madmike Posted June 29, 2009 Share Posted June 29, 2009 Found this informative article whilst browsing. Worth thinking about. Lead + CA glue: a dangerous combination A great website by the way. MikeJ Quote Link to post Share on other sites
Grant in West Oz Posted June 29, 2009 Share Posted June 29, 2009 Intriguing. That's not an issue I've encountered with nose-weights. Nor even in assembly of white metal parts, less lead in the alloy I guess. I must say I tend to set my nose weights in place with blue-tac. A product I've seen remain inert in the modelling situation for a number of years, closing on 18 at least. Perhaps the lead was older flashing material with substantial surface oxidisation or even a surface coating? The comment re: no lead or lead based paint for museum models, is imo, just 'nervous-nellie' political correctness. G Quote Link to post Share on other sites
Big Kev Posted June 29, 2009 Share Posted June 29, 2009 I've fixed lead fishing sinkers into the nose of tricycle aircraft with Blu-Tac too, and it works very well. I once had smoke pouring out of a model when I used too much CA to fix some weights with, and hit it with too much accelerator! Never again... Kev Quote Link to post Share on other sites
pigsty Posted June 29, 2009 Share Posted June 29, 2009 The comment re: no lead or lead based paint for museum models, is imo, just 'nervous-nellie' political correctness. It's not, it's just silly over-cautiousness. The most likely culprit is their insurers. This shouldn't be a problem if you use fishing weights, since they don't contain lead. The problem with smoke from CA + accelerator may be heat rather than a chemical reaction - although, never having used accelerator, I can't be sure. With all that said, using white glue is a good tip, if only because it's less brittle than CA. I bashed my P-3 after I'd added the weights and closed the fuselage, and now I have to take three or four attempts to settle it on its nosewheel because one or two of the weights have gone walkabout inside ... Quote Link to post Share on other sites
72linerlover Posted June 29, 2009 Share Posted June 29, 2009 Hi, all Normally, as far as it is possible, I prepare some lead sheets, degrease and clean them with alcohol, glue them in a pack with epoxy and seal around with epoxy too. Then fit into the recesses I prepared before and glue again with epoxy. Better epoxy than CA because it fills every gaps and doesn't create fumes. More health for your model and for you. Regards Euge Quote Link to post Share on other sites
Grant in West Oz Posted June 29, 2009 Share Posted June 29, 2009 It's not, it's just silly over-cautiousness. The most likely culprit is their insurers.This shouldn't be a problem if you use fishing weights, since they don't contain lead. The problem with smoke from CA + accelerator may be heat rather than a chemical reaction - although, never having used accelerator, I can't be sure. With all that said, using white glue is a good tip, if only because it's less brittle than CA. I bashed my P-3 after I'd added the weights and closed the fuselage, and now I have to take three or four attempts to settle it on its nosewheel because one or two of the weights have gone walkabout inside ... Sinkers as we call em in Oz, are still lead or lead alloy. Heat generated in curing ca glue is a chemical reaction with atmospheric, or applied moisture. One of our club members did a tutorial on how to make a custom fitted nose weight using lead, pot-metal or antimony. Balance the model slightly aft of the main wheels, fill a medicine cup with the amount of metal needed to keep the nose firmly down. He then pressed wax into the available spaces of the model and cooled it. Then made a plaster of paris mould with the wax in place. Allow the plaster to dry completely. When dry, heat the cast sufficiently for the wax to depart, leaving a hole. Into which he poured the pre-measured amount of now molten metal. Bust 'er open, and there's your fitted nose-weight. G Quote Link to post Share on other sites
Mr Sworld Posted June 29, 2009 Share Posted June 29, 2009 Wow, the airliners are really going for thick 'anti'terrorist' doors on the cockpit nowadays! :D Quote Link to post Share on other sites
72linerlover Posted June 29, 2009 Share Posted June 29, 2009 Wow, the airliners are really going for thick 'anti'terrorist' doors on the cockpit nowadays! :D Ha Ha! Good suggestion! The vertical ballast is placed where seated the flight engineer between two bulkheads, fortunately not visible from outside. Euge Quote Link to post Share on other sites
Triarius Posted June 29, 2009 Share Posted June 29, 2009 The problem with lead and CA resulting in an expansion is due to formation of lead corrosion product, still sometimes known as "white lead" (or "sugar of lead" before chemistry became standardized.) White lead forms on exposure to atmospheric moisture if even tiny amounts of any ionic compound (the salt from a fingerprint will do it) are present. It is hygroscopic, meaning that it will adsorb more water and swell when the humidity is high, then shrink when humidity drops by giving up water. Further formation of white lead, followed by the same swelling/drying cycle, causes increased expansion. CA polymerization involves water molecules, which I think become part of the matrix (I haven't studied the chemistry enough to be sure), and CA is slightly hydrophillic (meaning it attracts water molecules.) Note that most CA does not do well when continuously soaked. I speculate that the CA polymer also provides a sufficiently ionic environment at the lead/CA interface to promote corrosion. I have seen white glue produce some corrosion on lead, but not as much. As a final note, this form of lead oxide (white lead) is highly soluble, can be absorbed through the skin, and is highly toxic. I always use 5 minute epoxy=no worries. Quote Link to post Share on other sites
