Pouring Decoy Anchors

Eric Patterson

Eric Patterson

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Staff member
For a number of years I've been pouring my own anchors. I've made my own molds from oak and have bought aluminum molds as well. Much of what I pour is sinker type weights for Texas rigging so lead purity isn't real critical. Tire weights and other lead scrap are fine for these anchors and I've made hundreds of them without issue.

Strap anchors (the ones that bend around a decoy's neck), on the other hand, are now the bane of my existence. They are giving me fits. To get nice looking straps I've gone to heating the mold to the lead melting point, pouring, letting it all cool and then prying the anchor free. They are nice and uniform. Without pre-heating the mold the lead solidifies too fast and the straps have a lumpy bumpy side on the exposed pour side of the mold.

However, the problem isn't looks, it's cracking when used. All my pours result in straps that after bending a few times begin to crack. My theory is the lead cracking issue is a result of lead impurity. I ran an experiment yesterday to test this theory. I sacrificed some store bought flexible non-cracking straps into a clean pot and poured three straps. After they cooled I gave them the bend test and sure enough after four or five bend cycles they began to crack. Why? I used proven lead. Is the lead oxidation process present when open pouring contaminating the lead? Something else perhaps?

Anyone here have a proven process to make strap anchors that stay soft and bendy over time? If I can't figure this out I'll buy my straps and pour the rest, but dang, I thought it wouldn't be this challenging.
 
I pour my own anchors and fishing weights. I use H style decoy anchors, I haven't used strap weights so keep that in mind.

My experience is that any alloys or impurities in the lead make it susceptible to cracking. If you can find a source of pure lead, no tin or antimony, it will probably help. Even H anchors break if the lead isn't right. I had about a hundred anchors from one casting party that have all disintegrated. They fall apart into four or five pieces, something in them makes them quite brittle. Battery plate always seems to contain crap that contaminates the pour.

The other consideration, which I have never mastered, is temperature of the pour. Some of my friends have and the better quality of their anchors and weights is obvious. I don't understand precisely how temperature effects the product, maybe there's something about it online.
 
SJ

I think there is more to it than initial lead purity. Like I mentioned, I melted some soft strap anchors who I knew were from good lead and re-poured them. They cracked. I sandblasted my pot to rid it of contaminants and yet the anchors from known good lead still cracked when stressed. Maybe temperature has something to do with it. Maybe oxidation from being exposed to air contaminates the lead. I don't know, but I've yet to pour a strap anchor I'd tie on a decoy.

Appreciate your input. Might be time to google.
 
Eric Patterson said:
SJ

I think there is more to it than initial lead purity. Like I mentioned, I melted some soft strap anchors who I knew were from good lead and re-poured them. They cracked. I sandblasted my pot to rid it of contaminants and yet the anchors from known good lead still cracked when stressed. Maybe temperature has something to do with it. Maybe oxidation from being exposed to air contaminates the lead. I don't know, but I've yet to pour a strap anchor I'd tie on a decoy.

Appreciate your input. Might be time to google.
Click to expand...
If you can locate a foundry in your area, ask them. Here in CT there are virtually none left because of environmental rules.
 
Eric Patterson said:
SJ

I think there is more to it than initial lead purity. Like I mentioned, I melted some soft strap anchors who I knew were from good lead and re-poured them. They cracked. I sandblasted my pot to rid it of contaminants and yet the anchors from known good lead still cracked when stressed. Maybe temperature has something to do with it. Maybe oxidation from being exposed to air contaminates the lead. I don't know, but I've yet to pour a strap anchor I'd tie on a decoy.

Appreciate your input. Might be time to google.
Click to expand...
Checking with my daughter, the metalurgist.... I know that slow cooling results in large grains in the material. Larger grains will be weaker for bending fatigue.
 
Dave

I think you are on to something. When the lead cracks I observe a hairy grainy texture in the crack. Fast cooling may solve that, but other than water, which has no place near molten metal, I'm not sure how to accomplish it.
 
Perhaps. I wish I could find a hinged strap mold. It would be easier to handle and move around in order to cool. An open mold like the one I have is a just a pool of molten lead making it hard to move around without spilling or making lumpy and bumpy.
 
In my own experience, my weights would become brittle and week when I heated my lead too hot. If I keep the pot on high heat after it melts, the weights are kinda brittle. After my lead is all liquid, I turn down the heat. If it starts to harden up, I up the heat. It's not too difficult to find the sweet spot.
I use a 2 gallon pot, on a propane burner.
 
Eric Patterson said:
Dave

I think you are on to something. When the lead cracks I observe a hairy grainy texture in the crack. Fast cooling may solve that, but other than water, which has no place near molten metal, I'm not sure how to accomplish it.
Click to expand...

You have to balance the temp - hot enough mold to get a good pour, but not have the mold so hot that the lead cools slow enough to crystalize.
 
The purer the lead the better for making the strap style weights. When my dad was employed as the head of a DP department at a hospital he would have the shipping department save the lead containers that the radioisotope was shipped in for the radiology department. We made all our decoy weights and fishing weights from them when I was in highschool. When we went from a pothole blind to a river blind we put out around 250 to 300 decoys between 3 hunters. We used a 2" ladle and wire coat hangers for the weights heavy enough for the river current. Sorry, got a little long winded. Some good memories.
 
