Plastic Crack Repair

[lovemy51]

Very nice! What epoxy did you use? I have a similar problem -- a vertical crack at the barrel thread of a Conway Stewart 28. The section was secured (by a professional restorer) with shellac, so the section is not moving; therefore, the crack might not get worse. And I don't want to remove the section to do a solvent weld from the inside of the barrel. But I'd like to fill the crack nonetheless. I paid only $40 for the pen so I am not keen on spending any more on it.

my problem, exactly -except i had paid $30 for the pen/pencil set.

 

the epoxy is the Devcon: http://www.amazon.com/Devcon-62345-Strength-Plastic-Filled/dp/B000KE0T3O

 

it dries black, reason why i got it. i'm sure there are others that dry clear.

 

regards,

 

edited to add: got mine at Tap Plastics... in case you have one of those stores close by -i know they are on the US west coast.

Edited October 21, 2011 by lovemy51

[Gerry]

Just my $0.02 worth.

 

Anothr possible filler technique to employ is an acrylic repair material such as that used for repairing acrylic fingernails - hey it's all acrylic, right?

 

The product I use is a KISS product, found in drugstores with extensive makeup sections.

 

It consists of a clear acrylic powder, a solvent and a applicator brush. One dips the brush into the solvent, then in the powder, and then apply's it to the area to be repaired. When the solvent dissolves the powder and the neighboring plastic, it joins permanently. The repair can be sanded and polished when completely dried.

 

Works like a champ

 

Regards

 

Gerry

[lovemy51]

Just my $0.02 worth.

 

Anothr possible filler technique to employ is an acrylic repair material such as that used for repairing acrylic fingernails - hey it's all acrylic, right?

 

The product I use is a KISS product, found in drugstores with extensive makeup sections.

 

It consists of a clear acrylic powder, a solvent and a applicator brush. One dips the brush into the solvent, then in the powder, and then apply's it to the area to be repaired. When the solvent dissolves the powder and the neighboring plastic, it joins permanently. The repair can be sanded and polished when completely dried.

 

Works like a champ

 

Regards

 

Gerry

thank u, Gerry. if i'm understanding this correctly, i can even use this to smooth out the dent/gouge seen in the pic. am i correct?

 

PS. today i went as far as to damp the barrel with a little bit of acetone to see if i can fix that dent, but it wasn't strong enough solvent to do the job.

 

no, no, nothing happen to the pen!!! it still looks the same, after some polish.

[OcalaFlGuy]

Very nice! What epoxy did you use? I have a similar problem -- a vertical crack at the barrel thread of a Conway Stewart 28. The section was secured (by a professional restorer) with shellac, so the section is not moving; therefore, the crack might not get worse. And I don't want to remove the section to do a solvent weld from the inside of the barrel. But I'd like to fill the crack nonetheless. I paid only $40 for the pen so I am not keen on spending any more on it.

 

Tim, if your pen were mine, I Would Not attempt the same epoxy filler method on it that LM51 tried on his Waterman. There are Critical differences between the two mainly that yours involves damage in both a threaded area and that threaded area is also a "stressed" point where the barrel end on the Waterman isn't. Unless you are skilled and have special thread cutting dies your same type repair is likely to be both unsightly and may leave the threading such that the cap no longer screws on or securely screws on.

 

No disrespect meant to you but if all the restorer who did your pen was to shellac the section in and not FIRST solvent weld the crack closed, his repair WASN'T very professional. A Pro may have shellaced the section in but *only after* first welding the crack closed and possible inserting a sleeve inside the barrel end for added structural strength to the repair. IF you attempt to separate your barrel section now (if all that was used was JUST shellac) you are likely to either make the crack worse or break it all the way through.

 

Unfortunately, the safest thing for you to do I think is to continue to use the pen as it is now. Sorry.

 

Bruce in Ocala, FL-that solvent welding class is a toughie, trust me

[OcalaFlGuy]

 

thank u, Gerry. if i'm understanding this correctly, i can even use this to smooth out the dent/gouge seen in the pic. am i correct?

 

PS. today i went as far as to damp the barrel with a little bit of acetone to see if i can fix that dent, but it wasn't strong enough solvent to do the job.

 

no, no, nothing happen to the pen!!! it still looks the same, after some polish.

 

LM51, IMO, (and my advice is easily worth 4x it's cost ) I think your progress so far speaks favorably enough for itself.

 

I'd give the epoxy/sanding/polishing another go myself.

 

Bruce in Ocala, FL

[Gerry]

Just my $0.02 worth.

 

Anothr possible filler technique to employ is an acrylic repair material such as that used for repairing acrylic fingernails - hey it's all acrylic, right?

 

The product I use is a KISS product, found in drugstores with extensive makeup sections.

 

It consists of a clear acrylic powder, a solvent and a applicator brush. One dips the brush into the solvent, then in the powder, and then apply's it to the area to be repaired. When the solvent dissolves the powder and the neighboring plastic, it joins permanently. The repair can be sanded and polished when completely dried.

