressure pot.  That's a cool toy![]


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## its_virgil (Dec 28, 2005)

Jim,
Here is a picture of the pot itself. Just in cast some don't know what a paint pot really is. 




<br />
Do a good turn daily!
Don





> _Originally posted by JimGo_
> <br />Thanks for the hint WRT the pressure pot.  That's a cool toy![]


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## thetalbott4 (Dec 28, 2005)

Don-

Your casting looks great. Perfectly clear! Are you bringing the pot to 60 psi and then sealing it off with a valve, or leaving it hooked to the compressor? Pressure for entire cure time? As you lower your drops per ounce of catalyst, are you experiencing "sticky" or "tacky" castings? The first set I did are sticky on the exterior but seem to turn ok. Again, nice job!


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## its_virgil (Dec 28, 2005)

I pressure it to 60 psi and remove the air hose so I can still use the air for other stuff. The resin cures or sets in an hour our so. I just leave the pot pressurized the entire time. Mind you, this is my first casting under prressure but will not be the last. Every PR casting I have done has always been stickey on the surface exposed to the air...just that one side. The surfaces touching the mold are totally non-stickey.  Don't know why...that's the way it has been.Thanks for looking and comments. I normally use 7 drops per ounce but am reducing that. I am now to 5 per ounce and my next cast will be 4 per ounce. Anthony Turchetta in a post earlier in this thread mentioned 10 drops in 4 ounces. I am working towards that and comparing the turnability of the cast. More later. 
Do a good turn daily!
Don


> _Originally posted by thetalbott4_
> <br />Don-
> 
> Your casting looks great. Perfectly clear! Are you bringing the pot to 60 psi and then sealing it off with a valve, or leaving it hooked to the compressor? Pressure for entire cure time? As you lower your drops per ounce of catalyst, are you experiencing "sticky" or "tacky" castings? The first set I did are sticky on the exterior but seem to turn ok. Again, nice job!


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## PenWorks (Dec 28, 2005)

I guess everything is just bigger in Texas [] I just saw a picture of Serge's pot, more like a saute pan he stole from the wife's kitchen [] His sea snake came out just like yours crystal clear. you guys are onto something...... Good job.


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## JimGo (Dec 28, 2005)

Don,
I tried looking through HF for a paint pot, but didn't find one.  Still searching...

Never mind.  Of course, just after I post this, I find this...
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=93119

and this
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=37515

The later seems the better choice (and looks an aweful lot like yours Don!).


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## its_virgil (Dec 28, 2005)

I don't know what the difference is. There is a pick-up tube screwed into the under side of the top aht goes all the way to the bottom to suck up the paint. The pick up tube needs to be reomved and the hold on the top plugged. All threads are 1/4 NPT so fittings are found at any place that sells pipe fittings. I did not use the regulator and scuh that came with the pot. I could not keep it fropm leaking. I just used a brass pipe nipple, a tee, an air hose fitting and the guage. Plug in the air hose, watch the guage and remove it at 55-60. I left the resin in the tank all night because I cast it late, but it cures quickly and could probably be removed after and hour or two. The bubbles are crushed in size and rendered invisible. I think if the pressure were released too soon...while the resin is in the jell stage...the bubbles would expand and our efforts to eliminate them would be worthless. The pressure needs to be left on until the resing is totally cured. Just my thoughts. I'm doing a second cast tomorrow.
Do a good turn daily!
Don




<br />





> _Originally posted by JimGo_
> <br />Don,
> I tried looking through HF for a paint pot, but didn't find one.  Still searching...
> 
> ...


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## Darley (Dec 28, 2005)

> _Originally posted by PenWorks_
> <br />I guess everything is just bigger in Texas [] I just saw a picture of Serge's pot, more like a saute pan he stole from the wife's kitchen [] His sea snake came out just like yours crystal clear. you guys are onto something...... Good job.



