I have tried unsuccesfully to fix some cracked plastic wall and trims around doors, using 1. fiber glass putty. 2. epoxy composite but both have failed, and cracks came back ! Anyone out there have an idea what kind of stuff would fix those cracks for good ???
how to fix for good, cracked plastic walls on old rv's
- Thread starter frenchie
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B and C
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A pic would help a lot.
Maybe use Dicor smoothed over?
Maybe use Dicor smoothed over?
If you are talking about the trims on the interior then fiberglass repair kits won't work on it.
Repairing plastic auto interior trim panels can be done with JB Weld along with some other products such as primer and paint that is made to stick to that type of plastic. Here is an article from the Napa auto parts store on how to make then look nice again. http://knowhow.napaonline.com/busted-fix-broken-plastic-trim/
Repairing plastic auto interior trim panels can be done with JB Weld along with some other products such as primer and paint that is made to stick to that type of plastic. Here is an article from the Napa auto parts store on how to make then look nice again. http://knowhow.napaonline.com/busted-fix-broken-plastic-trim/
highdesertranger
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if it's old, brittle, dry and has yellowed I don't think anything will work. it's done. highdesertranger
yes it's kinda yellowed, so perhaps your answer is the correct one... I really thought fiber glass auto body putty would have fix it for good, but it wasn't the case... worst case senario, I can put sealant just to make sure water won't get in... it not the best as far as ''look'' is concern !highdesertranger said:
I think this is going to be your best bet for a repair scheme. Try using some WELD-ON 2354 on those cracks. It is a watery thin adhesive that "welds" quite a few plastics back together. If there is a plastic supply house near where you are staying they might stock it. Otherwise it will likely have to be shipped to you by ground transportation which of course does not happen overnight.
For thin cracks I prefer to apply it with a very small artist brush letting it wick off the brush into the crack. You can't just pour it on the surface, that does not work. Do not touch the surface where you have applied it until it has dried or you will smear this adhesive over the plastic. This adhesives softens the plastic and then when it has cured the location of the crack will have both sides bonded back into one.
Of course old plastic will continue to age from UV. To stop that you need to paint it so the UV does not reach the plastic. Hang onto the can of the adhesive, old plastic is still going to be brittle so new cracks can happen if it takes an impact or other stress applied against it such as leaning on it.
No doubt you have used something similar which softens the plastics and forms them into one piece when working with plastic plumbing pipes. But you have to use the right formula of this class of adhesives for specific types of plastic.
For thin cracks I prefer to apply it with a very small artist brush letting it wick off the brush into the crack. You can't just pour it on the surface, that does not work. Do not touch the surface where you have applied it until it has dried or you will smear this adhesive over the plastic. This adhesives softens the plastic and then when it has cured the location of the crack will have both sides bonded back into one.
Of course old plastic will continue to age from UV. To stop that you need to paint it so the UV does not reach the plastic. Hang onto the can of the adhesive, old plastic is still going to be brittle so new cracks can happen if it takes an impact or other stress applied against it such as leaning on it.
No doubt you have used something similar which softens the plastics and forms them into one piece when working with plastic plumbing pipes. But you have to use the right formula of this class of adhesives for specific types of plastic.
Thank you maki2, your comments sound very logical to me... I will be looking for this weld on 2354 but it won't be until spring (for us in eastern Canada, this mean not before may) One detail I forgot to mentioned, although you probably guested... these cracks are on vertical surfaces, mean if your weld on stuff leaks, then it will be hard to avoid leakings !
Like I said you take a very tiny artist brush with a fine point. Dip it into the can then let it wick off the brush into the crack. That is how I do it on vertical surfaces.frenchie said:
I had a cracked, curved acrylic window on the front of my fiberglass Sunrader RV. I could not afford to have a replacement window custom made. So instead I used a different forumula ofWeld-on, an acrylic cement, that was also watery thin to seal up all those cracks. One of them was even a small hit by a rock with a bit of star shaped cracks radiating out. It sealed that up as well. I am also a model maker and sometimes working with styrene plastic parts and use yet another Weld-On, watery thin formula to bond those parts together. Once again wicking the glue off the tip of the tiny artist brush has given me the best control over the flow and the placement of the adhesive.