 

Works like a champ

 

Regards

 

Gerry

thank u, Gerry. if i'm understanding this correctly, i can even use this to smooth out the dent/gouge seen in the pic. am i correct?

 

PS. today i went as far as to damp the barrel with a little bit of acetone to see if i can fix that dent, but it wasn't strong enough solvent to do the job.

 

no, no, nothing happen to the pen!!! it still looks the same, after some polish.

 

I'm afraid I'm going to have to modify my advice a little bit. I was actually thinking that the request was to smooth out the dent/gouge, and primarily that's what I addressed. The product I mentioned will deal with that very well.

 

What I need to correct is that this advice might have been thought as a crack repair technique I was recommending. It was not.

 

There are a lot of considerations that need to be addressed in crack repair, and they aren't usually trivial. A filler is usually inappropriate. I finally awoke to the fact that you are talking about a cracked blind cap so it's likely a structural defect, ie you need sufficient strength to resist the forces acting on it. With the part involving threads, there are a couple of additional points 1) the wall thickness is less than the rest of the barrel, and 2) the threads act as stress concentrators, weakening the area even further.

 

Just to give you an idea of the forces involved - consider the crack area: perhaps 1.5" x 1/16", or 0.09375 square inches. That's not much area for a glue to hold, especially if you twist the cap on firmly, or consider the loss due to the threads (area and stress concentration). For a 2,000 psi glue - only 187 pound strength can be expected. While solvent welding is tedious, as well as requiring a lot of patience (and the right solvent) it is the only repair that offers the prospect of almost the same strength as the undamaged cap would have had.

 

Proper repair after other methods have been tried is also pretty difficult, since it is very difficult to remove the foreign material so that the solvent can act to dissolve the cap material.

 

Finally, there's the question of thread restoration after the welding. If the cap diameter has been somewhat reduced by the solvent, and if in rejoining the cracked parts, one reduces the cap diameter even a little, the forces on the cap when it's screwed back on are going to be quite a lot higher than they were before. That, and the fact that the threads at the joint will be distorted, speak to the need to have some sort of re-threading capability so they can be brought back to the original specs.

 

I am not trying to overstate the issue, but I am trying to pass on enough information so that people reading this don't think it's trivial, or even simple to restore barrel or cap cracks when they involve threads.

 

If the pen is valuable, I would recommend that you consider employing one of the professional restorers that frequent the board. Ron has already offered a little advice in the thread, and I am in awe of his knowledge and ability regarding plastic restoration myself - but there are a few others who could also handle the job.

 

As for your question regarding filling a gouge - I stand by my advice. It's a pretty good repair, and easily sanded / buffed to become invisible. The solvent included in the kit may also work, as would Tenax, which Ron mentioned.

 

Sorry for the length of the post, it's simply a complex question which needs a little explanation.

 

Regards,

 

Gerry

 

PS: Not sure about the acetone, but multiple 'dampenings' are usually required for a solvent weld. If there was absolutely no visible effect from the acetone application it probably is the wrong solvent for that plastic. Try others (MEK, Tenax, etc.) - with appropriate consideration for safety.

 

 

[ttakacs]

Very nice! What epoxy did you use? I have a similar problem -- a vertical crack at the barrel thread of a Conway Stewart 28. The section was secured (by a professional restorer) with shellac, so the section is not moving; therefore, the crack might not get worse. And I don't want to remove the section to do a solvent weld from the inside of the barrel. But I'd like to fill the crack nonetheless. I paid only $40 for the pen so I am not keen on spending any more on it.

 

Tim, if your pen were mine, I Would Not attempt the same epoxy filler method on it that LM51 tried on his Waterman. There are Critical differences between the two mainly that yours involves damage in both a threaded area and that threaded area is also a "stressed" point where the barrel end on the Waterman isn't. Unless you are skilled and have special thread cutting dies your same type repair is likely to be both unsightly and may leave the threading such that the cap no longer screws on or securely screws on.

 

No disrespect meant to you but if all the restorer who did your pen was to shellac the section in and not FIRST solvent weld the crack closed, his repair WASN'T very professional. A Pro may have shellaced the section in but *only after* first welding the crack closed and possible inserting a sleeve inside the barrel end for added structural strength to the repair. IF you attempt to separate your barrel section now (if all that was used was JUST shellac) you are likely to either make the crack worse or break it all the way through.

 

Unfortunately, the safest thing for you to do I think is to continue to use the pen as it is now. Sorry.

 

Bruce in Ocala, FL-that solvent welding class is a toughie, trust me

 

Hi Bruce,

 

I bought the pen here knowing that the crack had been solvent-welded. Because the lever failed, I sent the pen out for repair. The crack probably reopened when the restorer removed the section. I don't blame the restorer -- he didn't cause the crack and wasn't asked to repair it.

 

You seem to have surmised the intent of my question. I don't want to effect an amateur repair that makes things worse. Thanks for the words of warning: I believe I am going to leave the pen the way it is.