Anthony please dodn't say anything to the Miss if not I will be nail to the wall [][][xx(]
Pressure casting working really good, I did mine in a pressure cooker and tested to 50 PSI but will not go futher to dangerous, Don pot in the way to go and it go up to 70 psi I think, here's the photo of my pot and my casting

edit == Pot photo deleted



<br />

To return to the original question ask by GaWoodworker casting natural snake skin is not a problem the problem when is dey you may have problem like I encounter when I cast leather fish skin and cane toad skin is about the chermical they use to tanner the skin, my casting was a total FIASCO PR when into the leater in pressure and I find myself with brass tube [][][xx(] will give another go

Conclusion no bubble at all for pressurised PR, is crystal clear when you turn filaments are a little bit longer than corian ( remember corian is cast under pressure too ) here's my pen  " Australian sea snake skin " 



<br />


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## GaWoodworker (Dec 28, 2005)

I noticed that you are using paper clips to hold the tubes in place. You don't seal the ends? I have been sealing my tubes to keep the resin out. Are you able to get the resin out of the tubes easily?


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## TexasJohn (Dec 30, 2005)

A couple of questions guys:  1) About how many blanks can you get out of one snake skin?  2) Is there a place that is better than any other to purchase the PR?  3)I am located at 4,000 ft. above sea level - how would that effect the process?  4)Is temp. a consideration? Warm better than cold? 5) Do you use CA to attach the skins to the tubes or epoxy?  Sorry to ask so many questions but this really looks like an interesting process. TIA for you response(s)  Texas John  [:0][?]


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## jpick22 (Dec 31, 2005)

After a visit from Don a few days ago (on his way to Bubbasville), He told me about the Pressure-pot.  I couldn't get to Harbor Freight fast enough and bought the same pot that someone here showed from HF.

Once I got the inner suction "tube" removed and sealed off and also the "out" side of the pressure gauge, I was ready to go.

I thought a bit about what the process was to be, according to Don's early experiments and decided to go about it a little differently. I decided that once the mold had reached the "gel" stage, that probably nothing more, change-wise would occur.  that is, there would probably be no more "compression" of the bubbles by that time.

Sitting out,(normal curing method), the gel generally takes place within 10 to 15 minutes, so I decided to apply the 60 pounds pressure for only an hour (just to be safe).  After an hour, I released the pressure and removed the mold.  It was PERFECT - bubble-free and clear.

The next mold was left in for 40-minutes.  Same result.  I've only done two thus far, but my next casting will be left for 30-minutes and if that works, I'll go down to 15-minutes.  Like I originally thought, once the pour has gelled, where is anything going?

By-the-way, (and I think Don already pointed this out), the top surface of your casting WILL ALWAYS BE STICKEY, REGARDLESS OF HOW LONG IT IS CURED. Just disregard this fact and go ahead and saw up your blanks after the blank has at least cured overnight - if the other surfaces are rock hard, you're ready to go.

And Texas John - "How many blanks can you make with a snake skin?"(or something like that).  Well TJ, how long is a rope?  Don't take me wrong, but no-one can answer that question.  But this will give you some idea.

I make only pens made on the slimline "chassis"  The tubes are 7mm in diameter.  This takes approx a 1" x 2" rectangle of snakeskin to wrap around the tubes (yes, most use CA to glue them down") This is just a point of reference, but just measure the diameter of your tubes and the length - then make a rectangle, using these measurements to determine the size of your snakeskin piece to be glued down - also, allow a 16" or so oversizing to allow for the "fold-over" necessary to hide the seam.  Hope that helps.

Jay


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## thetalbott4 (Dec 31, 2005)

Jay -

Thanks for the info. You are the man! I'm going to harbor frieght myself today for the paint pot. My wife caught me heading out of the kitchen with the pressure cooker and a few pots and pans and said NO.[V] Dang if she didnt encourage me to get the paint pot! Ilove it when a plan comes together.[]


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## its_virgil (Dec 31, 2005)

Texas John,
Some commercially tanned skins will go black when cast. I have tried my own tanned skins with some success and lots of work. I now purchase skins from Steve at http://www.sdsnake.com  He sells prairie rattlesnake skins from wyoming or montana and they work great. I posted a picture somewhere just a few days ago of some skins cast in a pressure tank. Jay just gave the details so I won't repeat them, but I will be  doing all of my casting in the pessure pot from now on. If you get some, get the smaller skins so the pattern will be smaller. I use the skins up to 30 inches or so. Steve knows what yuou will need. They cost 40 cents per inch, so a 30 inch skin will be $12 and should yield 6 or so pens per skin at 5" of skin per pen (only estimates). I would not think the altitude would affect the casting and I know it won't if you consider pressure pot casting. Temperature does since the chemical reaction produces heat and is necessary for curing. Casting in cold temperatures can take two days or more to cure. Jay Pickens has some great articles on the home page here. Be sure to read them...all you need to know is there. Here is a picture of my pot and the first snake skins from it.
Do a good turn daily!
Don



<br />



<br />


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## Darley (Jan 1, 2006)

Jay how much did you paid your pressure pot ? Don are they on sale now to HF?


