Weldon warning - shelf life

[JohnK]

To those of you who like to tinker with acrylic DIY, and those who are consdiering it....

Weldon #3 / #4 definately have a shelf life. I have always trusted the local suppliers to rotate their stock or otherwise sell products that are not beyond their shelf life. Well I was wrong.........

I picked up material and a fresh can of WO#4 last week from a trusted boston supplier. Upon assembly of the frag tank I was hoping to build I found that every single seam came out terrible, so much so that I don't feel that I could trust the tank to hold water OR not explode.

After much second guessing of my techniques (i have built sumps, Ca reactor, and other projects in the past and never had a serious problem), I happend to notice that the cans are dated on the bottom. My fresh can Of WO#4 was dated mar 2009.

After continued second guessing of myself and some research I decided to pick up new acrylic sheet and find some fresh WO#4. Picked them up at the other Boston supplier today - WO dated jan 2011, seams perfect on the first try using the exact same techniques.

Conclusion - buyer beware and check the date on the bottom of the cans. Don't buy or use WO if it's more than a year old. The $5 can of solvent doesn't sound like a big deal, but it is when it ruins $80 of material and wastes 2 plus hours of prep time.

Hopefully this saves someone from going throught the same aggravation, wasted money and wasted time.

 

[HuuTa]

would WO work on a acylic and pvc to weld them together since they are both plastics?

 

[Pat02026]

Good call posting this John. Sorry to hear about the lost time/materials. I have yet to tackle a full out acrylic project, aside from siliconing in sump baffles. I have been waiting for a good project to come up to give it a shot and I will have to be sure to check the date. Is that a MFG date or expiration on the can?

 

[JohnK]

Not very well. Both are plastics, but not very similar at all beyond that.

WO#16 will do it, but it's messy and no where as strong as an acrylic to acrylic joint bonded together.

IIRC WO#40 or #42 may be better for PVC to acrylic, but I'm really not sure and have no exp with those.

It is possibly to drill and tap acrylic, and then install threaded PVC fittings. Using uniseals would be far easier and probably at least as effective.

 

[JohnK]

Good call posting this John. Sorry to hear about the lost time/materials. I have yet to tackle a full out acrylic project, aside from siliconing in sump baffles. I have been waiting for a good project to come up to give it a shot and I will have to be sure to check the date. Is that a MFG date or expiration on the can?

I beleive it's a mfg date. Luckily it was a fairly small frag tank I was building, so I'm only out about $80 and a few hours of my time. I probably would have been tempted to "go postal" if it had been a display tank and hundreds or even thousands of $$s wasted.

On a side note, I do plan on repairing the frag tank by guesseting all the seams. It'll look pretty crappy around the edges but be totally functional. Anybody want a great deal on an ugly frag tank?

 

[Pat02026]

Having no experience with the product myself, could you run a bead on the inside corners of the seams with a thicker based (if I understand correctly there's different viscosities) WO much like silicone in a glass tank?

 

[JohnK]

Having no experience with the product myself, could you run a bead on the inside corners of the seams with a thicker based (if I understand correctly there's different viscosities) WO much like silicone in a glass tank?

Nope, totally different process. WO solvent (#3, #4) soaks into the joints via "capilary action" and then dissolves the material so that it melts into one. Nothing like silicone on glass at all.

I could use an acrylic resin (WO #40, #42) and run beads along the insides of the bad seams, but that would be a pretty iffy fix at best. Guessets installed with GOOD WO #4 should make it plenty strong and leak free, but it will look even worse than a WO #16 repair, but be much stronger.

 

[Pat02026]

Good info, Thanks John.