- Joined
- Feb 24, 2005
- Messages
- 1,669
- Reaction score
- 183
- Points
- 223
- Location
- North of Boston, USA
- Printer Model
- Canon i9900 (plus 5 spares)
Rob - I bought a few stainless steel screws at Ace Hardware ($0.20/ea.), and was pleasantly surprised to find that they were not magnetic (there are some low chrome content "stainless steels" that have poor corrosion resistance and are magnetic). I put one of them and a zinc plated screw in a sample of ink and left them for 4 days. On pulling them out of the ink and washing them off, this is what I saw:
The zinc plating did a good job where it was plated, but it is obvious that the plating didn't extend completely to the tip of the screw. This isn't a real problem in "normal" applications, where the screw tip isn't exposed (or seen). Actually, this shouldn't be surprising, as it is necessary to hold the screw somehow while it is being plated. It looks like it is held at the tip, so this area doesn't get plated.
I'll obviously be replacing my zinc plated screws with stainless steel screws.
Bobglen97 - This is definitely OT, but there is a little more to the muffler rust-out issue than just stainless steel. At least in the US, automakers have to guarantee that the emission system will meet the emission standards for 50,000 miles. Since the catalytic converter is part of this system, the auto makers now had an incentive to make sure that the exhaust system lasted for more than a year.
A second major change was that tetraethyl lead was removed from the gasoline at the same time because it fouled the catalytic converters. When tetraethyl lead was used, the gasoline companies had to add compounds with such things as bromides to keep the lead residue from building up on the valves, etc. The fun began when a car was started with a cold exhaust system. Water from the combustion process condensed inside the muffler (this is what runs out of the tailpipe of a cold car, not raw fuel) and mixed with the bromides to form such nasty things as hydrobromic acid (http://ptcl.chem.ox.ac.uk/MSDS/HY/hydrobromic_acid.html). If the car was driven long enough to heat the exhaust system and dry it out, this wasn't a big problem. If the car was only driven a short distance, the acid would remain in the exhaust system and quickly eat it out. This is why "short hops" are so hard on a car, even if they are less of a problem now than they used to be.
The zinc plating did a good job where it was plated, but it is obvious that the plating didn't extend completely to the tip of the screw. This isn't a real problem in "normal" applications, where the screw tip isn't exposed (or seen). Actually, this shouldn't be surprising, as it is necessary to hold the screw somehow while it is being plated. It looks like it is held at the tip, so this area doesn't get plated.
I'll obviously be replacing my zinc plated screws with stainless steel screws.
Bobglen97 - This is definitely OT, but there is a little more to the muffler rust-out issue than just stainless steel. At least in the US, automakers have to guarantee that the emission system will meet the emission standards for 50,000 miles. Since the catalytic converter is part of this system, the auto makers now had an incentive to make sure that the exhaust system lasted for more than a year.
A second major change was that tetraethyl lead was removed from the gasoline at the same time because it fouled the catalytic converters. When tetraethyl lead was used, the gasoline companies had to add compounds with such things as bromides to keep the lead residue from building up on the valves, etc. The fun began when a car was started with a cold exhaust system. Water from the combustion process condensed inside the muffler (this is what runs out of the tailpipe of a cold car, not raw fuel) and mixed with the bromides to form such nasty things as hydrobromic acid (http://ptcl.chem.ox.ac.uk/MSDS/HY/hydrobromic_acid.html). If the car was driven long enough to heat the exhaust system and dry it out, this wasn't a big problem. If the car was only driven a short distance, the acid would remain in the exhaust system and quickly eat it out. This is why "short hops" are so hard on a car, even if they are less of a problem now than they used to be.
, including the shipping charges to Miami.