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## wudwrkr (Jan 1, 2006)

I recently found a HF coupon and posted the information here: http://tinyurl.com/8yvj8 

With this, everything is on sale[]


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## TomServo (Jan 1, 2006)

I was reading some info on the sticky surface problems - and I can't remember where I found it.. next time I order resin, I'm going to try some of the surfboard resin, it is probably somewhat more flexible and durable than the casting resin.. Someone on here reported good success with it. Another option would be gelcoat resin - it should be the most durable, and scratch resistant as it's purpose is a topcoat.. 

I've found that by using 5-7 drops / oz and then heating the resin to about 120-140F, my blanks come out rock solid in 5-6 hours.. Left by itself, the resin exotherms to about 100F - and the surface ends up tacky/mushy about 1/16" deep..


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## TomServo (Jan 1, 2006)

aha! what do you know, seek and ye shall finde
not that this is really related to the topic at hand, but:

"This heat sink tendency creates a condition on the surface of the casting called surface degradation, (SD). SD is a sticky textured finish caused by a lack of exotherm on the surface of the casting. Preheating of the mold to 150 degrees F prior to casting will help to alleviate this condition."

http://www.fiberlay.com/howto/issue3.htm

more info - 

"Open molds. When using open molds, which are made from patterns with flat backs, some people pour resin into the molds and leave them  uncovered while the resin cures. I donâ€™t recommend this technique. Since modeling resins cure by heat, the air will prevent the top layer from getting hot enough, and youâ€™ll end up with a permanently sticky surface. Also, oxygen in the air inhibits some resins from curing, and the result is an even stickier surface." 

http://www.finescale.com/fsm/objects/pdf/resincasting1102.pdf

relating to the topic at hand: why not try coating the skin in epoxy, allowing to cure, sand the surface (to remove waxes!) and then cast? PITA but may help - casting epoxy is about 2-4x as expensive as PR, epoxy glue would work for this (some is clearer than others)

nth edit: 
"Materials that are dyed or painted should be tested for color fastness before casting embedding, as the color may bleed into the casting. Photographs, fabrics, paintings, prints and similar materials should be tested for compatibility with Clear-Lite resin before casting. Many items can often be sealed with Ultra Seal."
http://www.tapplastics.com/uploads/pdf/Clearlite%20Casting%20Tip.pdf

whatever this ultra seal stuff is, it may work on your skins..


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## GaWoodworker (Jan 1, 2006)

Wow, Tom! You did some homework and have provided a lot of good information. [8D]You get a gold star for today!


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## jpick22 (Jan 1, 2006)

Serge - I also got my pressure-pot at Harbor Freight, again at just under $80.

As a side note, this morning,I glued up enough snake skin for 5 pens (from one of the skins also bought from (can't remember) the same guy that Don mentioned earlier - this one was about 28" long.  I have a tail section of about 4" left, but with not much in the visually interesting, so I will probably just junk it.

I also took 2 of the sets (one long tube, one short tube, like in the Euro-type pen kits) out to the garage about an hour ago and put them into the pressure pot and believe me, it was really packed with a zillion bubbles (purposely).  I left it under 60 # pressure for 45-min.  When removed, it was fantastic - absolutely clear and free of bubbles. Thank you-Thank you, Serge and Don.  For my money, this has been one of the most incredible "finds" in the 3-1/2 years I've been in this racket - and I've been playing with polyester Resin for almost 3 years.  This new "product" is a real blessing for those of you who cast resin - and for those of you who plan to, a real "saver" of a lot of problems and headaches in your future.