If you do have some cracks and they seem to be running out larger at the ends get your drill motor and drill a very tiny hole at those end. That will stop the crack from spreading just make sure it is a tiny drill bit as you want the Weld-On to be able to fill it. It is somewhat possible to fill a slightly larger hole if you have a scrap of matching plastic, sand it into a powder than mix it with a little of the adhesive and then quickly and carefully push it into that very small void. After it is dry you can smooth it out with sandpaper. Once you paint you won't see it.
On some types of RV waste tanks taking the sanded plastic and mixing it with the bonding cement is a common mending technique. There are many ways of mending, repairing and replacing things with substitute materials that come up in RVs. No one knows all of them.
Maybe you meant if you missed a spot it will leak through that? No problem just touch up the spot with the Weld-On and it will melt those plastic edges of the crack together to fill it in. It is not like applying caulk. You will be actually melting the plastic with the solvent and it can be done in the same spot more than once if needed. It won't look pretty but paint takes care of that.frenchie said:
thanks again maki2 for your instructive comments. Like I said, it won't e until spring, but till then, I'll have plenty of time to order the weld on product. Will try to take pictures ''before & after'' for members to see !
highest_vision
Well-known member
It sounds like your plastic isn't a good candidate for this, but for future readers, there is a tool called a plastic welder.
https://www.northerntool.com/shop/tools/product_200626118_200626118
They are spendy and have a learning curve, but work very well once mastered! Maybe they can be rented from parts stores. You have to be able to ID the plastic you are working with, just like you would need to know what metal you are welding.
https://www.northerntool.com/shop/tools/product_200626118_200626118
They are spendy and have a learning curve, but work very well once mastered! Maybe they can be rented from parts stores. You have to be able to ID the plastic you are working with, just like you would need to know what metal you are welding.
How can I tell which kind of plastic I have ??? Already heard that not all kind of plastics can be work the same way. I will make a few test like triyng to have some plastic dust soak in acetone, if so, i then can ''weld'' it with acetone ( just my toughts)
It might be Styrene plastic which is a high impact plastic. It does yellow a lot from UV exposure. Or it might be ABS which is also a high impact plastic that will yellow. Both of those plastics get used for exterior and interior trim pieces on RVs and automobiles. The Weld-on 2354 I recommended to you will work on both of those types of plastics. Here is an information sheet on it from the Company Tap Plastics with all the information you need to know about it. Fortunately for me Tap Plastics has a store near to where I am, I get a number of supplies from them for various projects I have worked on over the years so I can walk into the store or several other nearby plastics suppliers in my industrial area and buy cans of Weld-On formulas off the shelf.
https://www.tapplastics.com/uploads/pdf/PB-IPS2354.pdf
I would not recommend an adhesive to you I did not think it had an very good chance of solving the issue.
https://www.tapplastics.com/uploads/pdf/PB-IPS2354.pdf
I would not recommend an adhesive to you I did not think it had an very good chance of solving the issue.
highest_vision
Well-known member
I think the product maki2 is recommending is the best in your situation. The plastic welders are great when you have plastic in good condition, but it sounds like your plastic is perhaps a little weather worn? It would then be like trying to weld rusty metal - not a good end result for the effort invested.
Can you share pictures of the pieces?
Can you share pictures of the pieces?
The unfortunate situation is that for the much older RVs there is no source for replacement exterior trim parts other than possibly in an RV junk yard or finding someone somewhere on craigslist who is scrapping one out.
The only other workaround is to use the old piece as a mother mold and layup thin fiberglass cloth and resin over it. Lots of videos on how to layup fiberglass over a shape. I would use the thin E Glass Cloth and epoxy resin for something like that for what is just a trim panel rather than being a structural, weight bearing, component.
The only other workaround is to use the old piece as a mother mold and layup thin fiberglass cloth and resin over it. Lots of videos on how to layup fiberglass over a shape. I would use the thin E Glass Cloth and epoxy resin for something like that for what is just a trim panel rather than being a structural, weight bearing, component.
highest_vision
Well-known member
Eye of the beholder. it will be a better bond with decent plastic, and then give a structure to work with. Epoxies and chemical bonds cannot compare, but are better when the plastic isn't in great condition as noted. Either way, once pieces are reconnected, work will need to be done to hide what was once two, but is now onemaki2 said:
nature lover
Well-known member
Personally I am a disciple of Red Green. If Duck Tape isn't strong enough try reinforcing it with a flattened beer can with the duck tape.