Av8fan Posted June 29, 2009 Share Posted June 29, 2009 That was a really nice build. I noticed that some of the local shops are carrying Bismuth non lead sinkers. I think I will switch to those. Thanks for the info everyone. Quote Link to post Share on other sites
Neo Posted June 30, 2009 Share Posted June 30, 2009 Ive actually had some problem with this in the nose of my p-38 it deformed my nose a little the plastic melted inwards kinda weird.. i masked it up as battle damage!! Neo Quote Link to post Share on other sites
richter111 Posted June 30, 2009 Share Posted June 30, 2009 I super glue pennies together, then tack glue them into the nose or cowling, thankfully I have not had any problems. Thanks for the heads up on the lead sinker issue Quote Link to post Share on other sites
Big Kev Posted June 30, 2009 Share Posted June 30, 2009 The problem with smoke from CA + accelerator may be heat rather than a chemical reaction - although, never having used accelerator, I can't be sure. Oh yeah, it was definitely heat - nearly melted the fuselage! I still reckon Blu-Tac (or some other form of putty) is a safer bet than any type of glue these days. I've got at least one model with an annoying rattle from a fishing sinker come loose... Kev Quote Link to post Share on other sites
Phantom ordie Posted June 30, 2009 Share Posted June 30, 2009 Try tungsten weights,they are smaller with the same weight as lead. Quote Link to post Share on other sites
madmike Posted July 1, 2009 Author Share Posted July 1, 2009 I use fishing sinkers and wood glue (PVA) in the main MikeJ Quote Link to post Share on other sites
pigsty Posted July 1, 2009 Share Posted July 1, 2009 Oh yeah, it was definitely heat - nearly melted the fuselage! I still reckon Blu-Tac (or some other form of putty) is a safer bet than any type of glue these days. I've got at least one model with an annoying rattle from a fishing sinker come loose...Kev I should have said, heat caused by the curing of the CA, rather than a direct chemical reaction between it and the plastic. Any one-part glue that bonds rather than dissolves should be fine; two-part glues are better avoided because they too produce heat as the two parts react (although I've never had too great a problem using epoxy for long seams). Having said that, Blu-Tack is inert and has the advantage of weight, so if you can't fit your weights into a space or you run out, it's a good substitute. Where on earth would you find tungsten weights? And another thought: what's used to make the weights that balance car wheels after you've had your tyres fitted? Quote Link to post Share on other sites
Grey Ghost 531 Posted July 1, 2009 Share Posted July 1, 2009 (edited) I use bird shot and epoxy. The epoxy pretty much encapsulates the lead - I haven't had any problems yet. I had to look up the weight of tungsten. I didn't realize it was that heavy: lead is 11.35 g/cc, tungsten is 19.3! close to twice the density. Edited July 1, 2009 by Grey Ghost 531 Quote Link to post Share on other sites
William G Posted July 1, 2009 Share Posted July 1, 2009 Well at first I thought this was going to be specific to the fact that CA can get hot enough to cause the lead to transfer to the surrounding air... I have been using lead weights with everything from wood glue, CA, epoxy, clay and even using that good old standby White Glue, and never had any issues. On the other hand I have had issues with the glues not staying in place and shrinking causing the weight to pop free... Yep Dave, lead shot is a great combo. Prefer it with a nice slow setting epoxy. I always test the epoxy first on a sheet of thin plastic to see if it generates heat that way I dont get the deformed sections... William G Quote Link to post Share on other sites
northeaste36 Posted July 1, 2009 Share Posted July 1, 2009 I use bird shot and epoxy. The epoxy pretty much encapsulates the lead - I haven't had any problems yet.I had to look up the weight of tungsten. I didn't realize it was that heavy: lead is 11.35 g/cc, tungsten is 19.3! close to twice the density. You know tungsten is the metal of choice for the frag part of blast/frag type weapons, everything from A2A missiles to man-portable devices of all kinds. Quote Link to post Share on other sites
pigsty Posted July 1, 2009 Share Posted July 1, 2009 You know tungsten is the metal of choice for the frag part of blast/frag type weapons, everything from A2A missiles to man-portable devices of all kinds. Kinder than depleted uranium, too ... though I'm not sure I'll be relying on AIM-120 warheads for my supply of balance weights! Quote Link to post Share on other sites
Av8fan Posted July 1, 2009 Share Posted July 1, 2009 I was trying to find some tungsten locally. I found companies that do tungsten fishing weights. Good gosh the cost.. Quote Link to post Share on other sites
Grant in West Oz Posted July 2, 2009 Share Posted July 2, 2009 Atomic weights: lead-Pb=207.19 Tungsten-W=183.85 Bisthmuth-Bi=208.98 Bisthmuth is heavier and cheaper than tungsten (Wolfram). Quote Link to post Share on other sites
Triarius Posted July 2, 2009 Share Posted July 2, 2009 Atomic weights:lead-Pb=207.19 Tungsten-W=183.85 Bisthmuth-Bi=208.98 Bisthmuth is heavier and cheaper than tungsten (Wolfram). b-i-s-m-u-t-h ;) IIRC, tungsten is used because it is both harder and has a significantly higher tensile strength than either lead or bismuth, making it a better choice for armor penetration. Quote Link to post Share on other sites
Grey Ghost 531 Posted July 2, 2009 Share Posted July 2, 2009 Atomic weights:lead-Pb=207.19 Tungsten-W=183.85 Bisthmuth-Bi=208.98 Bisthmuth is heavier and cheaper than tungsten (Wolfram). The atomic weight may be higher but the density of the metal is less that either lead of tungsten. Bismuth's specific gravity is only 9.75 g/cc Quote Link to post Share on other sites
northeaste36 Posted July 2, 2009 Share Posted July 2, 2009 This would have to do with the way a group of the specific atoms arrange together or what? Quote Link to post Share on other sites
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