Jay


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## its_virgil (Jan 1, 2006)

Tom,
Thanks for the info. But if the casting is for pen blanks, then the top surface that gets sticky witll be turned away and end up on the floor, so the sticky surface is not a problem. If, on the ohter hand, the casting is to be left intact, the the sticky surface problem needs to be addressed as you mention.

Also, I will say again that the skins I've purchased form http://www.snsnake.com have never turned dark on me. I've tried curing my own, purchased scraps from boot makers, and purchased from other sources and most all of those did poorly when embedded. I think it must have something to do with the curing chemicals. For the price and service from the above mentioned sdsnake.com, I will continue to purchase instead of trying to do my own. A 30" skin at 40 cents per inch is $12 and will yeild 6 or 8 pens. The price of the skins and resin is still far less than the cose of purchasing blanks already cast. Drawback is sdsnake.com only handles one species of snake, ...the prarie rattler form Montana or maybe Wyoming.

Also, I've tried coating skins with various materials from CA to epoxy to lacquer and if the skin wants to go black it went. It amazes me how a cured snake skin will turn black but the guys who print stuff on computer paper and embedd the print in PR and it works just fine. Go figure.... Casting PR is fun and its really nice when things work out. Thanks again for the info you supplied.

Do a good turn daily!
Don




> _Originally posted by TomServo_
> <br />
> 
> "Open molds. When using open molds, which are made from patterns with flat backs, some people pour resin into the molds and leave them  uncovered while the resin cures. I donâ€™t recommend this technique. Since modeling resins cure by heat, the air will prevent the top layer from getting hot enough, and youâ€™ll end up with a permanently sticky surface. Also, oxygen in the air inhibits some resins from curing, and the result is an even stickier surface."
> ...


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## its_virgil (Jan 1, 2006)

Serge, 
They are currently $79.95 and no they have no gone on sale, but I will keep an eye on their adds and let you know when it goes on sale if it does. Have you checked with the local paint stores to see if they have paint pots? If you know an older painting contractor maybe he will have one sitting around or may know of someone who does. We just need to be careful with what we use to pressure cast.


Anyone interested in casting resin under pressure, please read:
<b>A word of warning to those of you who are considering pressure casting. Having read on a couple of casting forums, everything I've found warns against casting in a pressure cooker. Pressure cooking often does not exceed 15 psi and to pressure cast, the pressure needs to be in the 40-60psi range. BE SURE YOU KNOW THE PRESSURE RATING ON WHAT EVER VESSEL YOU CHOOSE TO CAST IN. IT IS NOT WORTH INJURY TO GET THAT PERFECT CAST.[</b>

Now, lets have some fun and always practice safe casting.[]

Do a good turn daily!
Don



quote]_Originally posted by Darley_
<br />Jay how much did you paid your pressure pot ? Don are they on sale now to HF?

[/quote]


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## PenWorks (Jan 1, 2006)

I agree about the stickyness, you turn it off anyway, so that is no big deal. After a couple of days, it does harden.

I have not had the air bubble problems, but you guys are going to make me buy a paint pot, the way you keep talking about your clear castings []

Nice disclaimer Virgil, I never thought about Serge blowin the top off the Mrs. pot !

Happy New Year


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## Darley (Jan 1, 2006)

Don didn't find any pressure paint pot here and won't buy a used one, maybe in a bigger city $ 80.00 is a good buy just keep an eye on it.

Jay when I did the 1st casting I did stir the PR with and old fork to make as much possible bubbles and the result is the casting on page 2,I did some in time limit of 5 minutes under pressure with good result but left the casting in the pot undisturbed until cured, possibility is, if doing the PrCast ( Pressure Casting ) leave it 5 minutes under pressure then take it out of the pot and do more castings, the person may turn 100+ pens a day if he want ( when he build a shelve to go in the pressure pot ), when the bubbles a crushed down to none, maybe let cure the PrCast out of the pot on the bench

I will and do suport 100% Don comment about PrCast and therefor will delet the photo of my pot, I will start again PrCast when I will have the paint pot.



> Anyone interested in casting resin under pressure, please read:
> A word of warning to those of you who are considering pressure casting. Having read on a couple of casting forums, everything I've found warns against casting in a pressure cooker. Pressure cooking often does not exceed 15 psi and to pressure cast, the pressure needs to be in the 40-60psi range. BE SURE YOU KNOW THE PRESSURE RATING ON WHAT EVER VESSEL YOU CHOOSE TO CAST IN. IT IS NOT WORTH INJURY TO GET THAT PERFECT CAST.