FWIW, I just put some "new"--as in been in the duck cave end of the barn a long time, but purchased new and not previously used--strap anchors on some George Soule decoys I found. One bend around the neck after a single use and strips were peeling off the anchors at the long edges. No issues with some others put on at the same time that were old beat up salvaged straps.
 
First, I've not tried pouring strap anchors, I have worked with lead for a lot of years tho. For pure lead, check with the local PD to see if they'll let you into their indoor firing range, hopefully when they aren't using it... a lot of paper, copper and wads to clean up but good soft lead, the other thing is the look up an asbestos/lead abatement contractor. I've gotten some clean 1/8" thick sheets of lead from my local guy. Just sheared pieces to the size I wanted. Temperature has been mentioned, To me, if the lead changes color AT ALL it's too hot, plus that is when you start inhaling vapor. Smoking the mold hasn't been mentioned, Invert the mold and hold a lit candle close to the cavity until its completely coated with candle soot. The soot acts as a lubricant to move the lead faster and as an insulator to keep the lead liquid a bit longer. There are products to help clean impurities out of the liquid lead but a chunk of candle wax stirred into the pot works as a flux also.
Damn, that's the most I think I've ever said here....

George
 
Hi Eric, nice challenge. First off I've never tried casting anchor straps but can certainly see where the extremely high ductility requirement would be hard to achieve for a home caster. Purity and grain structure are going to be critical.

Purity, Unless you're purchasing lab certified pure lead it's a crap shoot. I was lucky enough to get a lot of lead conduit that was used by the phone company for shielding underground wires in the good old days along with some lead shower pans from renovations of older homes.

Cleaning: while we're talking purity, all lead that's been exposed to the atmosphere has a layer of lead oxide that is an undesired contaminate. (think painting or welding aluminum) The longer and higher humidity of that exposure, the thicker the layer. So even pure lead needs cleaning when reusing it. IMHO this cleaning step should be totally separate from your casting step. This allows a lot more flexibility in getting the scrap melted, cleaned and fluxed efficiently. And by casting this cleaned material into ingots, you'll have clean, uniform ingots for charging your pot while casting your anchors, helping to keep the temperature in the sweet spot for the precision required for your strap anchors, bullets and jigs. Larger items are probably more easily done in a single shot. I've found large cast iron pots and propane burners to be much better for reclaiming lead. Lots of room for inserting odd shapes and loads of
BTUs to get the job done. Bottom pour, electric pots provide better control for precision castings up to a pound. Larger castings can be poured but the pot won't provide enough heat to allow recharging while casting. You'll have to stop every few castings to allow the pot to catch up.

Fluxing: is critical to get the lead oxide out, even with you previously cleaned ingots. Once the lead is melted add a bit of candle wax to the pot and it should light off into a burning layer on the molten lead. (If it doesn't light off, add a bit more and help it with a wooded match or propane torch) While it's flaming, stir the pot with a large spoon/scraper to get the oxide off the sides and bottom of the pot. It will float to the surface to be skimmed off. Depending on your casting methods and rate of recharging, you may need to flux occasionally as you're casting.

Temperature: Lead melts at 620 - 625 F Target temperature for casting is 630 - 650 F. The higher the temperature above this, the grainier the lead casting. I know bullets cast at higher temperatures look frosty due to the rough surface. My low precision casting has always been controlled by adding more lead if it seems to be too hot and if it starts to thicken due to too much lead slow down on casting until its flowing better. I now have an infrared thermometer (laser temperature gun) that I haven't yet tried on molten lead but might work well.

Annealing/stress relieve: Not real sure about this, but it's worth a try. My recommended first shot - Heat to 450F for 20 min and air cool. General Google results aren't to promising but most of the posts are looking at increasing strength/hardness not improving ductility.

Mold prep: Referencing George's post, smoking the inside of the mold with a candle is a good old school method using the carbon layer to help release the casting from the mold with minimal damage.

Mold preheat. Definitely required with cast iron molds and can be helpful with aluminum molds. Generally with aluminum molds you can pour the first and possibly the second round and dump them back into the pot to get the mold up to casting temperature. The purpose of the preheat is to prevent flash freezing the lead and screwing up the flow through out the mold. More critical in closed molds as open molds allow the lead to be added do the length of the mold rather than in a single sprue location.

Hope this gave you some ideas, good luck!
Scott
 
Scott

When I posted this topic I thought you might have some insights. I was not disappointed. You've given me some ideas on things to try. Excellent info and thanks.
 
When I was young we did make our own weights but as I got older and my older kin passed away. It kind of died off but a few years ago I got back into making my own.

Tried making H weights and tried making strap type weights and just never could get good consistent results. Like we did when I was younger. Guess my grandfather keep a few secrets lol.

Anyways what I ended up doing was making my own J weight mold.

When I got back into making my own weights, was because the J type keel grabber weights had gotten so expensive. I have found that, I basically cant mess up on the J weights.

I have used them all. H, strap type and even egg shape on Texas riggs and I just prefer the J type keel grabber weights.

Couple of friends and family like to complain come setup/pick up time. But I just point out my 10 year old decoys still look better then their 2 year old decoys they bash around the floor board of the boat with Texas riggs 😂😂😂
 
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