Engineers PLEASE help - acrylic stress

[robkob]

Has anybody ever seen this in a seam before? It's a translucent milky white stress mark in the seam that has been growing for about a week. The manufacturer is out of business so I can't call them. I talked to a local acrylic company, who does not build aquariums, and they said it might be something called acrylic stress and no big deal, or something majorly wrong.

I had it evaluated by a guy who works for the company that did the install, who previously worked for an acrylic tank manufacturer, and he said it is nothing to be worried about. Meanwhile this milky white crescent shape in the seam keeps growing.

The tank is 750 gallons and has been set up since July, and there are no metal halides on it.

How serious a problem is this? I am considering draining it tomorrow, which will be a major PITA since I will have to find temporary shelter for all my fish.

 

[Princley]

hm man i hope this don't happen but i have seen acrylic tanks bust a seam b4 and if that happend the whole seam can go where as galss tank just leaks.. i wish u luck man

 

[AquataHolic420]

wish u luck.. whats in there?

 

[RadleyMiller]

Wow, that is way beyond anything that I would know how to fix. The only thing I would do is cross my fingers then get out the Yellow Book and start calling people.

 

[robkob]

wish u luck.. whats in there?

3 emperor cichlids, 2 red belly pacus, 2 dats, 2 rc knives, 1 royal pleco, 1 sailfin pleco, 1 sa lung, 1 sil aro, 1 tsn, 1 ornate.

Draining in progress...

 

[Steve_89]

I can't help you unfortunatley, but I wish you all the best.

 

[Tongue33]

This computer i'm on sucks let me check when i get home May not be of much help but have a little experience here

 

[Dominuslive]

Sounds like the seam wasn't exactly clean when they applied the "glue" and the seam is seperating. Yes, drain it. Or it will drain itself. I'll talk to our acylic and corian guy tomorrow and see what he says. You may have to take the tank apart and reseam the whole thing. Joe will know the answer to that. But you may be able to buy the 2 part "glue" and just go over the whole seam and it will bond again. I am no expert on that though. I do know you will have to drain it though.

 

[Dominuslive]

This may be of some help.






There are several types of glue used with acrylic. The main type and most common are solvent adhesive. They are available thickened and water thin. The water thin is used in common fabrication. It uses capillary action to flow between the pieces of acrylic. The chemical is actually a solvent and breaks down the plastic surface, allowing the pieces to flow together. The solvent evaporates and you have a beautiful seam. We use methylene chloride, (MDC), as our solvent adhesive. We mix it with a small amount of another chemical that allows us to adjust for temperature. It is applied using an applicator bottle that has a needle tip. Edge preparation prior to glue application is of utmost importance. Your final seam will never be better than your beginning edge. We use a joiner to prep the edge for general assembly but a hand scraped finish used on our art quality work yields the best results.
The other glue is 2 part. Basically, 2 part uses a thick liquid material that is part acrylic and a catalyst to make the reaction that hardens it. It is much harder to use, messier and in my opinion does not give as long a lasting or strong seam on average. It is used most often in furniture manufacturing where seams are made using very thick material. Solvent adhesives are harder to use on thick acrylic. Acrylic often forms some gas as the solvent reacts. Usually it can escape to the side of the seam but at 3/4 to 1" and above, small bubbles may form.

For Polycarb you also want a solvent adhesive. (Lexan is a brand name), It has a tendency to absorb moisture. The moisture interferes with the gluing and heating process. It tends to make the seams turn white and will boil in the plastic if heated incorrectly. Fun stuff huh? We hate to fabricate polycarb. We do bend it with good results in 1/8" and 3/16". You have to be very careful at 1/4" and cross your fingers any thicker. Heat slow and flip the piece over often. It takes a long time to heat and cools in a couple seconds. It's easy to burn the surface before you get the center hot.

For solvent adhesives, I recommend Craftics Inc. They can ship them. We do not have a haz mat license. For polycarb you want to us weld-on #4. For acrylic, you can use weld-on #4 or #5 You will also need an applicator, smallest needle diameter, 16 gage or the water thin solvents. We think the 2 oz bottle is easiest to handle.

Craftics web site is http://www.craftics.com

For other fabrication information, try http://www.Cyro.com
They have fabrication manuals available and will send them to you or tell you where you can get them. If in Arizona, Curbel plastics in Phoenix has them.





I would say they ran a little light on the solvent in that area, and if the mark is growing it will split. Fortunately you only have to run the solvent on the edges for it to weld it back together.

 

[Dr Joe]

This may be of some help.






There are several types of glue used with acrylic. The main type and most common are solvent adhesive. They are available thickened and water thin. The water thin is used in common fabrication. It uses capillary action to flow between the pieces of acrylic. The chemical is actually a solvent and breaks down the plastic surface, allowing the pieces to flow together. The solvent evaporates and you have a beautiful seam. We use methylene chloride, (MDC), as our solvent adhesive. We mix it with a small amount of another chemical that allows us to adjust for temperature. It is applied using an applicator bottle that has a needle tip. Edge preparation prior to glue application is of utmost importance. Your final seam will never be better than your beginning edge. We use a joiner to prep the edge for general assembly but a hand scraped finish used on our art quality work yields the best results.
The other glue is 2 part. Basically, 2 part uses a thick liquid material that is part acrylic and a catalyst to make the reaction that hardens it. It is much harder to use, messier and in my opinion does not give as long a lasting or strong seam on average. It is used most often in furniture manufacturing where seams are made using very thick material. Solvent adhesives are harder to use on thick acrylic. Acrylic often forms some gas as the solvent reacts. Usually it can escape to the side of the seam but at 3/4 to 1" and above, small bubbles may form.

For Polycarb you also want a solvent adhesive. (Lexan is a brand name), It has a tendency to absorb moisture. The moisture interferes with the gluing and heating process. It tends to make the seams turn white and will boil in the plastic if heated incorrectly. Fun stuff huh? We hate to fabricate polycarb. We do bend it with good results in 1/8" and 3/16". You have to be very careful at 1/4" and cross your fingers any thicker. Heat slow and flip the piece over often. It takes a long time to heat and cools in a couple seconds. It's easy to burn the surface before you get the center hot.

For solvent adhesives, I recommend Craftics Inc. They can ship them. We do not have a haz mat license. For polycarb you want to us weld-on #4. For acrylic, you can use weld-on #4 or #5 You will also need an applicator, smallest needle diameter, 16 gage or the water thin solvents. We think the 2 oz bottle is easiest to handle.

Craftics web site is http://www.craftics.com

For other fabrication information, try http://www.Cyro.com
They have fabrication manuals available and will send them to you or tell you where you can get them. If in Arizona, Curbel plastics in Phoenix has them.





I would say they ran a little light on the solvent in that area, and if the mark is growing it will split. Fortunately you only have to run the solvent on the edges for it to weld it back together.

Wow...Excellent post.

If there isn't an edge opening available would you suggest drilling a pin hole into the center of the bubble/air pocket and injecting solvent into it? I have used this tactic before but never on a tank with this much stress.

This should be a sticky! Sre you listening Mods?

Dr Joe

.