Anthony what for tea tonight? ..........................Your answer " Rattle snake PrCast stew mate " []


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## woodman928 (Jan 1, 2006)

Dont be afraid of a used pot. I bought them at auctions from $10.00 to $100.00 and the were OK just look to make sure they are not rusted to bad you can take them to a paint sprayer company and have them cleaned and a new gasket install for 10 to 50 dollars. They are also a good place to look for used pots at a good buy. They can be paint pots or glue pots (they are the samething) you might find some old glue pots at cabinet shops that have upgraded to the pressure glue cans.
 Lowes sometimes has them cheap also.[]
Jay C.

Watch for auction of large woodworking or metal shops sometimes they have 10 to 20 gal pots that go realy cheap


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## TomServo (Jan 2, 2006)

Don: my concern with the sticky surface problem, is how do you know the center is fully cured? I don't ever want to have a PR blank come back because it got mushy from skin oils or something normally harmless... The first couple i did, never hardened up fully (there's still a mushy blank in my box) and the pen was a little soft after i turned it.. The ones i put on my aqarium light (it's a bit warm up there) to cure are rock solid, and have stayed that way except when i hit them with DNA.. There's probably nothing wrong with the blanks that come out sticky, but probably isn't such a great word... and i drill close to the edge on some blanks.

Part of the reason for my research, is also that I plan on using PR to coat my computer case when I build it. A sticky/not so hard surface isn't a great idea in this 'case'. I plan on using 2x2's and 1/4" birch plywood to make it.


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## its_virgil (Jan 2, 2006)

Not arguing with you, and I understand your concery. Every cast I've done was sticky on the surface that touched the air but were always cured hard all the way through. I have had some that never cured but I think I altered the chemistry by adding the wrong kind of colorant or too much of it. Most of what I cast are snake skins and they always cure rock hard. I have 4 or five colored casting and the pens are as hard today as they were 18 months ago when I cast them. I have my system and it is working for me. I think once the resin cures, there is no uncuring. Not trying to convert anyone, just relaying what I discover so we can all have fun casting and I know that is what you are doing also. And you gave some really good information. Happy casting.
do a good turn daily!
Don


> _Originally posted by TomServo_
> <br />Don: my concern with the sticky surface problem, is how do you know the center is fully cured? I don't ever want to have a PR blank come back because it got mushy from skin oils or something normally harmless... The first couple i did, never hardened up fully (there's still a mushy blank in my box) and the pen was a little soft after i turned it.. The ones i put on my aqarium light (it's a bit warm up there) to cure are rock solid, and have stayed that way except when i hit them with DNA..


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## GaWoodworker (Jan 2, 2006)

> _Originally posted by TomServo_
> <br />Don: my concern with the sticky surface problem, is how do you know the center is fully cured?



Fortunately, I have never had a piece that has not had a mushy center. I  use the small amount of resin that remains after I pour as my guide to the state of curing. Leave it in a wax cup or pour it into an empty mold. If it is rubbery, I know it hasn't cured but if it is rock hard, the resin in my castings will also be rock hard.

To this point, I have not had a skin prevent curing. I have had them turn, but not hinder curing. Those from the Snake Den are safe, but I'm sure it is possible that other methods of sealing skins could have a coating that might cause defective curing. Sometimes the skins from the Snake Den are fairly oily as if they were newly preserved. I leave them out in the air for a week or so and they always dry out fine.

Your research was great. You provided a lot of valuable information that I found to be very helpful. Thanks for all the work you shared with this group!


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## TomServo (Jan 2, 2006)

Thanks! it wasn't that hard to find, really.

One question: (for don perhaps) did the skins turn black when you coated them with epoxy, or later when you encapsulated with PR?


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## its_virgil (Jan 2, 2006)

GaWoodworker,
The thinner the cast the longer it takes to cure. The small amount of left over resin will take longer to cure than your pen blank cast. Thin castings build up less heat. That's why the amount of catalyst used changes with the thickness of the cast...according to the directions on the can. It's not rocket science, but it is some kind of sciece. The sticky surface does not alter the curing time as far as I can tell.
Do a good turn daily!
Don


> _Originally posted by GaWoodworker_
> <br />
> 
> 
> ...


