Putty for acrylic

[Emmalina]

I am so bored buying 295 or whatever to seal a window. You always have 70% left in the tube and after a time its very hard to get out. I was thinking back to my misspent childhood when if we broke a window we had to go to the glazzers and get 1/2lb of putty and a piece of glass and fix it before the parents got home. I have acrylic windows in ss frames so I thought what the hell I will buy some linssed oil putty and give it a go. Easy to use and clean up and CHEAP also contains the oil that should preserve the stainless. Have done one will let you know how I get on

[AKA-None]

Wrong sealant for a boat window as it will not last long

[Emmalina]

Originally Posted by AKA-None

Wrong sealant for a boat window as it will not last long

On what basis ? Once it hardens enough to be painted !

[john61ct]

The whole point of sealant is to never really harden.

Marine conditions require a lot more than S&B buildings on land.

[Emmalina]

Originally Posted by john61ct

The whole point of sealant is to never really harden.

Marine conditions require a lot more than S&B buildings on land.

Do you know how flax oil works ?
Every poymer based sealant cures I know as when you remove them they are solid !

[Matt Johnson]

You're looking for the Joint Movement Capability percentage. Dow 795 is plus/minus 50% and works well with the expansion and contraction of acrylic in the sun.

Edit: Just looked up Linseed oil based Glazing putty and they have a joint movement capability of 2-5%. (this is from the Handbook of Sealant Technology)

Matt

[mikereed100]

+1 on the Dow 795, although you will not find it in Thailand. Acrylic can expand and contract quite a bit, especially if it is tinted. Keep in mind that 50% mobility in a 1/4" bead is only 1/8". 2-5% is basically nil.

[atoll]

don't use it to seal your skin fittings

[Emmalina]

Thanks all will wait and see. Anybody know the expansion rate of acrylic ? Sika 295 UV is bloody useless

[RaymondR]

I seem to recall that window putty is a mixture of boiled linseed oil and a filler such as talc. It tends to harden and lose it's flexibility fairly quickly. Boat windows and fittings need to be sealed with something which will retain it's flexibility. On my steel boat I started using rubber gaskets and mastics because of the difficulty of retaining a consistent thickness of sealant with the stuff out of a tube.

[john61ct]

Top quality butyl tape

[hellosailor]

"the expansion rate of acrylic ?" Will vary with the specific product. But with plexiglass, you are looking at vaguely 1/4" per linear foot as it goes through ambient temperatures where you're not cooking eggs or freeze distilling vodka.

Every maker can give you specifics. Every plastics dealer who is more than a "clerk" will also have access to that data.

[AKA-None]

Originally Posted by john61ct

Top quality butyl tape

This ...

[er9]

Originally Posted by Emmalina

Thanks all will wait and see. Anybody know the expansion rate of acrylic ? Sika 295 UV is bloody useless

2 - 4%

when we thermal form it in ovens we add 4% to overall size before we form it. it shrinks on average 4%. its not an exact science though there are so many variables.

for windows we generally undersize them 2 - 4% depending on how much sun they will get.

ive seen acrylic that was cut exact size destroy thick metal framing when it expanded from excessive heat.

[Emmalina]

Originally Posted by er9

2 - 4%

when we thermal form it in ovens we add 4% to overall size before we form it. it shrinks on average 4%. its not an exact science though there are so many variables.

for windows we generally undersize them 2 - 4% depending on how much sun they will get.

ive seen acrylic that was cut exact size destroy thick metal framing when it expanded from excessive heat.

Thanks for that I just looked into getting some 795 but the shipping cost is 3 times the price of the product ! Always seems to be like that from the states