[OcalaFlGuy]

I always like to say Tim, the best painful lessons in life are those that you can watch or hear about Someone Else Make and be able to learn from without feeling the pain yourself...

 

Bruce in Ocala, FL-originally said about up close and personal relationships with moving asphalt

[lovemy51]

Just my $0.02 worth.

 

Anothr possible filler technique to employ is an acrylic repair material such as that used for repairing acrylic fingernails - hey it's all acrylic, right?

 

The product I use is a KISS product, found in drugstores with extensive makeup sections.

 

It consists of a clear acrylic powder, a solvent and a applicator brush. One dips the brush into the solvent, then in the powder, and then apply's it to the area to be repaired. When the solvent dissolves the powder and the neighboring plastic, it joins permanently. The repair can be sanded and polished when completely dried.

 

Works like a champ

 

Regards

 

Gerry

thank u, Gerry. if i'm understanding this correctly, i can even use this to smooth out the dent/gouge seen in the pic. am i correct?

 

PS. today i went as far as to damp the barrel with a little bit of acetone to see if i can fix that dent, but it wasn't strong enough solvent to do the job.

 

no, no, nothing happen to the pen!!! it still looks the same, after some polish.

 

I'm afraid I'm going to have to modify my advice a little bit. I was actually thinking that the request was to smooth out the dent/gouge, and primarily that's what I addressed. The product I mentioned will deal with that very well.

 

What I need to correct is that this advice might have been thought as a crack repair technique I was recommending. It was not.

 

There are a lot of considerations that need to be addressed in crack repair, and they aren't usually trivial. A filler is usually inappropriate. I finally awoke to the fact that you are talking about a cracked blind cap so it's likely a structural defect, ie you need sufficient strength to resist the forces acting on it. With the part involving threads, there are a couple of additional points 1) the wall thickness is less than the rest of the barrel, and 2) the threads act as stress concentrators, weakening the area even further.

 

Just to give you an idea of the forces involved - consider the crack area: perhaps 1.5" x 1/16", or 0.09375 square inches. That's not much area for a glue to hold, especially if you twist the cap on firmly, or consider the loss due to the threads (area and stress concentration). For a 2,000 psi glue - only 187 pound strength can be expected. While solvent welding is tedious, as well as requiring a lot of patience (and the right solvent) it is the only repair that offers the prospect of almost the same strength as the undamaged cap would have had.

 

Proper repair after other methods have been tried is also pretty difficult, since it is very difficult to remove the foreign material so that the solvent can act to dissolve the cap material.

 

Finally, there's the question of thread restoration after the welding. If the cap diameter has been somewhat reduced by the solvent, and if in rejoining the cracked parts, one reduces the cap diameter even a little, the forces on the cap when it's screwed back on are going to be quite a lot higher than they were before. That, and the fact that the threads at the joint will be distorted, speak to the need to have some sort of re-threading capability so they can be brought back to the original specs.

 

I am not trying to overstate the issue, but I am trying to pass on enough information so that people reading this don't think it's trivial, or even simple to restore barrel or cap cracks when they involve threads.

 

If the pen is valuable, I would recommend that you consider employing one of the professional restorers that frequent the board. Ron has already offered a little advice in the thread, and I am in awe of his knowledge and ability regarding plastic restoration myself - but there are a few others who could also handle the job.

 

As for your question regarding filling a gouge - I stand by my advice. It's a pretty good repair, and easily sanded / buffed to become invisible. The solvent included in the kit may also work, as would Tenax, which Ron mentioned.

 

Sorry for the length of the post, it's simply a complex question which needs a little explanation.

 

Regards,

 

Gerry

 

PS: Not sure about the acetone, but multiple 'dampenings' are usually required for a solvent weld. If there was absolutely no visible effect from the acetone application it probably is the wrong solvent for that plastic. Try others (MEK, Tenax, etc.) - with appropriate consideration for safety.

 

 

i got the point and i understood it that way: the acrylic was just to smooth out the dent. done!! it worked. all smooth and looks great. i can still see a very thin line underneath the acrylic coat, but it's so minimal, it bothers me none.

 

thx all of you for all the helpful info

[lovemy51]

where is Waldo?

 

http://i338.photobucket.com/albums/n419/peterpaul_rguez/PA240003.jpg

 

that horizontal white line you see is the gouge -now looks like a scratch. the crack is 100% gone!!!

[OcalaFlGuy]

You're almost done. Now make the scratch go away.

 

 

(You've come this far. Finish it. )

 

Bruce in Ocala, FL

[lovemy51]

You're almost done. Now make the scratch go away.

 

 

(You've come this far. Finish it. )

 

Bruce in Ocala, FL

can't. i made a mistake that i can't undo. the acrylic coat over the gouge is what made it reflect like a scratch . maybe if i have touched over the gouge with a permanent marker or something before applying the coat it wouldn't be as prominent.

Edited October 25, 2011 by lovemy51