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## its_virgil (Jan 2, 2006)

Tom,
The ones that turned black turned after the resin was added. I think it is more the heat and the tanning chemicals, but as thick as that resin is, it must thin out when the heat starts because it can seep throug the smallest of cracks. When I've thought I've had the ends sealed with wooden plugs and sealed with CA, the stuff still has managed to leak inside the tubes. Maybe my epoxy coatings were too thin or had a breach in them. But, the skins from sdsnake.com have never turned dark...not once. 
Do a good turn daily!
don


> _Originally posted by TomServo_
> <br />Thanks! it wasn't that hard to find, really.
> 
> One question: (for don perhaps) did the skins turn black when you coated them with epoxy, or later when you encapsulated with PR?


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## GaWoodworker (Jan 2, 2006)

> _Originally posted by its_virgil_
> <br />GaWoodworker,
> The thinner the cast the longer it takes to cure. The small amount of left over resin will take longer to cure than your pen blank cast. Thin castings build up less heat. That's why the amount of catalyst used changes with the thickness of the cast...according to the directions on the can. It's not rocket science, but it is some kind of sciece. The sticky surface does not alter the curing time as far as I can tell.
> Do a good turn daily!
> Don



I'm not sure I understand the point you are trying to make? Are you responding to one of the post about sticky surfaces or am I overlooking what you are trying to say?[8)]


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## its_virgil (Jan 2, 2006)

GaWoodworker,
Maybe I'm confused. You said: Fortunately, I have never had a piece that has not had a mushy center. To me this means that all your centers are mushy, but I don't think that is what you mean because you began with the word Fortuanately.

You said: I  use the small amount of resin that remains after I pour as my guide to the state of curing. Leave it in a wax cup or pour it into an empty mold. If it is rubbery, I know it hasn't cured but if it is rock hard, the resin in my castings will also be rock hard. My comment is that the thinner the cast or the thinner the resin thickness the longer it takes to cure. So, when the thin left over amount is cured, the real casing should have long ago cured. Thick = faster curing and thin = slower curing because of the heat. 

You said:To this point, I have not had a skin prevent curing. I have had them turn, but not hinder curing. I thought I replied that the skins have not hindered the curing for me, they just turn black or dark and you can't tell what is in the casting. 

You said: my concern with the sticky surface problem, is how do you know the center is fully cured? My response: the surface exposed to the air is always sticky(unmless you do something to prevent it). Why do anything to prevent the sticky surface for pen blanks...it will be turned away and end up on the floor. How do I know it is cured? It will be hard. I don't think it will cure partially i.e cure 3/4 in thick all the way around and leave 1/8 inch uncurred in the center. I have never turned a home cast blank that was uncurred in the center. If they seem to be a little pliable, I set them aside for a few days and they harden. I have had a few that never cured and I think that was due to the colorant I used that screwed up the chemical reaction and after three weeks it was still not cured. 99% of what I cast is cured with an hour or sooner and I turn it the next day. Have had no problems with uncurred centers.

I hope this helps and sorry about the confusion. We had two topics going in this thread....skins turning black and the sticky surface and curing.

Do a good turn ldaily!
Don


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## Darley (Jan 2, 2006)

> _Originally posted by TomServo_
> <br /> except when i hit them with DNA..



Why would you use DNA on, with, in PR casting?


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## Darley (Jan 2, 2006)

I find this site for people who are concern about PR sticky surface after curing, scroll down to 3/4 page and you have a product for it, but I my regards will not buy like Don say you turn it away

http://tinyurl.com/9vea3


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## GaWoodworker (Jan 2, 2006)

> _Originally posted by its_virgil_
> <br />GaWoodworker,
> Maybe I'm confused. You said: Fortunately, I have never had a piece that has not had a mushy center. To me this means that all your centers are mushy, but I don't think that is what you mean because you began with the word Fortuanately.
> 
> ...



Ahhh. I mistyped. I meant that <b>I have never had a piece that has had a mushy center.</b> One little <s>not</s> can make a big knot in my post  

[:I]


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