Been searching off and on for plastic blades because of scratch sensitive glass in CCU.
Three recommendations leading with the best.
The Miniscraper firm manufactures 6" plastic blades which are rigid enough to spring concrete off windows. These blades fit into the Triumph and Ettore scraper handles.
The LilChizler is a 3" plastic blade usually used for scraping pots. It is rigid, inexpensive, small but respectable.
I do not recommend ScrapeRite - the other plastic blade manufacturer I found. I don’t know if the product is good but their customer service does not exist. I emailed them on multiple occasions over two years and they didn’t reply.
There are suppliers of generic plastic blades but these are not rigid.
I have to wonder how a plastic blade could diminish the chances of scratching glass if you’re using it on concrete. If anything it seems more likely to do the opposite. Concrete is harder than plastic, seems more likely fine particles of concrete could easily embed in the plastic blade itself than a metal blade, thus increasing the chances that you scratch the glass by removing the concrete. Not only that, but the remaining residue you then scrub off with wool is more likely to contain larger pieces that could then get embedded in the scrubber - what ever you use. No matter how soft your scrubber is, if it has glass scratching particulates in it it’ll scratch glass.
As such, I have to think a plastic blade with concrete is more likely to lead to scratches in glass myself. If fine particulates can scratch glass by riding along a metal blade, then surely a plastic blade can only increase the likelihood of that happening; and increase the likelihood of further damage when the remaining debris is removed.
For overspray that isn’t hard enough to scratch glass a plastic blade might be functional in removing the main particles but can’t see any real reason to use one myself. Tempered glass can be cleaned with oil flow or similar solvent. For light overspray Dirtex works good. Just plenty of ways to go than using a plastic blade imho. The risks seem to outweigh the potential benefits from my perspective. Just my two cents.
Concrete doesn’t in practice get stuck in the plastic itself. I’ve never seen that happen.
Concrete can damage the plastic and the noise sounds grim but it still doesn’t cause scratches. I’ve seen metal and plastic blades tested against concrete on the same glass. Plastic takes longer but does not scratch. Metal creates these characteristic line marks - sometimes difficult to see until you have direct sunlight. This is all on architectural or scratch sensitive glass.
What I’m saying is with the provision that you are swiping with a stroke that is going in one direction - lifting after a stroke and repeating. If you are just moving the blade up and down you can catch grit and you’re right that grit does scratch. This is true for both blade materials.
I accept the point that missing grit could lead to damage - but I have technique I use with the plastic blades that prevents that possibility - which is to -
Blade the glass. Replace blade if too corrupted.
Check with applicator and squeegee. Remaining grit stands out with soap suds.
If grit is all gone then apply red pad with cream abrasive or wool.
No matter how soft your scrubber is, if it has glass scratching particulates in it it’ll scratch glass.
Now - I’m not going to say that is completely wrong because we both agree it’s a bad scenario not to get into - but I have been surprised with red pad’s ability to absorb grit and still not scratch. I agree it is more likely. Red pad is for floor buffers - has larger pores than white and we don’t see swirly marks on floors every time a buffer catches some grit - they have some ability that steel wool wouldn’t have,
I suggest trying this yourself - I prefer physical removal to chemical but would like to experiment with liquid hammer on the outside since it’s not toxic. I can’t get it shipped to my country. Are any of the solvents you mentioned sure to not damage finishes or health? I’m more of a worry wart than most people.
Glass surfaces are indeed “alive” as Doctor Paul Duffer says. Many times it is the glass surface that is responsible for scratches and not the implement. Although a good diamond score tool that is used by glaziers will scratch glass every time. Marc Tanner “fixes” scratch sensitive glass by a multiple polishing technique. I know how to make any glass surface scratch sensitive and then make it scratch resistant. I am making the videos. This is the essence of the science of non-routine window cleaning. The IWCA Glass Committee has learned SO much over the last ten years.
