Glueing problems

[rdhamr]

Hi,i hope someone can help me here! I back into the model building hobby and have been useing Mercury Adhesives M1000F and M1000G along with the Mercury Adhesives Accelerator MH16 and its happend twice now.I will be gluing a Big part like two wings and after about 8 mins after gluing,the plastic starts to crack and eventually will crack bad enough that pieces of plastic (dime size) will break off.Is this the glue or accelerator doing this? What is a good glue to use when joining two big pieces? Thanx for any info

Ken

[caudleryan]

Testors liquid cement

Tamiya extra thin cement

Ambroid Pro Weld

Tenax 7R

All of these are good glues for plastic.

RYAN.

[Miccara]

I use Tamiya extra thin cement for 95% of glueing.

[frankv74]

You want glue that will weld the plastice. You don't want to dry it like you aer with that glue you r using

[rdhamr]

Thanx everyone for helping me out,i was told that the Mercury glues were the way to go but thats definately not the case!

[gaz262]

Thanx everyone for helping me out,i was told that the Mercury glues were the way to go but thats definately not the case!

I use something called Plastic Weld but I'm in the UK and not sure how available this stuff is outside of England.....

Some folks actually used something called Mek over here - it's quite dodgy stuff and evaporates pretty quickly but welds the plastic pronto!

There used to be a product called Mek-Pak but I think that was withdrawn on H&S grounds, you need a plastic solvent for polystyrene rather than a cyanoacrylate (super or crazy glue) - it melts each edge of the part and basically welds them togather.

When I use Plastic Weld I find it best to hold the two parts together and let the glue flow into the joint using capilliary action - i.e. Use a small brush to apply the glue along the seam.

Good luck man!

Gaz

[Edgar]

It's quite possible that it was your accelerator; some are totally incompatible with plastic, in fact, somewhere down in the tiny letters (which you can only read with a magnifying glass) you might well find a warning not to use it on plastics.

Solvent glues are, in fact, easier to use, since you can hold the parts together, and then apply the glue, allowing it to run along the join by capillary action. Many (including Plasticweld) are dichloromethane, which needs careful handling, since it can have side effects (when I was younger, I would get blisters, inside my nose, after using it.)

Mek-Pak, originally, was methyl-ethyl-ketone, but the formula was rapidly changed, when scare-stories surfaced about its alleged toxicity/carcinogenic properties. These have been proved to be false, but the product has never reverted to its original formula. It's possible to buy MEK over the counter, at a plumber's outlet, since it's used as a cleaning agent for plastic pipes, before they're welded together with a DCM mixture. MEK labels have "flammable" and "harmful" on them, which is a long way from the "toxic" legend on DCM labels.

Edgar

[Slartibartfast]

From an MEK MSDS dated 2009

Inhalation:

Causes irritation to the nose and throat. Concentrations above the TLV may cause headache, dizziness, nausea, shortness of breath, and vomiting. Higher concentrations may cause central nervous system depression and unconsciousness.

Ingestion:

May produce abdominal pain, nausea. Aspiration into lungs can produce severe lung damage and is a medical emergency. Other symptoms expected to parallel inhalation.

Skin Contact:

Causes irritation to skin. Symptoms include redness, itching, and pain. May be absorbed through the skin with possible systemic effects.

Eye Contact:

Vapors are irritating to the eyes. Splashes can produce painful irritation and eye damage.

Chronic Exposure:

Prolonged skin contact may defat the skin and produce dermatitis. Chronic exposure may cause central nervous system effects.

Toxicological Data:

Oral rat LD50: 2737 mg/kg; inhalation rat LC50: 23,500 mg/m3/8-hr; skin rabbit LD50: 6480 mg/kg; investigated as a mutagen, reproductive effector.

Reproductive Toxicity:

Has shown teratogenic effects in laboratory animals.

The last two show long-term effects. In this case, none are indicated though it was investigated as a cancer agent. Apparently nothing conclusive. MEK does have effects on gametes, though. Make all your children before using MEK.

[Edgar]

Bit late for that; I became a father in 1990, 20 years after I started using it. Might be because I only use a small brushload, at a time, and don't bath in it, of course.

Edgar

[Hawkeye's Hobbies]

The Mercury glues you are using must be causing some crazing of the plastic causing it to become brittle and break.

Remember a glue is a membrane that holds to piece relative to each other. Eventually the glue breaks down and the bond is compromised. They typically cannot withstand a shearing action.

Solvents on the other hand melt the two surfaces forming a weld when pressure is applied to join the two together. Once common material that doesn't degrade any faster than the rest of the material for it is the same material.

You can suspend oil and water, but eventually they separate so it goes for glues and plastic too.

As with metal, the weld is actually has greater strength than the surrounding material.

I cover this in this article http://hawkeyes-squawkbox.com/2008/07/22/e...-perfect-seams/

[rdhamr]

The Mercury glues you are using must be causing some crazing of the plastic causing it to become brittle and break.

Remember a glue is a membrane that holds to piece relative to each other. Eventually the glue breaks down and the bond is compromised. They typically cannot withstand a shearing action.

Solvents on the other hand melt the two surfaces forming a weld when pressure is applied to join the two together. Once common material that doesn't degrade any faster than the rest of the material for it is the same material.

You can suspend oil and water, but eventually they separate so it goes for glues and plastic too.

As with metal, the weld is actually has greater strength than the surrounding material.

I cover this in this article http://hawkeyes-squawkbox.com/2008/07/22/e...-perfect-seams/

[rdhamr]

The Mercury glues you are using must be causing some crazing of the plastic causing it to become brittle and break.

Remember a glue is a membrane that holds to piece relative to each other. Eventually the glue breaks down and the bond is compromised. They typically cannot withstand a shearing action.

Solvents on the other hand melt the two surfaces forming a weld when pressure is applied to join the two together. Once common material that doesn't degrade any faster than the rest of the material for it is the same material.

You can suspend oil and water, but eventually they separate so it goes for glues and plastic too.

As with metal, the weld is actually has greater strength than the surrounding material.

I cover this in this article http://hawkeyes-squawkbox.com/2008/07/22/e...-perfect-seams/

Thank you again and to all the other members for the help,i think im gonna love this website!

[ventura_kelley]

Hi,i hope someone can help me here! I back into the model building hobby and have been useing Mercury Adhesives M1000F and M1000G along with the Mercury Adhesives Accelerator MH16 and its happend twice now.I will be gluing a Big part like two wings and after about 8 mins after gluing,the plastic starts to crack and eventually will crack bad enough that pieces of plastic (dime size) will break off.Is this the glue or accelerator doing this? What is a good glue to use when joining two big pieces? Thanx for any info

Ken

I use plastruct plastic weld and Zap CA's (Zap-A-Gap and Zap-CA).

Don't use pastruct plastic weld on trailing edges (wing, tail, whatever). It welds everything it touches together (except clear parts), but if it gets trapped between two thin parts in a confined space (like a trailing edge), it will melt through until it gets close enough to the atmosphere to evaporate.

I use the super glues (especially Zap-A-Gap - sand the mating surfaces first to give it something to bite into) on trailing edges.

I've never had much luck with Tenax 7R. It evaporates before I can put the parts together and apply clamps/tape.

Never used the Testors or Tamiya cements, though I've talked to guys who's every model is contest quality and they swear by Tamiya, so if results are your metric...